WorldWideScience

Sample records for group extensive quantum-chemical

  1. Accurate quantum chemical calculations

    Science.gov (United States)

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

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  2. A critical quantum chemical and experimental study of the potentiality of direct labeling of the CN group with [99mTc(CO)3]+ or [186/188Re(CO)3]+ in CN containing biomolecules

    International Nuclear Information System (INIS)

    Safi, Benasser; Mertens, John; Kersemans, Ken; Geerlings, Paul

    2008-01-01

    Introduction: It was determined recently that [ 99m Tc(OH 2 ) 2 (X - )(CO 3 ) 3 ] could strongly bind to the CN group, allowing direct labeling of CN in vitamin B 12 despite the presence of a benzimidazole group. The aim of this paper was to perform a critical study of this potentiality, coupling quantum chemical calculations to experimental evidence. Methods: Computational methods: Within the density functional theory calculations, the 6-31+G** basis set (C, H, O, N atoms) and the LANL2DZ basis set (Tc,Re) were used. Stability calculations of the [RCNM(CO) 3 ] + ) (M=Tc,Re) complexes were performed with the Gaussian 03 suite of programs, while for the evaluation of relative stability substitution reactions were used. Radiochemistry: Vitamin B 12 , 4-hydroxy-benzylcyanide and 4-methoxy-benzonitrile were labeled at 100 deg. C during 30 min. High-performance liquid chromatography analysis was performed using radioactive and UV detection. Results: Computational methods: The influence of different ligands on the stability yielded a sequence: imidazole>tBuCN>NH 3 ∼CH 3 CN>HCN (mimicking the best CoCN)>H 2 O. The transmetalation reaction indicates that all ligands prefer Re to Tc. The preference for the nitrogen atom of imidazole to the cyanide nitrogen atom for complex formation with [Tc(CO) 3 (H 2 O) 3 ] + is interpreted in terms of the hard and soft acid and base properties principle. Radiochemistry: 4-Hydroxy-benzylcyanide and 4-methoxy-benzonitrile did not show any labeling. An excess of acetonitrile did not inhibit the labeling of vitamin B 12 as expected if the CN group should be involved, indicating that the labeling occurs on a stronger complexing group present like benzimidazole. Conclusion: Both theory and experiments prove that [CN-Tc(CO) 3 (H 2 O) (2-x) L x ] + complexes are weak and that in vitamin B 12 most probably the benzimidazole group is involved

  3. molecular dynamics simulations and quantum chemical calculations

    African Journals Online (AJOL)

    ABSTRACT. The molecular dynamic (MD) simulation and quantum chemical calculations for the adsorption of [2-(2-Henicos-10- .... electronic properties of molecule clusters, surfaces and ... The local reactivity was analyzed by determining the.

  4. Quantum Chemical Approach to Estimating the Thermodynamics of Metabolic Reactions

    OpenAIRE

    Adrian Jinich; Dmitrij Rappoport; Ian Dunn; Benjamin Sanchez-Lengeling; Roberto Olivares-Amaya; Elad Noor; Arren Bar Even; Alán Aspuru-Guzik

    2014-01-01

    Thermodynamics plays an increasingly important role in modeling and engineering metabolism. We present the first nonempirical computational method for estimating standard Gibbs reaction energies of metabolic reactions based on quantum chemistry, which can help fill in the gaps in the existing thermodynamic data. When applied to a test set of reactions from core metabolism, the quantum chemical approach is comparable in accuracy to group contribution methods for isomerization and group transfe...

  5. Quantum chemical approach to estimating the thermodynamics of metabolic reactions.

    Science.gov (United States)

    Jinich, Adrian; Rappoport, Dmitrij; Dunn, Ian; Sanchez-Lengeling, Benjamin; Olivares-Amaya, Roberto; Noor, Elad; Even, Arren Bar; Aspuru-Guzik, Alán

    2014-11-12

    Thermodynamics plays an increasingly important role in modeling and engineering metabolism. We present the first nonempirical computational method for estimating standard Gibbs reaction energies of metabolic reactions based on quantum chemistry, which can help fill in the gaps in the existing thermodynamic data. When applied to a test set of reactions from core metabolism, the quantum chemical approach is comparable in accuracy to group contribution methods for isomerization and group transfer reactions and for reactions not including multiply charged anions. The errors in standard Gibbs reaction energy estimates are correlated with the charges of the participating molecules. The quantum chemical approach is amenable to systematic improvements and holds potential for providing thermodynamic data for all of metabolism.

  6. Remarks on the application of group extensions to quantization

    International Nuclear Information System (INIS)

    Mozrzymas, J.; Rzewuski, J.

    1976-01-01

    Quantization is described in the language of the theory of group extensions. Under the assumption of analyticity the most general form of factor of the extension is derived. A realization of the extended group in terms of functionals is described in the case of quantum field theory. The homomorphism of the extended group with the Weyl group of canonical commutation relations is demonstrated. (author)

  7. Central extensions of some Abelian finite gauge groups

    International Nuclear Information System (INIS)

    Combe, Ph.; Rodriguez, R.; Sirugue, M.; Sirugue-Collin, M.

    1981-01-01

    The authors describe central extensions of Abelian finite gauge groups on lattices which are permutation invariant. Moreover some remarks are made on the gauge models on lattice associated with these non-commutative central extensions. (Auth.)

  8. Quantum chemical studies of estrogenic compounds

    Science.gov (United States)

    Quantum chemical methods are potent tools to provide information on the chemical structure and electronic properties of organic molecules. Modern computational chemistry methods have provided a great deal of insight into the binding of estrogenic compounds to estrogenic receptors (ER), an important ...

  9. Definable Group Extensions and o-Minimal Group Cohomology via Spectral Sequences

    OpenAIRE

    BARRIGA, ELIANA

    2013-01-01

    We provide the theoretical foundation for the Lyndon-Hochschild-Serre spectral sequence as a tool to study the group cohomology and with this the group extensions in the category of definable groups. We also present various results on definable modules and actions, definable extensions and group cohomology of definable groups. These have applications to the study of non-definably compact groups definable in o-minimal theories (see [1]). Se presenta el fundamento teórico para las sucesiones...

  10. Extension of the analytic nodal method to four energy groups

    International Nuclear Information System (INIS)

    Parsons, D.K.; Nigg, D.W.

    1985-01-01

    The Analytic Nodal Method is one of several recently-developed coarse mesh numerical methods for efficiently and accurately solving the multidimensional static and transient neutron diffusion equations. This summary describes a mathematically rigorous extension of the Analytic Nodal Method to the frequently more physically realistic four-group case. A few general theoretical considerations are discussed, followed by some calculated results for a typical steady-state two-dimensional PWR quarter core application. 8 refs

  11. The BWR owners' group planning guide for life extension

    International Nuclear Information System (INIS)

    Smith, S.K.; Lehnert, D.F.; Locke, R.K.

    1991-01-01

    Extending the operating life of a commercial nuclear power plant has been shown to be economically beneficial to both the utility and the electric customer. As such, many utilities are planning and implementing plant life extension (PLEX) programs. A document has been developed which provides guidance to utilities in formulating a PLEX program plant for one or more boiling water reactor (BWR) plants. The guide has been developed by the BWR Owners' Group Plant Life Extension Committee. The principal bases for this guide were the BWR Pilot and Lead Plant Programs. These programs were used as models to develop the 'base plan' described in this guide. By formulating their program plant utilizing the base plan, utilities will be able to maximize the use of existing evaluations and results. The utility planner will build upon the base plan by adding any tasks or features that are unique to their programs. (author)

  12. Quantum-chemical study of the geometric and electronic structure of the chromate anion CrO42- and a chromate group on the surface of finely divided silica by the CNDO/2 method

    International Nuclear Information System (INIS)

    Plyuto, I.V.; Shpak, A.P.; Plyuto, Yu.V.; Chuiko, A.A.

    1989-01-01

    A comparative study of the geometric and electronic structure of the chromate anion CrO 4 2- and a chromate group on the surface of finely divided silica (≡Si-O) 2 - CrO 2 , which was simulated by a CrO 9 Si 6 H 12 cluster, has been carried out by the SCF-MO-LCAO method in the all-valence-electron CNDO/2 approximation. The data obtained on the equilibrium geometry of the chromate group attest to the formation of a double bond between the Cr atom and each O atom (which is not bonded to Si). It has been shown that the support has a significant stabilizing in fluence on the energy of the MO's of the chromate group. The chromate group on an SiO 2 surface is characterized by partial delocalization of the frontier MO's among the skeletal bonds; however, the dominant contribution to the HOMO is made by the 2p AO of the oxygen atoms in the coordination shell of the Cr atom (∼70%), and the dominant contribution to the LUMO is made by the 3d AO of the chromium atom (∼50%). The positions and composition of the lowest unoccupied molecular orbitals point out the possibility of the display of electron-acceptor properties by a chromate group of an SiO 2 surface

  13. Individual and Group Extension Methods: Perspectives from Vi ...

    African Journals Online (AJOL)

    Participatory Rural Appraisals (PRAs) tools including semi-structured questionnaires were administrated to 90 randomly selected farmers who had received extension services from the project. In addition, twelve project extension workers were interviewed. Data were analysed using SPSS computer package and descriptive ...

  14. Quantum chemical calculations in the structural analysis of phloretin

    Science.gov (United States)

    Gómez-Zavaglia, Andrea

    2009-07-01

    In this work, a conformational search on the molecule of phloretin [2',4',6'-Trihydroxy-3-(4-hydroxyphenyl)-propiophenone] has been performed. The molecule of phloretin has eight dihedral angles, four of them taking part in the carbon backbone and the other four, related with the orientation of the hydroxyl groups. A systematic search involving a random variation of the dihedral angles has been used to generate input structures for the quantum chemical calculations. Calculations at the DFT(B3LYP)/6-311++G(d,p) level of theory permitted the identification of 58 local minima belonging to the C 1 symmetry point group. The molecular structures of the conformers have been analyzed using hierarchical cluster analysis. This method allowed us to group conformers according to their similarities, and thus, to correlate the conformers' stability with structural parameters. The dendrogram obtained from the hierarchical cluster analysis depicted two main clusters. Cluster I included all the conformers with relative energies lower than 25 kJ mol -1 and cluster II, the remaining conformers. The possibility of forming intramolecular hydrogen bonds resulted the main factor contributing for the stability. Accordingly, all conformers depicting intramolecular H-bonds belong to cluster I. These conformations are clearly favored when the carbon backbone is as planar as possible. The values of the νC dbnd O and νOH vibrational modes were compared among all the conformers of phloretin. The redshifts associated with intramolecular H-bonds were correlated with the H-bonds distances and energies.

  15. Quantum chemical investigation of mechanisms of silane oxidation

    DEFF Research Database (Denmark)

    Mader, Mary M.; Norrby, Per-Ola

    2001-01-01

    Several mechanisms for the peroxide oxidation of organosilanes to alcohols are compared by quantum chemical calculations, including solvation with the PCM method. Without doubt, the reaction proceeds via anionic, pentacoordinate silicate species, but a profound difference is found between in vacuo...

  16. Experimental and quantum chemical studies on corrosion inhibition ...

    Indian Academy of Sciences (India)

    Abstract. The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also ...

  17. Quantum chemical calculations of using density functional theory ...

    Indian Academy of Sciences (India)

    K RACKESH JAWAHER

    2018-02-15

    Feb 15, 2018 ... Quantum chemical calculations have been employed to study the molecular effects produced by. Cr2O3/SnO2 optimised structure. ... are exploited in solar cells [2], high-capacity lithium– storage [3], solid-state chemical ..... bond distance of metal–oxygen is positively (0.5 Е) deviated to oxygen–oxygen ...

  18. Experimental and quantum chemical studies on corrosion inhibition

    Indian Academy of Sciences (India)

    The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also used to ...

  19. Cartan determinants, LIE algebra extensions, and the exceptional group series

    International Nuclear Information System (INIS)

    Capps, R.H.

    1986-01-01

    In this note the author utilizes the determinant of the generalized Cartan matrix for candidate Dynkin systems for two purposes. The first is to provide an uncomplicated criterion for classifying candidate one-root extensions of diagrams for semisimple Lie algebras. The second is to help determine some important properties of related Lie algebras and their representations

  20. Recent Trends in Quantum Chemical Modeling of Enzymatic Reactions.

    Science.gov (United States)

    Himo, Fahmi

    2017-05-24

    The quantum chemical cluster approach is a powerful method for investigating enzymatic reactions. Over the past two decades, a large number of highly diverse systems have been studied and a great wealth of mechanistic insight has been developed using this technique. This Perspective reviews the current status of the methodology. The latest technical developments are highlighted, and challenges are discussed. Some recent applications are presented to illustrate the capabilities and progress of this approach, and likely future directions are outlined.

  1. Quantum chemical studies on the some inorganic corrosion inhibitors

    International Nuclear Information System (INIS)

    Sayin, Koray; Karakaş, Duran

    2013-01-01

    Highlights: •Some quantum chemical parameters are important to determine inhibition efficiency. •Quantum chemical calculations were performed on six inorganic inhibitors. •Five experimental reports were used to explain the theoretical results. •Atomic charges and %contributions were used to determine the atom at protonation process. •For inorganic inhibitors, the best method and basis set were investigated. -- Abstract: Some quantum chemical parameters were calculated by using Hartree–Fock (HF) approximation, Density Functional Theory (DFT/B3LYP) and Møller Plesset perturbation theory (MP3) methods at LANL2DZ, LANL2MB and SDD levels in gas phase and water for dichromate (Cr 2 O 7 2- ), chromate (CrO 4 2- ), tungstate (WO 4 2- ), molybdate (MoO 4 2- ), nitrite (NO 2 - ) and nitrate (NO 3 - ) which are used as inorganic corrosion inhibitors. All theoretical results and experimental inhibition efficiencies of inhibitors were subjected to correlation analyses. In a summary, MP3/SDD level in water was found as the best level. In this level, the inhibition efficiency ranking was found as CrO 4 2- >WO 4 2- >MoO 4 2- >Cr 2 O 7 2- >NO 2 - ≈NO 3 -

  2. Quantum Chemical: New name and focus for National Distillers

    Energy Technology Data Exchange (ETDEWEB)

    Reisch, M.S.

    1988-03-14

    This article explains why the National Distillers and Chemical Corporation has narrowed its focus on petrochemicals and energy. At one time the company had diversified into wine and spirits, insurance, metals, chemicals and energy. However, the company decided to reexamine where its commitments should be. It decided to stick with chemicals and energy because it could be a leader in these fields and not in its other interests. The article explains how the new company, Quantum Chemical, is doing and where it is headed in the future.

  3. From quantum chemical formation free energies to evaporation rates

    Directory of Open Access Journals (Sweden)

    I. K. Ortega

    2012-01-01

    Full Text Available Atmospheric new particle formation is an important source of atmospheric aerosols. Large efforts have been made during the past few years to identify which molecules are behind this phenomenon, but the actual birth mechanism of the particles is not yet well known. Quantum chemical calculations have proven to be a powerful tool to gain new insights into the very first steps of particle formation. In the present study we use formation free energies calculated by quantum chemical methods to estimate the evaporation rates of species from sulfuric acid clusters containing ammonia or dimethylamine. We have found that dimethylamine forms much more stable clusters with sulphuric acid than ammonia does. On the other hand, the existence of a very deep local minimum for clusters with two sulfuric acid molecules and two dimethylamine molecules hinders their growth to larger clusters. These results indicate that other compounds may be needed to make clusters grow to larger sizes (containing more than three sulfuric acid molecules.

  4. On the Galois cohomology of unipotent groups and extensions of non-perfect fields

    International Nuclear Information System (INIS)

    Nguyen Duy Tan; Nguyen Quoc Thang

    2006-12-01

    In this note we discuss, in the case of unipotent groups over non-perfect fields, an analog of Serre's conjectures for unipotent algebraic group schemes, which relates properties of Galois (or flat) cohomology of unipotent group schemes to finite extensions of non-perfect fields, and Russel's defining equations of one-dimensional unipotent groups. (author)

  5. A quantum chemical explanation of the antioxidant activity af flavonoids.

    NARCIS (Netherlands)

    van Acker, S.A.B.E.; de Groot, M.J.; van den Berg, D.J.; Tromp, M.N.J.L.; Donné-Op den Kelder, G.M.; van der Vijgh, W.J.F.; Bast, A.

    1996-01-01

    Flavonoids are a group of naturally occurring antioxidants, which over the past years have gained tremendous interest because of their possible therapeutic applicability. The mechanism of their antioxidant activity has been extensively studied over several decades. However, there is still much

  6. Tracking Maneuvering Group Target with Extension Predicted and Best Model Augmentation Method Adapted

    Directory of Open Access Journals (Sweden)

    Linhai Gan

    2017-01-01

    Full Text Available The random matrix (RM method is widely applied for group target tracking. The assumption that the group extension keeps invariant in conventional RM method is not yet valid, as the orientation of the group varies rapidly while it is maneuvering; thus, a new approach with group extension predicted is derived here. To match the group maneuvering, a best model augmentation (BMA method is introduced. The existing BMA method uses a fixed basic model set, which may lead to a poor performance when it could not ensure basic coverage of true motion modes. Here, a maneuvering group target tracking algorithm is proposed, where the group extension prediction and the BMA adaption are exploited. The performance of the proposed algorithm will be illustrated by simulation.

  7. Quantum-chemical consideration of extermal valent forms of actinides

    International Nuclear Information System (INIS)

    Ionova, G.V.; Pershina, V.G.; Spitsyn, V.I.

    1982-01-01

    Stability of valent forms of actinides that has not yet studied experimentally, is considered within the framework of quantum-chemical considerations. Oxidizing potentials E 0 for actinide elements are determined theoretically. A dependence of the definite valent state stability on relativistic effect is shown. A conclusion is made that oxidizing potential E 0 (4-5) for americium should be higher than E 0 (4-5) for plutonium. A relatively small oxidizing potential E 0 (4-5) for curium speaks about principle possibility of production of five-valent curium in solution, though it is less stable than the six-valent one. Oxidizing potential corresponding to transition of three-valent californium into the four-valent state should be less than the value adopted in literature. A relatively small oxidizing potential of californium E 0 (4-5) speaks about possible existence of five-valent californium in solution

  8. Quantum Chemical Modeling of Enzymatic Reactions: The Case of Decarboxylation.

    Science.gov (United States)

    Liao, Rong-Zhen; Yu, Jian-Guo; Himo, Fahmi

    2011-05-10

    We present a systematic study of the decarboxylation step of the enzyme aspartate decarboxylase with the purpose of assessing the quantum chemical cluster approach for modeling this important class of decarboxylase enzymes. Active site models ranging in size from 27 to 220 atoms are designed, and the barrier and reaction energy of this step are evaluated. To model the enzyme surrounding, homogeneous polarizable medium techniques are used with several dielectric constants. The main conclusion is that when the active site model reaches a certain size, the solvation effects from the surroundings saturate. Similar results have previously been obtained from systematic studies of other classes of enzymes, suggesting that they are of a quite general nature.

  9. Quantum chemical prediction of antennae structures in lanthanide complexes

    International Nuclear Information System (INIS)

    Ottonelli, M.; Musso, G.F.; Rizzo, F.; Dellepiane, G.; Porzio, W.; Destri, S.

    2008-01-01

    In this paper the quantum chemical semiempirical procedure recently proposed by us to predict ground- and excited-state geometries of lanthanide complexes, the pseudo coordination centre method (PCC), is preliminarily compared with the semiempirical sparkle model for the calculation of lanthanide complexes (SMLC). Contrary to the SMLC method, where the rare-earth ion is replaced by a reparameterized sparkle atom, in our approach we replace it with a metal ion which is already present in the chosen semiempirical parameterization. This implies that in the optimization of the geometry of the complexes a different weight is implicitly given to the complex region including the rare-earth ion and its neighbour atoms with respect to the region of the ligands aggregate. As a consequence our approach is expected to reproduce better than the SMLC one the geometry of the ligands aggregate embedded in the complex, while the contrary happens for the coordination distances

  10. 77 FR 37839 - Veterans' Group Life Insurance (VGLI) No-Health Period Extension

    Science.gov (United States)

    2012-06-25

    ... DEPARTMENT OF VETERANS AFFAIRS 38 CFR Part 9 RIN 2900-AO24 Veterans' Group Life Insurance (VGLI) No-Health Period Extension AGENCY: Department of Veterans Affairs. ACTION: Proposed rule. SUMMARY... Veterans' Group Life Insurance (VGLI) to extend to 240 days the current 120-day ``no-health'' period during...

  11. Extension of the Poincaré group with half-integer spin generators: hypergravity and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Fuentealba, Oscar [Centro de Estudios Científicos (CECs), Av. Arturo Prat 514, Valdivia (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Matulich, Javier; Troncoso, Ricardo [Centro de Estudios Científicos (CECs), Av. Arturo Prat 514, Valdivia (Chile)

    2015-09-01

    An extension of the Poincaré group with half-integer spin generators is explicitly constructed. We start discussing the case of three spacetime dimensions, and as an application, it is shown that hypergravity can be formulated so as to incorporate this structure as its local gauge symmetry. Since the algebra admits a nontrivial Casimir operator, the theory can be described in terms of gauge fields associated to the extension of the Poincaré group with a Chern-Simons action. The algebra is also shown to admit an infinite-dimensional non-linear extension, that in the case of fermionic spin-3/2 generators, corresponds to a subset of a contraction of two copies of WB{sub 2}. Finally, we show how the Poincaré group can be extended with half-integer spin generators for d≥3 dimensions.

  12. Development and new applications of quantum chemical simulation methodology

    International Nuclear Information System (INIS)

    Weiss, A. K. H.

    2012-01-01

    The Division of Theoretical Chemistry at the University of Innsbruck is focused on the study of chemical compounds in aqueous solution, in terms of mainly hybrid quantum mechanical / molecular mechanical molecular dynamics simulations (QM/MM MD). Besides the standard means of data analysis employed for such simulations, this study presents several advanced and capable algorithms for the description of structural and dynamic properties of the simulated species and its hydration. The first part of this thesis further presents selected exemplary simulations, in particular a comparative study of Formamide and N-methylformamide, Guanidinium, and Urea. An included review article further summarizes the major advances of these studies. The computer programs developed in the course of this thesis are by now well established in the research field. The second part of this study presents the theory and a development guide for a quantum chemical program, QuMuLuS, that is by now used as a QM program for recent QM/MM simulations at the division. In its course, this part presents newly developed algorithms for electron integral evaluation and point charge embedding. This program is validated in terms of benchmark computations. The associated theory is presented on a detailed level, to serve as a source for contemporary and future studies in the division. In the third and final part, further investigations of related topics are addressed. This covers additional schemes of molecular simulation analysis, new software, as well as a mathematical investigation of a non-standard two-electron integral. (author)

  13. Characterization of heterocyclic rings through quantum chemical topology.

    Science.gov (United States)

    Griffiths, Mark Z; Popelier, Paul L A

    2013-07-22

    Five-membered rings are found in a myriad of molecules important in a wide range of areas such as catalysis, nutrition, and drug and agrochemical design. Systematic insight into their largely unexplored chemical space benefits from first principle calculations presented here. This study comprehensively investigates a grand total of 764 different rings, all geometry optimized at the B3LYP/6-311+G(2d,p) level, from the perspective of Quantum Chemical Topology (QCT). For the first time, a 3D space of local topological properties was introduced, in order to characterize rings compactly. This space is called RCP space, after the so-called ring critical point. This space is analogous to BCP space, named after the bond critical point, which compactly and successfully characterizes a chemical bond. The relative positions of the rings in RCP space are determined by the nature of the ring scaffold, such as the heteroatoms within the ring or the number of π-bonds. The summed atomic QCT charges of the five ring atoms revealed five features (number and type of heteroatom, number of π-bonds, substituent and substitution site) that dictate a ring's net charge. Each feature independently contributes toward a ring's net charge. Each substituent has its own distinct and systematic effect on the ring's net charge, irrespective of the ring scaffold. Therefore, this work proves the possibility of designing a ring with specific properties by fine-tuning it through manipulation of these five features.

  14. The ASME Section 11 Special Working Group On Plant Life Extension

    International Nuclear Information System (INIS)

    Katz, L.R.

    1990-01-01

    The codes and standards applicable to plant life extension have not been identified in the U.S. at this time. However, several initiatives have been taken to establish specific codes and standards pertaining to nuclear plant life extension (PLEX). One of these initiatives, sponsored by ASME, is the Section XI Special Working Group on Plant Life Extension (SWG-PLEX). The SWG-PLEX reports to the ASME Section XI Subcommittee and is responsible for recommending or drafting rules and requirements for modifying Section XI to accommodate age-related degradation to support nuclear plant life extension. This paper summarizes the results and reports the activities of the SWG-PLEX during the 1989/1990 period

  15. Extensive Validation of the Pain Disability Index in 3 Groups of Patients With Musculoskeletal Pain

    NARCIS (Netherlands)

    Soer, Remko; Koke, Albere J. A.; Vroomen, C.A.J.; Stegeman, Patrick; Smeets, Rob J. E. M.; Coppes, Maarten H.; Reneman, Michiel F.

    2013-01-01

    Study Design. A cross-sectional study design was performed. Objective. To validate the pain disability index (PDI) extensively in 3 groups of patients with musculoskeletal pain. Summary of Background Data. The PDI is a widely used and studied instrument for disability related to various pain

  16. Empirical, thermodynamic and quantum-chemical investigations of inclusion complexation between flavanones and (2-hydroxypropyl)-cyclodextrins.

    Science.gov (United States)

    Liu, Benguo; Li, Wei; Nguyen, Tien An; Zhao, Jian

    2012-09-15

    The inclusion complexation of (2-hydroxypropyl)-cyclodextrins with flavanones was investigated by phase solubility measurements, as well as thermodynamic and quantum chemical methods. Inclusion complexes were formed between (2-hydroxypropyl)-α-cyclodextrin (HP-α-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD), (2-hydroxypropyl)-γ-cyclodextrin (HP-γ-CD) and β-cyclodextrin (β-CD) and four flavanones (naringenin, naringin, hesperetin and dihydromyricetin) in aqueous solutions and their phase solubility was determined. For all the flavanones, the stability constants of their complexes formed with different CDs followed the rank order: HP-β-CD (MW 1540)>HP-β-CD (MW 1460)>HP-β-CD (MW 1380)>β-CD>HP-γ-CD>HP-α-CD. Experimental results and quantum chemical calculations showed that the ability of flavanones to form inclusion complex with (2-hydroxypropyl)-cyclodextrins was determined by both the steric effect and hydrophobicity of the flavanones. For flavanones that have similar molecular volumes, the hydrophobicity of the molecule was the main determining factor of its ability to form inclusion complexes with HP-β-CD, and the hydrophobicity parameter Log P is highly correlated with the stability constant of the complexes. Results of thermodynamic study demonstrated that hydrophobic interaction is the main driving force for the formation process of the flavanone-CD inclusion complexes. Quantum chemical analysis of the most active hydroxyl groups and HOMO (the highest occupied molecular orbital) showed that the B ring of the flavanones was most likely involved in hydrogen bonding with the side groups in the cavity of the CDs, through which the inclusion complex was stabilised. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Quantum-chemical study of hydride transfer in catalytic transformation of paraffins on zeolites

    NARCIS (Netherlands)

    Kazansky, V.B.; Frash, M.V.; Santen, van R.A.; Chon, H.; Ihm, S.-K.; Uh, Y.S.

    1997-01-01

    Ab initio quantum-chemical cluster calculations demonstrate that the activated complexes of hydride transfer reaction in catalytic transformation of paraffins on zeolites very much resembles adsorbed nonclassical carbonium ions. The calculated activation energies for reactions involving propane and

  18. Recent developments of the quantum chemical cluster approach for modeling enzyme reactions.

    Science.gov (United States)

    Siegbahn, Per E M; Himo, Fahmi

    2009-06-01

    The quantum chemical cluster approach for modeling enzyme reactions is reviewed. Recent applications have used cluster models much larger than before which have given new modeling insights. One important and rather surprising feature is the fast convergence with cluster size of the energetics of the reactions. Even for reactions with significant charge separation it has in some cases been possible to obtain full convergence in the sense that dielectric cavity effects from outside the cluster do not contribute to any significant extent. Direct comparisons between quantum mechanics (QM)-only and QM/molecular mechanics (MM) calculations for quite large clusters in a case where the results differ significantly have shown that care has to be taken when using the QM/MM approach where there is strong charge polarization. Insights from the methods used, generally hybrid density functional methods, have also led to possibilities to give reasonable error limits for the results. Examples are finally given from the most extensive study using the cluster model, the one of oxygen formation at the oxygen-evolving complex in photosystem II.

  19. Quantum chemical approaches: semiempirical molecular orbital and hybrid quantum mechanical/molecular mechanical techniques.

    Science.gov (United States)

    Bryce, Richard A; Hillier, Ian H

    2014-01-01

    The use of computational quantum chemical methods to aid drug discovery is surveyed. An overview of the various computational models spanning ab initio, density function theory, semiempirical molecular orbital (MO), and hybrid quantum mechanical (QM)/molecular mechanical (MM) methods is given and their strengths and weaknesses are highlighted, focussing on the challenge of obtaining the accuracy essential for them to make a meaningful contribution to drug discovery. Particular attention is given to hybrid QM/MM and semiempirical MO methods which have the potential to yield the necessary accurate predictions of macromolecular structure and reactivity. These methods are shown to have advanced the study of many aspects of substrate-ligand interactions relevant to drug discovery. Thus, the successful parametrization of semiempirical MO methods and QM/MM methods can be used to model noncovalent substrate-protein interactions, and to lead to improved scoring functions. QM/MM methods can be used in crystal structure refinement and are particularly valuable for modelling covalent protein-ligand interactions and can thus aid the design of transition state analogues. An extensive collection of examples from the areas of metalloenzyme structure, enzyme inhibition, and ligand binding affinities and scoring functions are used to illustrate the power of these techniques.

  20. The Nature of the Interactions in Triethanolammonium-Based Ionic Liquids. A Quantum Chemical Study.

    Science.gov (United States)

    Fedorova, Irina V; Safonova, Lyubov P

    2018-05-10

    Structural features and interionic interactions play a crucial role in determining the overall stability of ionic liquids and their physicochemical properties. Therefore, we performed high-level quantum-chemical study of different cation-anion pairs representing the building units of protic ionic liquids based on triethanolammonium cation and anions of sulfuric, nitric, phosphoric, and phosphorus acids to provide essential insight into these phenomena at the molecular level. It was shown that every structure is stabilized through multiple H bonds between the protons in the N-H and O-H groups of the cation and different oxygen atoms of the anion acid. Using atoms in molecules topological parameters and natural bond orbital analysis, we determined the nature and strength of these interactions. Our calculations suggest that the N-H group of the cation has more proton donor-like character than the O-H group that makes the N-H···O hydrogen bonds stronger. A close relation between the binding energies of these ion pairs and experimental melting points was established: the smaller the absolute value of the binding energy between ions, the lower is the melting point.

  1. Conformational, structural, vibrational and quantum chemical analysis on 4-aminobenzohydrazide and 4-hydroxybenzohydrazide--a comparative study.

    Science.gov (United States)

    Arjunan, V; Jayaprakash, A; Carthigayan, K; Periandy, S; Mohan, S

    2013-05-01

    Experimental and theoretical quantum chemical studies were carried out on 4-hydroxybenzohydrazide (4HBH) and 4-aminobenzohydrazide (4ABH) using FTIR and FT-Raman spectral data. The structural characteristics and vibrational spectroscopic analysis were carried performed by quantum chemical methods with the hybrid exchange-correlation functional B3LYP using 6-31G(**), 6-311++G(**) and aug-cc-pVDZ basis sets. The most stable conformer of the title compounds have been determined from the analysis of potential energy surface. The stable molecular geometries, electronic and thermodynamic parameters, IR intensities, harmonic vibrational frequencies, depolarisation ratio and Raman intensities have been computed. Molecular electrostatic potential and frontier molecular orbitals were constructed to understand the electronic properties. The potential energy distributions (PEDs) were calculated to explain the mixing of fundamental modes. The theoretical geometrical parameters and the fundamental frequencies were compared with the experimental. The interactions of hydroxy and amino group substitutions on the characteristic vibrations of the ring and hydrazide group have been analysed. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. [Effects of Meek skin grafting on patients with extensive deep burn at different age groups].

    Science.gov (United States)

    Di, H P; Niu, X H; Li, Q; Li, X L; Xue, J D; Cao, D Y; Han, D W; Xia, C D

    2017-03-20

    Objective: To investigate the effect of Meek skin grafting on patients with extensive deep burn at different age groups. Methods: Eighty-four patients with extensive deep burns conforming to the study criteria were hospitalized in our unit from April 2011 to April 2015. Patients were divided into children group (C, with age less than 12 years old), young and middle-aged group (YM, with age more than 18 years and less than 50 years old), and old age group (O, with age more than 55 years old) according to age, with 28 patients in each group. All patients received Meek skin grafting treatment. The use of autologous skin area, operation time, wound healing time, and hospitalization time were recorded. The survival rate of skin graft on post operation day 7, complete wound healing rate in post treatment week 2, and the mortality were calculated. Data were processed with one-way analysis of variance, t test, and χ (2) test. Results: The use of autologous skin area of patients in group C was (5.1±1.0)% total body surface area (TBSA), significantly less than (8.3±1.0)%TBSA and (8.3±1.4)%TBSA in groups YM and O, respectively (with t values 32.900 and 52.624, respectively, P values below 0.05). The operation time, wound healing time, and hospitalization time of patients in group C were (1.368±0.562) h, (9.6±0.6) and (32±11) d, significantly shorter than those in group YM [(3.235±0.011) h, (16.9±2.6) and (48±12) d, respectively] and group O [(3.692±0.481) h, (17.3±2.6) and (46±13) d, respectively, with t values from 4.350 to 21.160, P values below 0.05]. The survival rate of skin graft of patients on post operation day 7 in group C was (92±15)%, significantly higher than (81±10)% and (72±12)% in groups YM and O, respectively (with t values 5.509 and 3.229, respectively, P values below 0.05). The above indexes in groups YM and O were similar (with t values from 0.576 to 22.958, P values above 0.05). Complete wound healing rate in post treatment week 2 and the

  3. Molecular Structure of Phenytoin: NMR, UV-Vis and Quantum Chemical Calculations

    Directory of Open Access Journals (Sweden)

    Raluca Luchian

    2015-12-01

    Full Text Available Due to the presence of the carbonyl and imide groups in the structure of 5,5-diphenylhydantoin (DPH, the possibility for this compound to be involved in hydrogen bonding intermolecular interactions is obvious. Even though such interactions are presumably responsible for the mechanism of action of this drug, however, to the best of our knowledge, the self-hydrogen bonding interactions between the DPH monomers have not been addressed till now. Furthermore, studies reporting on the spectroscopic characteristics of this molecule are scarcely reported in the literature. Here we report on the possible dimers of DPH, investigated by quantum chemical calculations at B3LYP/6-31+G(2d,2p level of theory. Twelve unique DPH dimers were structurally optimized in gas-phase, as well as in ethanol and DMSO and then were used to compute the population-averaged UV-Vis and NMR spectra using Boltzmann statistics. UV-Vis and NMR techniques were employed to assess experimentally the spectroscopical response of this compound. DFT calculations are also used to investigate the structural transformations between the solid and liquid phase, as well as for describing the electronic transitions and for the assignment of NMR spectra of DPH.

  4. Quantum chemical evaluation for the stability of liquid sodium containing titanium nanoparticles

    International Nuclear Information System (INIS)

    Suzuki, Ai; Inaba, Kenji; Ishizawa, Yukie; Miura, Ryuji; Hatakeyama, Nozomu; Miyamoto, Akira; Saito, Jun-ichi; Ara, Kuniaki

    2015-01-01

    Recently, liquid sodium containing titanium nanoparticles (LSnanop) have attracted considerable attention. In this study, suspension state of Ti nanoparticle in liquid sodium was quantum chemically evaluated. The atomic interaction between Ti nanoparticles and sodium atoms in the liquid sodium medium was investigated. There were some literatures which gained quantum chemical insight into a nanoparticle with the surrounding sodium atom. However, liquid sodium medium itself together with a Ti nanoparticle under the realistic temperature has not yet been investigated theoretically. To overcome the problem of conventional theoretical method, we applied computationally low-load Tight Binding Quantum Chemical Molecular Dynamics (TB-QCMD) calculation method to investigate the suspension state of the Ti nanoparticle in liquid sodium metal. (author)

  5. Quantum chemical investigation of levofloxacin-boron complexes: A computational approach

    Science.gov (United States)

    Sayin, Koray; Karakaş, Duran

    2018-04-01

    Quantum chemical calculations are performed over some boron complexes with levofloxacin. Boron complex with fluorine atoms are optimized at three different methods (HF, B3LYP and M062X) with 6-31 + G(d) basis set. The best level is determined as M062X/6-31 + G(d) by comparison of experimental and calculated results of complex (1). The other complexes are optimized by using the best level. Structural properties, IR and NMR spectrum are examined in detail. Biological activities of mentioned complexes are investigated by some quantum chemical descriptors and molecular docking analyses. As a result, biological activities of complex (2) and (4) are close to each other and higher than those of other complexes. Additionally, NLO properties of mentioned complexes are investigated by some quantum chemical parameters. It is found that complex (3) is the best candidate for NLO applications.

  6. Electron-beam generated porous dextran gels: experimental and quantum chemical studies.

    Science.gov (United States)

    Naumov, Sergej; Knolle, Wolfgang; Becher, Jana; Schnabelrauch, Matthias; Reichelt, Senta

    2014-06-01

    The aim of this work was to investigate the reaction mechanism of electron-beam generated macroporous dextran cryogels by quantum chemical calculation and electron paramagnetic resonance measurements. Electron-beam radiation was used to initiate the cross-linking reaction of methacrylated dextran in semifrozen aqueous solutions. The pore morphology of the resulting cryogels was visualized by scanning electron microscopy. Quantum chemical calculations and electron paramagnetic resonance studies provided information on the most probable reaction pathway and the chain growth radicals. The most probable reaction pathway was a ring opening reaction and the addition of a C-atom to the double-bond of the methacrylated dextran molecule. First detailed quantum chemical calculation on the reaction mechanism of electron-beam initiated cross-linking reaction of methacrylated dextran are presented.

  7. Quantum spaces, central extensions of Lie groups and related quantum field theories

    Science.gov (United States)

    Poulain, Timothé; Wallet, Jean-Christophe

    2018-02-01

    Quantum spaces with su(2) noncommutativity can be modelled by using a family of SO(3)-equivariant differential *-representations. The quantization maps are determined from the combination of the Wigner theorem for SU(2) with the polar decomposition of the quantized plane waves. A tracial star-product, equivalent to the Kontsevich product for the Poisson manifold dual to su(2) is obtained from a subfamily of differential *-representations. Noncommutative (scalar) field theories free from UV/IR mixing and whose commutative limit coincides with the usual ϕ 4 theory on ℛ3 are presented. A generalization of the construction to semi-simple possibly non simply connected Lie groups based on their central extensions by suitable abelian Lie groups is discussed. Based on a talk presented by Poulain T at the XXVth International Conference on Integrable Systems and Quantum symmetries (ISQS-25), Prague, June 6-10 2017.

  8. Quantum chemical aided prediction of the thermal decomposition mechanisms and temperatures of ionic liquids

    International Nuclear Information System (INIS)

    Kroon, Maaike C.; Buijs, Wim; Peters, Cor J.; Witkamp, Geert-Jan

    2007-01-01

    The long-term thermal stability of ionic liquids is of utmost importance for their industrial application. Although the thermal decomposition temperatures of various ionic liquids have been measured previously, experimental data on the thermal decomposition mechanisms and kinetics are scarce. It is desirable to develop quantitative chemical tools that can predict thermal decomposition mechanisms and temperatures (kinetics) of ionic liquids. In this work ab initio quantum chemical calculations (DFT-B3LYP) have been used to predict thermal decomposition mechanisms, temperatures and the activation energies of the thermal breakdown reactions. These quantum chemical calculations proved to be an excellent method to predict the thermal stability of various ionic liquids

  9. On the structure of Selmer groups of $p$-ordinary modular forms over $\\mathbf{Z}_p$-extensions

    OpenAIRE

    Kidwell, Keenan

    2016-01-01

    We prove analogues of the major algebraic results of Greenberg-Vatsal for Selmer groups of $p$-ordinary newforms over $\\mathbf{Z}_p$-extensions which may be neither cyclotomic nor anticyclotomic, under a number of technical hypotheses, including a cotorsion assumption on the Selmer groups. The main complication which arises in our work is the possible presence of finite primes which can split completely in the $\\mathbf{Z}_p$-extension being considered, resulting in the local cohomology groups...

  10. The use of quantum chemically derived descriptors for QSAR modelling of reductive dehalogenation of aromatic compounds

    NARCIS (Netherlands)

    Rorije E; Richter J; Peijnenburg WJGM; ECO; IHE Delft

    1994-01-01

    In this study, quantum-chemically derived parameters are developed for a limited number of halogenated aromatic compounds to model the anaerobic reductive dehalogenation reaction rate constants of these compounds. It is shown that due to the heterogeneity of the set of compounds used, no single

  11. Complementing high-throughput X-ray powder diffraction data with quantum-chemical calculations

    DEFF Research Database (Denmark)

    Naelapaa, Kaisa; van de Streek, Jacco; Rantanen, Jukka

    2012-01-01

    of piroxicam form III. These combined experimental/quantum-chemical methods can provide access to reliable structural information in the course of an intensive experimentally based solid-form screening activity or in other circumstances wherein single crystals might never be viable, for example, for polymorphs...

  12. Electrochemical and Quantum Chemical Study of Reactivity of Orthophthalaldehyde with Aliphatic Primary Amines

    Czech Academy of Sciences Publication Activity Database

    Donkeng Dazie, Joel; Liška, Alan; Ludvík, Jiří

    2016-01-01

    Roč. 163, č. 9 (2016), G127-G132 ISSN 0013-4651 R&D Projects: GA ČR GA13-21704S Institutional support: RVO:61388955 Keywords : electrochemistry * quantum chemical study * amines Subject RIV: CG - Electrochemistry Impact factor: 3.259, year: 2016

  13. Will-Nordtvedt PPN formalism applied to renormalization group extensions of general relativity

    Science.gov (United States)

    Toniato, Júnior D.; Rodrigues, Davi C.; de Almeida, Álefe O. F.; Bertini, Nicolas

    2017-09-01

    We apply the full Will-Nordtvedt version of the parametrized post-Newtonian (PPN) formalism to a class of general relativity extensions that are based on nontrivial renormalization group (RG) effects at large scales. We focus on a class of models in which the gravitational coupling constant G is correlated with the Newtonian potential. A previous PPN analysis considered a specific realization of the RG effects, and only within the Eddington-Robertson-Schiff version of the PPN formalism, which is a less complete and robust PPN formulation. Here we find stronger, more precise bounds, and with less assumptions. We also consider the external potential effect (EPE), which is an effect that is intrinsic to this framework and depends on the system environment (it has some qualitative similarities to the screening mechanisms of modified gravity theories). We find a single particular RG realization that is not affected by the EPE. Some physical systems have been pointed out as candidates for measuring the possible RG effects in gravity at large scales; for any of them the Solar System bounds need to be considered.

  14. Quantum-chemical analysis of formation reactions of Со2+ complexes

    Directory of Open Access Journals (Sweden)

    Viktor F. Vargalyuk

    2017-11-01

    Full Text Available Based on the analysis of quantum chemical calculations results (GAMESS, density functional theory, B3LYP method as to coordination compounds of Co2+ions with H2O, NH3, OH–, F–, Cl–, Br–, I–, CN–, Ac–, Ak– generally given by [Co(H2O6–nLn]2+nx, it has been demonstrated that within the selected series of ligands, there is no correlation between the amount of energy of monosubstituted cobalt aqua complexes formation(∆Е and pK1,just like between the effective nuclear charge of the central atom (z*Со and pK1. According to the behavior of ∆Е and z*Со,we identified two groups of ligands. The first group (OH–, F–, Ac–, Ak–, CN–, NH3 demonstrates logical ∆Е decrease caused by the growth of z*Со. On the contrary, the second group (Cl–, Br–, I– demonstrates ∆Е increase caused by the growth of z*Со. This phenomenon is explained by the change in electronegativity and polarizability of donor atoms in groups and periods of the periodic table. It is established that linear correlations given by lgK = A + B·z*Со can be actualized only for complexes having ligands with similar donor atoms. Referring to the literature on stepwise complex formation of hydroxide, amine and chloride cobalt complexes in combination with z*Со calculations results, we determined A and B constants of lgK, z*Со-correlations for the atoms of oxygen (30.2, –17.7; nitrogen (125.4, –69.9 and chlorine (–6.3, 5.8. The existence of the detected correlation series enables us to lean on lgK,z*М–dependence parameters for the fixed donor atom and to determine Kn values for various complexes with complex-based ligands using calculations and z*М data. This applies to complexes having central atoms of the same nature as well as simple monodentate ligands. The mentioned approach was used to calculate the stability constants for acrylate cobalt complexes (lgK1 = 1.2 и lgК2 = 4.3, which are not covered in literature.

  15. Extensive validation of the pain disability index in 3 groups of patients with musculoskeletal pain.

    Science.gov (United States)

    Soer, Remko; Köke, Albère J A; Vroomen, Patrick C A J; Stegeman, Patrick; Smeets, Rob J E M; Coppes, Maarten H; Reneman, Michiel F

    2013-04-20

    A cross-sectional study design was performed. To validate the pain disability index (PDI) extensively in 3 groups of patients with musculoskeletal pain. The PDI is a widely used and studied instrument for disability related to various pain syndromes, although there is conflicting evidence concerning factor structure, test-retest reliability, and missing items. Additionally, an official translation of the Dutch language version has never been performed. For reliability, internal consistency, factor structure, test-retest reliability and measurement error were calculated. Validity was tested with hypothesized correlations with pain intensity, kinesiophobia, Rand-36 subscales, Depression, Roland-Morris Disability Questionnaire, Quality of Life, and Work Status. Structural validity was tested with independent backward translation and approval from the original authors. One hundred seventy-eight patients with acute back pain, 425 patients with chronic low back pain and 365 with widespread pain were included. Internal consistency of the PDI was good. One factor was identified with factor analyses. Test-retest reliability was good for the PDI (intraclass correlation coefficient, 0.76). Standard error of measurement was 6.5 points and smallest detectable change was 17.9 points. Little correlations between the PDI were observed with kinesiophobia and depression, fair correlations with pain intensity, work status, and vitality and moderate correlations with the Rand-36 subscales and the Roland-Morris Disability Questionnaire. The PDI-Dutch language version is internally consistent as a 1-factor structure, and test-retest reliable. Missing items seem high in sexual and professional items. Using the PDI as a 2-factor questionnaire has no additional value and is unreliable.

  16. Quantum chemical studies on the corrosion inhibition of some sulphonamides on mild steel in acidic medium

    International Nuclear Information System (INIS)

    Arslan, Taner; Kandemirli, Fatma; Ebenso, Eno E.; Love, Ian; Alemu, Hailemichael

    2009-01-01

    Quantum chemical calculations using the density functional theory (DFT) and some semi-empirical methods were performed on four sulphonamides (sulfaguanidine, sulfamethazine, sulfamethoxazole and sulfadiazine) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies. The results of the quantum chemical calculations and experimental %IE were subjected to correlation analysis and indicate that their inhibition effect are closely related to E HOMO , E LUMO , hardness, polarizability, dipole moment and charges. The %IE increased with increase in the E HOMO and decrease in E HOMO - E LUMO . The negative sign of the E HOMO values and other kinetic and thermodynamic parameters indicates that the data obtained support physical adsorption mechanism

  17. Quantum chemical modeling of enzymatic reactions: the case of 4-oxalocrotonate tautomerase.

    Science.gov (United States)

    Sevastik, Robin; Himo, Fahmi

    2007-12-01

    The reaction mechanism of 4-oxalocrotonate tautomerase (4-OT) is studied using the density functional theory method B3LYP. This enzyme catalyzes the isomerisation of unconjugated alpha-keto acids to their conjugated isomers. Two different quantum chemical models of the active site are devised and the potential energy curves for the reaction are computed. The calculations support the proposed reaction mechanism in which Pro-1 acts as a base to shuttle a proton from the C3 to the C5 position of the substrate. The first step (proton transfer from C3 to proline) is shown to be the rate-limiting step. The energy of the charge-separated intermediate (protonated proline-deprotonated substrate) is calculated to be quite low, in accordance with measured pKa values. The results of the two models are used to evaluate the methodology employed in modeling enzyme active sites using quantum chemical cluster models.

  18. Combined Docking with Classical Force Field and Quantum Chemical Semiempirical Method PM7

    Directory of Open Access Journals (Sweden)

    A. V. Sulimov

    2017-01-01

    Full Text Available Results of the combined use of the classical force field and the recent quantum chemical PM7 method for docking are presented. Initially the gridless docking of a flexible low molecular weight ligand into the rigid target protein is performed with the energy function calculated in the MMFF94 force field with implicit water solvent in the PCM model. Among several hundred thousand local minima, which are found in the docking procedure, about eight thousand lowest energy minima are chosen and then energies of these minima are recalculated with the recent quantum chemical semiempirical PM7 method. This procedure is applied to 16 test complexes with different proteins and ligands. For almost all test complexes such energy recalculation results in the global energy minimum configuration corresponding to the ligand pose near the native ligand position in the crystalized protein-ligand complex. A significant improvement of the ligand positioning accuracy comparing with MMFF94 energy calculations is demonstrated.

  19. Combined Docking with Classical Force Field and Quantum Chemical Semiempirical Method PM7.

    Science.gov (United States)

    Sulimov, A V; Kutov, D C; Katkova, E V; Sulimov, V B

    2017-01-01

    Results of the combined use of the classical force field and the recent quantum chemical PM7 method for docking are presented. Initially the gridless docking of a flexible low molecular weight ligand into the rigid target protein is performed with the energy function calculated in the MMFF94 force field with implicit water solvent in the PCM model. Among several hundred thousand local minima, which are found in the docking procedure, about eight thousand lowest energy minima are chosen and then energies of these minima are recalculated with the recent quantum chemical semiempirical PM7 method. This procedure is applied to 16 test complexes with different proteins and ligands. For almost all test complexes such energy recalculation results in the global energy minimum configuration corresponding to the ligand pose near the native ligand position in the crystalized protein-ligand complex. A significant improvement of the ligand positioning accuracy comparing with MMFF94 energy calculations is demonstrated.

  20. Oxygen-vacancy defects on BaTiO3 (001) surface: a quantum chemical study

    International Nuclear Information System (INIS)

    Duque, Carlos; Stashans, Arvids

    2003-01-01

    A quantum-chemical study of technologically important BaTiO 3 crystal and oxygen-vacancy defects on its (001) surface is reported in the present work. The computations are made using a quantum-chemical method developed for periodic systems (crystals), which is based on the Hartree-Fock theory. The atomic rearrangement due to the surface creation is obtained for a pure BaTiO 3 by means of the periodic large unit cell (LUC) model and using an automated geometry optimisation procedure. The same technique is employed to study the electronic and structural properties of the material due to the presence of an O vacancy and F centre (two electrons trapped in an oxygen vacancy). The computations are carried out for both cubic and tetragonal lattices

  1. Quantum chemical modeling of antioxidant activity of glutathione interacting with hydroxyl- and superoxide anion radicals

    Directory of Open Access Journals (Sweden)

    N. V. Solovyova

    2015-04-01

    Full Text Available Following the analysis of the results of quantum chemical simulation of interaction between a GSH molecule and oxygen radicals •ОН and •ООˉ, it was found that it takes place through the acid-base mechanism, where GSH acts as a base towards •ОН, and as an acid towards •ООˉ. The results of quantum chemical calculations (electron density redistribution, energy characteristics were correlated at the time of interaction of a GSH molecule with •ОН and •ООˉ with a change of macroscopic parameters of the process of free oxygen radical electroreduction in the presence of GSH (potential and maximum current of reduction waves, which is a direct experimental macroscale evidence of results of the conducted nanoscale theoretical simulation.

  2. Mechanisms of gas phase decomposition of C-nitro compounds from quantum chemical data

    International Nuclear Information System (INIS)

    Khrapkovskii, Grigorii M; Shamov, Alexander G; Nikolaeva, E V; Chachkov, D V

    2009-01-01

    Data on the mechanisms of gas-phase monomolecular decomposition of nitroalkanes, nitroalkenes and nitroarenes obtained using modern quantum chemical methods are described systematically. The attention is focused on the discussion of multistage decomposition of nitro compounds to elementary experimentally observed products. Characteristic features of competition of different mechanisms and the effect of molecular structure on the change in the Arrhenius parameters of the primary reaction step are considered.

  3. Mechanisms of gas phase decomposition of C-nitro compounds from quantum chemical data

    Energy Technology Data Exchange (ETDEWEB)

    Khrapkovskii, Grigorii M; Shamov, Alexander G; Nikolaeva, E V; Chachkov, D V [Kazan State Technological University, Kazan (Russian Federation)

    2009-10-31

    Data on the mechanisms of gas-phase monomolecular decomposition of nitroalkanes, nitroalkenes and nitroarenes obtained using modern quantum chemical methods are described systematically. The attention is focused on the discussion of multistage decomposition of nitro compounds to elementary experimentally observed products. Characteristic features of competition of different mechanisms and the effect of molecular structure on the change in the Arrhenius parameters of the primary reaction step are considered.

  4. Molecular interactions of nucleic acid bases. A review of quantum-chemical studies

    Czech Academy of Sciences Publication Activity Database

    Šponer, Jiří; Hobza, Pavel

    2003-01-01

    Roč. 68, č. 12 (2003), s. 2231-2282 ISSN 0010-0765 R&D Projects: GA MŠk LN00A032; GA AV ČR IAA4040904 Grant - others:Wellcome Trust(GB) GR067507MF Institutional research plan: CEZ:AV0Z5004920; CEZ:AV0Z4040901 Keywords : DNA base pairs * initio quantum -chemical calculations * electron correlation Subject RIV: BO - Biophysics Impact factor: 1.041, year: 2003

  5. Chern-Simons action for inhomogeneous Virasoro group as extension of three dimensional flat gravity

    Energy Technology Data Exchange (ETDEWEB)

    Barnich, Glenn [Physique Théorique et Mathématique, Université Libre de Bruxelles and International Solvay Institutes, Campus Plaine C.P. 231, B-1050 Bruxelles (Belgium); Giribet, Gastón [Physique Théorique et Mathématique, Université Libre de Bruxelles and International Solvay Institutes, Campus Plaine C.P. 231, B-1050 Bruxelles (Belgium); Universidad de Buenos Aires FCEN-UBA and IFIBA-CONICET, Ciudad Universitaria, Pabellón I, 1428 Buenos Aires (Argentina); Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Leston, Mauricio [Instituto de Astronomía y Física del Espacio IAFE-CONICET, Ciudad Universitaria, Pabellón IAFE, C.C. 67 Suc. 28, 1428 Buenos Aires (Argentina)

    2015-07-15

    We initiate the study of a Chern-Simons action associated to the semi-direct sum of the Virasoro algebra with its coadjoint representation. This model extends the standard Chern-Simons formulation of three dimensional flat gravity and is similar to the higher-spin extension of three dimensional anti-de Sitter or flat gravity. The extension can also be constructed for the exotic but not for the cosmological constant deformation of flat gravity.

  6. Quantum chemical and spectroscopic analysis of calcium hydroxyapatite and related materials

    International Nuclear Information System (INIS)

    Khavryuchenko, V.D.; Khavryuchenko, O.V.; Lisnyak, V.V.

    2007-01-01

    Amorphous calcium hydroxyapatite was examined by vibrational spectroscopy (Raman and infra-red (IR)) and quantum chemical simulation techniques. The structures and vibrational (IR, Raman and inelastic neutron scattering) spectra of PO 4 3- ion, Ca 3 (PO 4 ) 2 , [Ca 3 (PO 4 ) 2 ] 3 , Ca 5 (PO 4 ) 3 OH, CaHPO 4 , [CaHPO 4 ] 2 , Ca 3 (PO 4 ) 2 .H 2 O, Ca 3 (PO 4 ) 2 .2H 2 O and Ca 3 (PO 4 ) 2 .3H 2 O clusters were quantum chemically simulated at ab initio and semiempirical levels of approximation. A complete coordinate analysis of the vibrational spectra was performed. The comparison of the theoretically simulated spectra with the experimental ones allows to identify correctly the phase composition of the amorphous calcium hydroxyapatite and related materials. The shape of the bands in the IR spectra of the hydroxoapatite can be used in order to characterize the structural properties of the material, e.g., the PO 4 3- ion status, the degree of hydrolysis of the material and the presence of hydrolysis products. - Graphical abstract: The structure of the quantum chemically optimized Ca 5 (PO 4 ) 3 (OH) cluster, which was used for vibrations spectra simulation

  7. Metal compounds in zeolites as active components of chemisorption and catalysis. Quantum chemical approach

    International Nuclear Information System (INIS)

    Zhidomirov, G.M.

    1996-01-01

    A short review of possible catalitic active sites associated with various types of metal species in zoolite is presented. The structural and electronic peculiarity of aluminum ions in zeolite lattice and their distribution in the lattice are discussed on the basis of quantum chemical calculations in connection with the formation of Broensted activity of zeolites. Various molecular models of Lewis Acid Sites associated the extra-lattice oxide-hydroxide aluminum species have been investigated by means of density functional model cluster calculations using CO molecule as a probe. Probable ways of formation of the selective oxidation center in FeZSM-5 by decomposition of dinitrogen monoxide have been studied by ab-initio quantum chemical calculations. The immediate oxidizing site is reasonably represented by the binuclear iron-hydroxide cluster with peroxo-like fragment located between iron atoms. Various probable intermediates of the selective oxidation center formation resulted from interaction of a hydroperoxide molecule with a lattice titanium ion in titanium silicalite have been investigated by quantum chemical calculations. It was concluded that this reaction requires essential structural reconstruction in the vicinity of the titanium ion. Probability of this structural reconstruction is discussed. Possible reasons of an electron-deficient and electron-enriched state of metal particles entrapped in zoolite cavities are discussed. Also, various probable molecular models of such modified metal particles in zeolite are considered

  8. Chemical Reactivity as Described by Quantum Chemical Methods

    Directory of Open Access Journals (Sweden)

    F. De Proft

    2002-04-01

    Full Text Available Abstract: Density Functional Theory is situated within the evolution of Quantum Chemistry as a facilitator of computations and a provider of new, chemical insights. The importance of the latter branch of DFT, conceptual DFT is highlighted following Parr's dictum "to calculate a molecule is not to understand it". An overview is given of the most important reactivity descriptors and the principles they are couched in. Examples are given on the evolution of the structure-property-wave function triangle which can be considered as the central paradigm of molecular quantum chemistry to (for many purposes a structure-property-density triangle. Both kinetic as well as thermodynamic aspects can be included when further linking reactivity to the property vertex. In the field of organic chemistry, the ab initio calculation of functional group properties and their use in studies on acidity and basicity is discussed together with the use of DFT descriptors to study the kinetics of SN2 reactions and the regioselectivity in Diels Alder reactions. Similarity in reactivity is illustrated via a study on peptide isosteres. In the field of inorganic chemistry non empirical studies of adsorption of small molecules in zeolite cages are discussed providing Henry constants and separation constants, the latter in remarkable good agreement with experiments. Possible refinements in a conceptual DFT context are presented. Finally an example from biochemistry is discussed : the influence of point mutations on the catalytic activity of subtilisin.

  9. A quantum-chemical perspective into low optical-gap polymers for highly-efficient organic solar cells

    KAUST Repository

    Risko, Chad; McGehee, Michael D.; Bré das, Jean-Luc

    2011-01-01

    in photocurrent generation. In this Perspective, we first present an overview of the application of quantum-chemical techniques to study the intrinsic material properties and molecular- and nano-scale processes involved in device operation. In the second part

  10. Quantum chemical studies on electronic structure and photodynamics of ruthenium complexes

    International Nuclear Information System (INIS)

    Freitag, L.

    2015-01-01

    Ruthenium complexes have found their way into many applications in the last decades. Among those, ruthenium polypyridyl compounds have been employed as light harvesting devices and photosensitisers in artificial photosynthesis and molecular photocatalysis. Ruthenium nitrosyl complexes are rapidly emerging as NO delivery agents to biological tissues with promising applications in anticancer photodynamic therapy, thanks to their ability to photorelease nitric oxide (NO). This thesis encompasses computational studies on reactivity, electronic structure, excited states and photodynamics of several ruthenium nitrosyl and polypyridyl complexes. The first part of the thesis deals with ruthenium nitrosyls. The cis-trans isomerisation mechanism of RuHIndNO, a ruthenium nitrosyl derivate of the prominent anti-cancer drug candidate KP1019, is investigated with density functional theory calculations. Next, the electronic structure of the ground and the first excited triplet state of RuHIndNO is studied with multiconfigurational methods including the density-matrix renormalisation group (DMRG). The obtained multiconfigurational wavefunctions and DMRG-based orbital entanglement analysis provides theoretical insight into the non-innocence of the NO ligand in nitrosyl complexes by describing the electron correlation in the Ru--NO bond and assigning oxidation states to the metal and the NO ligand. Another study is performed on excited states of ruthenium nitrosyl complexes with quantum chemical calculations and surface-hopping dynamics to obtain insights into the photodissociation mechanism of NO. The second part of this thesis is devoted to the excited states and photophysics of ruthenium polypyridyl complexes. Accurate excitation energies of tris(2,2-bipyridine)ruthenium (II), the prototype ruthenium polypyridyl are obtained with multiconfigurational calculations assisted by an orbital entanglement analysis. Subsequently, the effect of the ligand substitution on the photophysics

  11. Degradation of di(2-ethyl hexyl) phthalate by Fusarium culmorum: Kinetics, enzymatic activities and biodegradation pathway based on quantum chemical modelingpathway based on quantum chemical modeling

    International Nuclear Information System (INIS)

    Ahuactzin-Pérez, Miriam; Tlecuitl-Beristain, Saúl; García-Dávila, Jorge; González-Pérez, Manuel; Gutiérrez-Ruíz, María Concepción; Sánchez, Carmen

    2016-01-01

    Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics, and it is an environmental contaminant. The specific growth rate (μ), maximum biomass (X_m_a_x), biodegradation constant of DEHP (k), half-life (t_1_/_2) of DEHP biodegradation and removal efficiency of DEHP, esterase and laccase specific activities, and enzymatic yield parameters were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000 mg/L). The greatest μ and the largest X_m_a_x occurred in media supplemented with 1000 mg of DEHP/L. F. culmorum degraded 95% of the highest amount of DEHP tested (1000 mg/L) within 60 h of growth. The k and t_1_/_2 were 0.024 h"−"1 and 28 h, respectively, for both DEHP concentrations. The removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. Much higher specific esterase activity than specific laccase activity was observed in all media tested. The compounds of biodegradation of DEHP were identified by GC–MS. A DEHP biodegradation pathway by F. culmorum was proposed on the basis of the intermolecular flow of electrons of the identified intermediate compounds using quantum chemical modeling. DEHP was fully metabolized by F. culmorum with butanediol as the final product. This fungus offers great potential in bioremediation of environments polluted with DEHP. - Highlights: • F. culmorum degraded 95% of DEHP (1000 mg/L) within 60 h. • Removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. • DEHP was fully metabolized by F. culmorum, with butanediol as the final product. • A DEHP biodegradation pathway was proposed using on quantum chemical modeling.

  12. Degradation of di(2-ethyl hexyl) phthalate by Fusarium culmorum: Kinetics, enzymatic activities and biodegradation pathway based on quantum chemical modelingpathway based on quantum chemical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ahuactzin-Pérez, Miriam [Doctorado en Biología Experimental, Universidad Autónoma Metropolitana-Iztapalapa (UAM-I) (Mexico); Facultad de Agrobiología, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Tlaxcala (Mexico); Tlecuitl-Beristain, Saúl; García-Dávila, Jorge [Universidad Politécnica de Tlaxcala, San Pedro Xalcatzinco, Tepeyanco, Tlaxcala CP 90180 (Mexico); González-Pérez, Manuel [Universidad Popular Autónoma del Estado de Puebla, Puebla CP 72410 (Mexico); Gutiérrez-Ruíz, María Concepción [Departamento de Ciencias de la Salud, Universidad Autónoma Metropolitana-Iztapalapa, D.F (Mexico); Sánchez, Carmen, E-mail: sanher6@hotmail.com [Laboratory of Biotechnology, Research Centre for Biological Sciences, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Tlaxcala CP. 90062 (Mexico)

    2016-10-01

    Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics, and it is an environmental contaminant. The specific growth rate (μ), maximum biomass (X{sub max}), biodegradation constant of DEHP (k), half-life (t{sub 1/2}) of DEHP biodegradation and removal efficiency of DEHP, esterase and laccase specific activities, and enzymatic yield parameters were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000 mg/L). The greatest μ and the largest X{sub max} occurred in media supplemented with 1000 mg of DEHP/L. F. culmorum degraded 95% of the highest amount of DEHP tested (1000 mg/L) within 60 h of growth. The k and t{sub 1/2} were 0.024 h{sup −1} and 28 h, respectively, for both DEHP concentrations. The removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. Much higher specific esterase activity than specific laccase activity was observed in all media tested. The compounds of biodegradation of DEHP were identified by GC–MS. A DEHP biodegradation pathway by F. culmorum was proposed on the basis of the intermolecular flow of electrons of the identified intermediate compounds using quantum chemical modeling. DEHP was fully metabolized by F. culmorum with butanediol as the final product. This fungus offers great potential in bioremediation of environments polluted with DEHP. - Highlights: • F. culmorum degraded 95% of DEHP (1000 mg/L) within 60 h. • Removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. • DEHP was fully metabolized by F. culmorum, with butanediol as the final product. • A DEHP biodegradation pathway was proposed using on quantum chemical modeling.

  13. Evaluation of the catalytic mechanism of AICAR transformylase by pH-dependent kinetics, mutagenesis, and quantum chemical calculations.

    Science.gov (United States)

    Shim, J H; Wall, M; Benkovic, S J; Díaz, N; Suárez, D; Merz, K M

    2001-05-23

    The catalytic mechanism of 5-aminoimidazole-4-carboxamide ribonucleotide transformylase (AICAR Tfase) is evaluated with pH dependent kinetics, site-directed mutagenesis, and quantum chemical calculations. The chemistry step, represented by the burst rates, was not pH-dependent, which is consistent with our proposed mechanism that the 4-carboxamide of AICAR assists proton shuttling. Quantum chemical calculations on a model system of 5-amino-4-carboxamide imidazole (AICA) and formamide using the B3LYP/6-31G level of theory confirmed that the 4-carboxamide participated in the proton-shuttling mechanism. The result also indicated that the amide-assisted mechanism is concerted such that the proton transfers from the 5-amino group to the formamide are simultaneous with nucleophilic attack by the 5-amino group. Because the process does not lead to a kinetically stable intermediate, the intramolecular proton transfer from the 5-amino group through the 4-carboxamide to the formamide proceeds in the same transition state. Interestingly, the calculations predicted that protonation of the N3 of the imidazole of AICA would reduce the energy barrier significantly. However, the pK(a) of the imidazole of AICAR was determined to be 3.23 +/- 0.01 by NMR titration, and AICAR is likely to bind to the enzyme with its imidazole in the free base form. An alternative pathway was suggested by modeling Lys266 to have a hydrogen-bonding interaction with the N3 of the imidazole of AICAR. Lys266 has been implicated in catalysis based on mutagenesis studies and the recent X-ray structure of AICAR Tfase. The quantum chemical calculations on a model system that contains AICA complexed with CH3NH3+ as a mimic of the Lys residue confirmed that such an interaction lowered the activation energy of the reaction and likewise implicated the 4-carboxamide. To experimentally verify this hypothesis, we prepared the K266R mutant and found that its kcat is reduced by 150-fold from that of the wild type

  14. Extension of $b{sub f}$-continuous functions defined on a product of $b{sub f}$-groups

    Energy Technology Data Exchange (ETDEWEB)

    Sanchis, M.

    2017-07-01

    Let X be a bf -space and let G be a bf -group. By means of the exponential mapping we characterize when a bf -continuous function on X × G with values in a topologically complete sapce Z has a bf -continuous extension to β(X) × G. As a consequence we show that the product of a pseudocompact space and a bf -group is a bf -group. This result generalizes the fact that the product of a pseudocompact space and a pseudocompact group is pseudocompact. (Author)

  15. Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions

    Directory of Open Access Journals (Sweden)

    Masego Dibetsoe

    2015-08-01

    Full Text Available The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1, 2,3,9,10,16,17,23,24-octakis(octyloxy-29H,31H-phthalocyanine (Pc2, 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3 and 29H,31H-phthalocyanine (Pc4, and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1, 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2 and 2,3-naphthalocyanine (nP3 were investigated on the corrosion of aluminium (Al in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR. Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I− ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR

  16. Reference quantum chemical calculations on RNA base pairs directly involving the 2'-OH group of ribose

    Czech Academy of Sciences Publication Activity Database

    Šponer, Jiří; Zgarbová, M.; Jurečka, Petr; Riley, K.E.; Šponer, Judit E.; Hobza, Pavel

    2009-01-01

    Roč. 5, č. 4 (2009), s. 1166-1179 ISSN 1549-9618 R&D Projects: GA AV ČR(CZ) IAA400040802; GA AV ČR(CZ) IAA400550701; GA MŠk(CZ) LC06030; GA MŠk(CZ) LC512 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702; CEZ:AV0Z40550506 Keywords : RNA * ribose * quantum calculations Subject RIV: BO - Biophysics Impact factor: 4.804, year: 2009

  17. Elucidation of Mechanisms and Selectivities of Metal-Catalyzed Reactions using Quantum Chemical Methodology.

    Science.gov (United States)

    Santoro, Stefano; Kalek, Marcin; Huang, Genping; Himo, Fahmi

    2016-05-17

    Quantum chemical techniques today are indispensable for the detailed mechanistic understanding of catalytic reactions. The development of modern density functional theory approaches combined with the enormous growth in computer power have made it possible to treat quite large systems at a reasonable level of accuracy. Accordingly, quantum chemistry has been applied extensively to a wide variety of catalytic systems. A huge number of problems have been solved successfully, and vast amounts of chemical insights have been gained. In this Account, we summarize some of our recent work in this field. A number of examples concerned with transition metal-catalyzed reactions are selected, with emphasis on reactions with various kinds of selectivities. The discussed cases are (1) copper-catalyzed C-H bond amidation of indoles, (2) iridium-catalyzed C(sp(3))-H borylation of chlorosilanes, (3) vanadium-catalyzed Meyer-Schuster rearrangement and its combination with aldol- and Mannich-type additions, (4) palladium-catalyzed propargylic substitution with phosphorus nucleophiles, (5) rhodium-catalyzed 1:2 coupling of aldehydes and allenes, and finally (6) copper-catalyzed coupling of nitrones and alkynes to produce β-lactams (Kinugasa reaction). First, the methodology adopted in these studies is presented briefly. The electronic structure method in the great majority of these kinds of mechanistic investigations has for the last two decades been based on density functional theory. In the cases discussed here, mainly the B3LYP functional has been employed in conjunction with Grimme's empirical dispersion correction, which has been shown to improve the calculated energies significantly. The effect of the surrounding solvent is described by implicit solvation techniques, and the thermochemical corrections are included using the rigid-rotor harmonic oscillator approximation. The reviewed examples are chosen to illustrate the usefulness and versatility of the adopted methodology in

  18. Quantum Chemical Studies of Actinides and Lanthanides: From Small Molecules to Nanoclusters

    Science.gov (United States)

    Vlaisavljevich, Bess

    Research into actinides is of high interest because of their potential applications as an energy source and for the environmental implications therein. Global concern has arisen since the development of the actinide concept in the 1940s led to the industrial scale use of the commercial nuclear energy cycle and nuclear weapons production. Large quantities of waste have been generated from these processes inspiring efforts to address fundamental questions in actinide science. In this regard, the objective of this work is to use theory to provide insight and predictions into actinide chemistry, where experimental work is extremely challenging because of the intrinsic difficulties of the experiments themselves and the safety issues associated with this type of chemistry. This thesis is a collection of theoretical studies of actinide chemistry falling into three categories: quantum chemical and matrix isolation studies of small molecules, the electronic structure of organoactinide systems, and uranyl peroxide nanoclusters and other solid state actinide compounds. The work herein not only spans a wide range of systems size but also investigates a range of chemical problems. Various quantum chemical approaches have been employed. Wave function-based methods have been used to study the electronic structure of actinide containing molecules of small to middle-size. Among these methods, the complete active space self consistent field (CASSCF) approach with corrections from second-order perturbation theory (CASPT2), the generalized active space SCF (GASSCF) approach, and Moller-Plesset second-order perturbation theory (MP2) have been employed. Likewise, density functional theory (DFT) has been used along with analysis tools like bond energy decomposition, bond orders, and Bader's Atoms in Molecules. From these quantum chemical results, comparison with experimentally obtained structures and spectra are made.

  19. Quantum chemical density functional theory studies on the molecular structure and vibrational spectra of Gallic acid imprinted polymers

    Science.gov (United States)

    Pardeshi, Sushma; Dhodapkar, Rita; Kumar, Anupama

    2013-12-01

    Gallic acid (GA) is known by its antioxidant, anticarcinogenic properties and scavenger activity against several types of harmful free radicals. Molecularly imprinted polymers (MIPs) are used in separation of a pure compound from complex matrices. A stable template-monomer complex generates the MIPs with the highest affinity and selectivity for the template. The quantum chemical computations based on density functional theory (DFT) was used on the template Gallic acid (GA), monomer acrylic acid (AA) and GA-AA complex to study the nature of interactions involved in the GA-AA complex. B3LYP/6-31+G(2d,2p) model chemistry was used to optimize their structures and frequency calculations. The effect of porogen acetonitrile (ACN) on complex formation was included by using polarizable continuum model (PCM). The results demonstrated the formation of a stable GA-AA complex through the intermolecular hydrogen bonding between carboxylic acid groups of GA and AA. The Mulliken atomic charge analysis and simulated vibrational spectra also supported the stable hydrogen bonding interaction between the carboxylic acid groups of GA and AA with minimal interference of porogen ACN. Further, simulations on GA-AA mole ratio revealed that 1:4 GA-AA was optimum for synthesis of MIP for GA.

  20. Some approaches to the quantum-chemical theory of heterogeneous catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhidomirov, G M

    1977-09-01

    A discussion of mathematical methods, models, and parameters used in various quantum-chemical descriptions of chemisorption and reaction at silica and aluminosilicate surfaces covers the continuous-surface model, the cluster model of the surface, the variation of pseudo-atom parameters to reduce the magnitude of boundary effects in the cluster model, the calculation of individual bond strengths in chemisorbed molecules, dissociative adsorption, applications to adsorption on silica and aluminosilicates, the mechanisms of hydrogen-deuterium exchange, etc. Diagrams, graphs, and 42 references.

  1. Compensation effects in molecular interactions and the quantum chemical le Chatelier principle.

    Science.gov (United States)

    Mezey, Paul G

    2015-05-28

    Components of molecular interactions and various changes in the components of total energy changes during molecular processes typically exhibit some degrees of compensation. This may be as prominent as the over 90% compensation of the electronic energy and nuclear repulsion energy components of the total energy in some conformational changes. Some of these compensations are enhanced by solvent effects. For various arrangements of ions in a solvent, however, not only compensation but also a formal, mutual enhancement between the electronic energy and nuclear repulsion energy components of the total energy may also occur, when the tools of nuclear charge variation are applied to establish quantum chemically rigorous energy inequalities.

  2. On the origin of the gauche effect. A quantum chemical study of 1,2-difluoroethane

    Science.gov (United States)

    Engkvist, O.; Karlström, G.; Widmark, P.-O.

    1997-01-01

    The conformational equilibrium of 1,2-difluoroethane has been investigated using ab initio quantum chemical calculations at the SCF, MP2 and CCSD(T) levels, with ANO basis sets. The relative stability of the gauche-conformation of 1,2-difluoroethane is found to be a consequence of the nodal structure of the singly occupied orbital in the CFH 2 radical. It is also shown that the nodal structure of the singly occupied orbitals in the CFH biradical can explain the stability of the cis conformation of 1,2-difluoroethene.

  3. Evaluation of quantum-chemical methods of radiolysis stability for macromolecular structures

    International Nuclear Information System (INIS)

    Postolache, Cristian; Matei, Lidia

    2005-01-01

    The behavior of macromolecular structures in ionising fields was analyzed by quantum-chemical methods. In this study the primary radiolytic effect was analyzed using a two-step radiolytic mechanism: a) ionisation of molecule and spatial redistribution of atoms in order to reach a minimum value of energy, characteristic to the quantum state; b) neutralisation of the molecule by electron capture and its rapid dissociation into free radicals. Chemical bonds suspected to break are located in the distribution region of LUMO orbital and have minimal homolytic dissociation energies. Representative polymer structures (polyethylene, polypropylene, polystyrene, poly α and β polystyrene, polyisobutylene, polytetrafluoroethylene, poly methylsiloxanes) were analyzed. (authors)

  4. Ab initio quantum chemical calculation as a tool of evaluating diamagnetic susceptibility of magnetically levitating substances

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Y [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Tanimoto, Y [Faculty of Pharmacy, Osaka Ohtani University, Nishikiorikita, Tondabayashi 584-8540 (Japan)], E-mail: fuji0710@sci.hiroshima-u.ac.jp

    2009-03-01

    On magnetic force evaluation necessary for magnetically levitated diamagnetic substances, isotropic diamagnetic susceptibility estimation by the ab initio quantum chemical calculation using Gaussian03W was verified for more than 300 molecules in a viewpoint of the accuracy in the absolute value and the calculation level affording good cost performance. From comparison, the method of B3PW91 / 6-311+G(d,p) was found to give the adequate absolute value by the relation of (observed) = (1.03 {+-} 0.005) x (calculated) - (1.22 {+-} 0.60) x 10{sup -6} in a unit of cm{sup 3} mol{sup -1} and good cost performance.

  5. Ab initio quantum chemical calculation as a tool of evaluating diamagnetic susceptibility of magnetically levitating substances

    International Nuclear Information System (INIS)

    Fujiwara, Y; Tanimoto, Y

    2009-01-01

    On magnetic force evaluation necessary for magnetically levitated diamagnetic substances, isotropic diamagnetic susceptibility estimation by the ab initio quantum chemical calculation using Gaussian03W was verified for more than 300 molecules in a viewpoint of the accuracy in the absolute value and the calculation level affording good cost performance. From comparison, the method of B3PW91 / 6-311+G(d,p) was found to give the adequate absolute value by the relation of (observed) = (1.03 ± 0.005) x (calculated) - (1.22 ± 0.60) x 10 -6 in a unit of cm 3 mol -1 and good cost performance.

  6. ELECTROREDUCTION MECHANISM OF Ni(DMG)-2 COMPLEX STUDIED WITH QUANTUM CHEMICAL METHOD

    Institute of Scientific and Technical Information of China (English)

    倪亚明; 任镜清; 黎健; 王德民; 梁伟根; 朱芝仙; 高小霞

    1990-01-01

    The electronic structures of the species Ni(DMG)2, (Ni(DMG)2)- and (Ni(DMG)2)2- have been studied by INDO quantum chemical method. The results have clearly shown that in the first stage of the electroreduction of Ni(DMG)2, one electron interacts with the d orbitals on the nickel atom, while in the further stage the second electron interacts with the p orbitals on the nitrogen atoms. It conforms with our electrochemical experimental studies which showed that not only Ni(Ⅱ) is reduced but also DMG is catalytically reduced during the reduction of Ni(DMG)2.

  7. Quantum Chemical Prediction of Equilibrium Acidities of Ureas, Deltamides, Squaramides, and Croconamides.

    Science.gov (United States)

    Ho, Junming; Zwicker, Vincent E; Yuen, Karen K Y; Jolliffe, Katrina A

    2017-10-06

    Robust quantum chemical methods are employed to predict the pK a 's of several families of dual hydrogen-bonding organocatalysts/anion receptors, including deltamides and croconamides as well as their thio derivatives. The average accuracy of these predictions is ∼1 pK a unit and allows for a comparison of the acidity between classes of receptors and for quantitative studies of substituent effects. These computational insights further explain the relationship between pK a and chloride anion affinity of these receptors that will be important for designing future anion receptors and organocatalysts.

  8. Intra- und intermolecular hydrogen bonds. Spectroscopic, quantum chemical and molecular dynamics studies

    International Nuclear Information System (INIS)

    Simperler, A.

    1999-03-01

    Intra- and intermolecular H-bonds have been investigated with spectroscopic, quantum chemical, and molecular dynamics methods. The work is divided into the following three parts: 1. Intramolecular interactions in ortho-substituted phenols. Theoretical and experimental data that characterizes the intramolecular hydrogen bonds in 48 different o-substituted phenols are discussed. The study covers various kinds of O-H ... Y -type interactions (Y= N, O, S, F, Cl, Br, I, C=C, C=-C, and C-=N). The bond strength sequences for several series of systematically related compounds as obtained from IR spectroscopy data (i.e., v(OH) stretching frequencies) are discussed and reproduced with several theoretical methods (B3LYP/6-31G(d,p), B3LYP/6-311G(d,p), B3LYP/6-31++G(d,p), B3LYP/DZVP, MP2/6-31G(d,p), and MP2/6-31++G(d,p) levels of theory). The experimentally determined sequences are interpreted in terms of the intrinsic properties of the molecules: hydrogen bond distances, Mulliken partial charges, van der Waals radii, and electron densities of the Y-proton acceptors. 2. Competitive hydrogen bonds and conformational equilibria in 2,6-disubstituted phenols containing two different carbonyl substituents. The rotational isomers of ten unsymmetrical 2,6-disubstituted phenols as obtained by combinations of five different carbonyl substituents (COOH, COOCH 3 , CHO, COCH 3 , and CONH 2 ) have been theoretically investigated at the B3LYP/6-31G(d,p) level of theory. The relative stability of four to five conformers of each compound were determined by full geometry optimization for free molecules as well as for molecules in reaction fields with dielectric constants up to ε=37.5. A comparison with IR spectroscopic data of available compounds revealed excellent agreement with the theoretically predicted stability sequences and conformational equilibria. The stability of a conformer could be interpreted to be governed by the following two contributions: (i) an attractive hydrogen bond

  9. Mechanism of Microwave-Assisted Pyrolysis of Glucose to Furfural Revealed by Isotopic Tracer and Quantum Chemical Calculations.

    Science.gov (United States)

    Bao, Liwei; Shi, Lei; Luo, Hu; Kong, Lingzhao; Li, Shenggang; Wei, Wei; Sun, Yuhan

    2017-08-10

    Glucose labeled with 13 C or 18 O was used to investigate the mechanism of its conversion into furfural by microwaveassisted pyrolysis. The isotopic content and location in furfural were determined from GC-MS and 13 C NMR spectroscopic measurements and data analysis. The results suggest that the carbon skeleton in furfural is mainly derived from C1 to C5 of glucose, whereas the C of the aldehyde group and the O of the furan ring in furfural primarily originate from C1 and O5 of glucose, respectively. For the first time, the source of O in the furan ring of furfural was elucidated directly by experiment, providing results that are consistent with predictions from recent quantum chemical calculations. Moreover, further theoretical calculations indicate substantially lower energy barriers than previous predictions by considering the potential catalytic effect of formic acid, which is one of the pyrolysis products. The catalytic role of formic acid is further confirmed by experimental evidence. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. X-ray diffraction, vibrational and quantum chemical investigations of 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid

    Science.gov (United States)

    Arjunan, V.; Marchewka, Mariusz K.; Pietraszko, A.; Kalaivani, M.

    2012-11-01

    The structural investigations of the molecular complex of 2-methyl-4-nitroaniline with trichloroacetic acid, namely 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid (C11H10Cl6N2O6) have been performed by means of single crystal and powder X-ray diffraction method. The complex was formed with accompanying proton transfer from trichloroacetic acid molecule to 2-methyl-4-nitroaniline. The studied crystal is built up of singly protonated 2-methyl-4-nitroanilinium cations, trichloroacetate anions and neutral trichloroacetic acid molecules. The crystals are monoclinic, space group P21/c, with a = 14.947 Å, b = 6.432 Å, c = 19.609 Å and Z = 4. The vibrational assignments and analysis of 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid have also been performed by FTIR, FT-Raman and far-infrared spectral studies. More support on the experimental findings were added from the quantum chemical studies performed with DFT (B3LYP) method using 6-31G**, cc-pVDZ, 6-31G and 6-31++G basis sets. The structural parameters, energies, thermodynamic parameters and the NBO charges of 2M4NATCA were also determined by the DFT methods.

  11. Structure, vibrations and quantum chemical investigations of hydrogen bonded complex of bis(1-hydroxy-2-methylpropan-2-aminium)selenate

    Science.gov (United States)

    Thirunarayanan, S.; Arjunan, V.; Marchewka, M. K.; Mohan, S.

    2017-04-01

    The hydrogen bonded molecular complex bis(1-hydroxy-2-methylpropan-2-aminium)selenate (C8H24N2O6Se) has been prepared by the reaction of 2-amino-2-methyl propanol and selenic acid. The X-ray diffraction analysis revealed that the intermolecular proton transfer from selenic acid (SeO4H2) to 2-amino-2-methylpropanol results in the formation of bis(1-hydroxy-2-methylpropan-2-aminium)selenate (HMPAS) salt and the fragments are connected through H-bonding and ion pairing. The N-H⋯O and O-H⋯O interactions between 2-amino-2-methylpropanol and selenic acid determine the supramolecular arrangement in three-dimensional space. The salt crystallises in the space group P121/n1 of monoclinic system. The complete vibrational assignments of HMPAS have been performed by FTIR and FT-Raman spectroscopy. The experimental data are correlated with the structural properties namely the energy, thermodynamic parameters, atomic charges, hybridization concepts and vibrational frequencies determined by quantum chemical studies performed with B3LYP method using 6-311++G*, 6-31+G* and 6-31G** basis sets.

  12. Include dispersion in quantum chemical modeling of enzymatic reactions: the case of isoaspartyl dipeptidase.

    Science.gov (United States)

    Zhang, Hai-Mei; Chen, Shi-Lu

    2015-06-09

    The lack of dispersion in the B3LYP functional has been proposed to be the main origin of big errors in quantum chemical modeling of a few enzymes and transition metal complexes. In this work, the essential dispersion effects that affect quantum chemical modeling are investigated. With binuclear zinc isoaspartyl dipeptidase (IAD) as an example, dispersion is included in the modeling of enzymatic reactions by two different procedures, i.e., (i) geometry optimizations followed by single-point calculations of dispersion (approach I) and (ii) the inclusion of dispersion throughout geometry optimization and energy evaluation (approach II). Based on a 169-atom chemical model, the calculations show a qualitative consistency between approaches I and II in energetics and most key geometries, demonstrating that both approaches are available with the latter preferential since both geometry and energy are dispersion-corrected in approach II. When a smaller model without Arg233 (147 atoms) was used, an inconsistency was observed, indicating that the missing dispersion interactions are essentially responsible for determining equilibrium geometries. Other technical issues and mechanistic characteristics of IAD are also discussed, in particular with respect to the effects of Arg233.

  13. Quantum chemical molecular dynamical investigation of alkyl nitrite photo-dissociated on copper surfaces

    International Nuclear Information System (INIS)

    Wang Xiaojing; Wang Wei; Han Peilin; Kubo, Momoji; Miyamoto, Akira

    2008-01-01

    An accelerated quantum chemical molecular dynamical code 'Colors-Excite' was used to investigate the photolysis of alkyl nitrites series, RONO (R=CH 3 and C(CH 3 ) 3 ) on copper surfaces. Our calculations showed that the photo-dissociated processes are associated with the alkyl substituents of RONO when adsorbed on copper surfaces. For R=CH 3 , a two-step photolysis reaction occurred, yielding diverse intermediate products including RO radical, NO, and HNO, consistent with those reported in gas phase. While for R=C(CH 3 ) 3 , only one-step photolysis reaction occurred and gave intermediate products of RO radical and NO. Consequently, pure RO species were achieved to adsorb on metal surfaces by removing the NO species in photolysis reaction. The detailed photo-dissociated behaviors of RONO on copper surfaces with different alkyl substituents which are uncovered by the present simulation can be extended to explain the diverse dissociative mechanism experimentally observed. The quantum chemical molecular dynamical code 'Colors-Excite' is proved to be highly applicable to the photo-dissociations on metal surfaces

  14. TG-FTIR, DSC and quantum chemical studies of the thermal decomposition of quaternary methylammonium halides

    International Nuclear Information System (INIS)

    Sawicka, Marlena; Storoniak, Piotr; Skurski, Piotr; Blazejowski, Jerzy; Rak, Janusz

    2006-01-01

    The thermal decomposition of quaternary methylammonium halides was studied using thermogravimetry coupled to FTIR (TG-FTIR) and differential scanning calorimetry (DSC) as well as the DFT, MP2 and G2 quantum chemical methods. There is almost perfect agreement between the experimental IR spectra and those predicted at the B3LYP/6-311G(d,p) level: this has demonstrated for the first time that an equimolar mixture of trimethylamine and a methyl halide is produced as a result of decomposition. The experimental enthalpies of dissociation are 153.4, 171.2, and 186.7 kJ/mol for chloride, bromide and iodide, respectively, values that correlate well with the calculated enthalpies of dissociation based on crystal lattice energies and quantum chemical thermodynamic barriers. The experimental activation barriers estimated from the least-squares fit of the F1 kinetic model (first-order process) to thermogravimetric traces - 283, 244 and 204 kJ/mol for chloride, bromide and iodide, respectively - agree very well with theoretically calculated values. The theoretical approach assumed in this work has been shown capable of predicting the relevant characteristics of the thermal decomposition of solids with experimental accuracy

  15. New Insights into the genetic diversity of Clostridium botulinum Group III through extensive genome exploration

    Directory of Open Access Journals (Sweden)

    Cédric eWoudstra

    2016-05-01

    Full Text Available Animal botulism is caused by group III Clostridium botulinum strains producing type C and D toxins, or their chimeric forms C/D and D/C. Animal botulism is considered an emerging disease in Europe, notably in poultry production. Before our study, 14 genomes from different countries were available in the public database, but none were from France. In order to investigate the genetic relationship of French strains with different geographical areas and find new potential typing targets, 17 strains of C. botulinum group III were sequenced (16 from France and one from New Caledonia. Fourteen were type C/D strains isolated from chickens, ducks, guinea fowl and turkeys and three were type D/C strains isolated from cattle. The New Caledonian strain was a type D/C strain. Whole genome sequence analysis showed the French strains to be closely related to European strains from C. botulinum group III lineages Ia and Ib. The investigation of CRISPR sequences as genetic targets for differentiating strains in group III proved to be irrelevant for type C/D due to a deficient CRISPR/Cas mechanism, but not for type D/C. Conversely, the extrachromosomal elements of type C/D strains could be used to generate a genetic ID card. The highest level of discrimination was achieved with SNP core phylogeny, which allowed differentiation up to strain level and provide the most relevant information for genetic epidemiology studies and discrimination.

  16. Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

    Science.gov (United States)

    Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

    2016-05-15

    Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Degradation of Perfluorinated Ether Lubricants on Pure Aluminum Surfaces: Semiempirical Quantum Chemical Modeling

    Science.gov (United States)

    Slaby, Scott M.; Ewing, David W.; Zehe, Michael J.

    1997-01-01

    The AM1 semiempirical quantum chemical method was used to model the interaction of perfluoroethers with aluminum surfaces. Perfluorodimethoxymethane and perfluorodimethyl ether were studied interacting with aluminum surfaces, which were modeled by a five-atom cluster and a nine-atom cluster. Interactions were studied for edge (high index) sites and top (low index) sites of the clusters. Both dissociative binding and nondissociative binding were found, with dissociative binding being stronger. The two different ethers bound and dissociated on the clusters in different ways: perfluorodimethoxymethane through its oxygen atoms, but perfluorodimethyl ether through its fluorine atoms. The acetal linkage of perfluorodimeth-oxymethane was the key structural feature of this molecule in its binding and dissociation on the aluminum surface models. The high-index sites of the clusters caused the dissociation of both ethers. These results are consistent with the experimental observation that perfluorinated ethers decompose in contact with sputtered aluminum surfaces.

  18. QSAR analysis of salicylamide isosteres with the use of quantum chemical molecular descriptors.

    Science.gov (United States)

    Dolezal, R; Van Damme, S; Bultinck, P; Waisser, K

    2009-02-01

    Quantitative relationships between the molecular structure and the biological activity of 49 isosteric salicylamide derivatives as potential antituberculotics with a new mechanism of action against three Mycobacterial strains were investigated. The molecular structures were represented by quantum chemical B3LYP/6-31G( *) based molecular descriptors. A resulting set of 220 molecular descriptors, including especially electronic properties, was statistically analyzed using multiple linear regression, resulting in acceptable and robust QSAR models. The best QSAR model was found for Mycobacterium tuberculosis (r(2)=0.92; q(2)=0.89), and somewhat less good QSAR models were found for Mycobacterium avium (r(2)=0.84; q(2)=0.78) and Mycobacterium kansasii (r(2)=0.80; q(2)=0.56). All QSAR models were cross-validated using the leave-10-out procedure.

  19. Quantum chemical simulation of hydrogen like states in silicon and diamond

    International Nuclear Information System (INIS)

    Gel'fand, R.B.; Gordeev, V.A.; Gorelkinskij, Yu.V.

    1989-01-01

    The quantum-chemical methods of the complete neglect of differential overlap (CNDO) and intermediate neglect of differential overlap (INDO) are used to calculate the electronic structure of atomic hydrogen (muonium) located at different interstital sites of the silicon and diamond crystal lattices. The electronic g- and hyperfine interaction tensors of the impure atom are determined.The results obtained are compared with the experimental data on the 'normal' (Mu') and 'anomalous' (Mu * ) muonium centers as well as on the hydrogen-bearing Si-AA9 EPR center which is a hydrogen-bearing analogue of (Mu * ). The most likely localization sites for hydrogen (muonium) atoms in silicon and diamond crystals are established. 22 refs

  20. Random Forest Approach to QSPR Study of Fluorescence Properties Combining Quantum Chemical Descriptors and Solvent Conditions.

    Science.gov (United States)

    Chen, Chia-Hsiu; Tanaka, Kenichi; Funatsu, Kimito

    2018-04-22

    The Quantitative Structure - Property Relationship (QSPR) approach was performed to study the fluorescence absorption wavelengths and emission wavelengths of 413 fluorescent dyes in different solvent conditions. The dyes included the chromophore derivatives of cyanine, xanthene, coumarin, pyrene, naphthalene, anthracene and etc., with the wavelength ranging from 250 nm to 800 nm. An ensemble method, random forest (RF), was employed to construct nonlinear prediction models compared with the results of linear partial least squares and nonlinear support vector machine regression models. Quantum chemical descriptors derived from density functional theory method and solvent information were also used by constructing models. The best prediction results were obtained from RF model, with the squared correlation coefficients [Formula: see text] of 0.940 and 0.905 for λ abs and λ em , respectively. The descriptors used in the models were discussed in detail in this report by comparing the feature importance of RF.

  1. Quantum chemical modeling of the inhibition mechanism of monoamine oxidase by oxazolidinone and analogous heterocyclic compounds.

    Science.gov (United States)

    Erdem, Safiye Sağ; Özpınar, Gül Altınbaş; Boz, Ümüt

    2014-02-01

    Monoamine oxidase (MAO, EC 1.4.3.4) is responsible from the oxidation of a variety of amine neurotransmitters. MAO inhibitors are used for the treatment of depression or Parkinson's disease. They also inhibit the catabolism of dietary amines. According to one hypothesis, inactivation results from the formation of a covalent adduct to a cysteine residue in the enzyme. If the adduct is stable enough, the enzyme is inhibited for a long time. After a while, enzyme can turn to its active form as a result of adduct breakdown by β-elimination. In this study, the proposed inactivation mechanism was modeled and tested by quantum chemical calculations. Eight heterocyclic methylthioamine derivatives were selected to represent the proposed covalent adducts. Activation energies related to their β-elimination reactions were calculated using ab initio and density functional theory methods. Calculated activation energies were in good agreement with the relative stabilities of the hypothetical adducts predicted in the literature by enzyme inactivation measurements.

  2. Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations

    Science.gov (United States)

    Karthick, N. K.; Kumbharkhane, A. C.; Joshi, Y. S.; Mahendraprabu, A.; Shanmugam, R.; Elangovan, A.; Arivazhagan, G.

    2017-05-01

    Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) Csbnd H ⋯ Odbnd C (EA), (EA) methylene Csbnd H ⋯ π electrons (CBZ) and (EA) methyl Csbnd H ⋯ Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (εE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

  3. Semiempirical Quantum Chemical Calculations Accelerated on a Hybrid Multicore CPU-GPU Computing Platform.

    Science.gov (United States)

    Wu, Xin; Koslowski, Axel; Thiel, Walter

    2012-07-10

    In this work, we demonstrate that semiempirical quantum chemical calculations can be accelerated significantly by leveraging the graphics processing unit (GPU) as a coprocessor on a hybrid multicore CPU-GPU computing platform. Semiempirical calculations using the MNDO, AM1, PM3, OM1, OM2, and OM3 model Hamiltonians were systematically profiled for three types of test systems (fullerenes, water clusters, and solvated crambin) to identify the most time-consuming sections of the code. The corresponding routines were ported to the GPU and optimized employing both existing library functions and a GPU kernel that carries out a sequence of noniterative Jacobi transformations during pseudodiagonalization. The overall computation times for single-point energy calculations and geometry optimizations of large molecules were reduced by one order of magnitude for all methods, as compared to runs on a single CPU core.

  4. A theoretical quantum chemical study of alanine formation in interstellar medium

    Science.gov (United States)

    Shivani; Pandey, Parmanad; Misra, Alka; Tandon, Poonam

    2017-08-01

    The interstellar medium, the vast space between the stars, is a rich reservoir of molecular material ranging from simple diatomic molecules to more complex, astrobiologically important molecules such as amino acids, nucleobases, and other organic species. Radical-radical and radical-neutral interaction schemes are very important for the formation of comparatively complex molecules in low temperature chemistry. An attempt has been made to explore the possibility of formation of complex organic molecules in interstellar medium, through detected interstellar molecules like CH3CN and HCOOH. The gas phase reactions are theoretically studied using quantum chemical techniques. We used the density functional theory (DFT) at the B3LYP/6-311G( d, p) level. The reaction energies, potential barrier and optimized structures of all the geometries, involved in the reaction path, has been discussed. We report the potential energy surfaces for the reactions considered in this work.

  5. Vibrational, electronic and quantum chemical studies of 1,2,4-benzenetricarboxylic-1,2-anhydride.

    Science.gov (United States)

    Arjunan, V; Raj, Arushma; Subramanian, S; Mohan, S

    2013-06-01

    The FTIR and FT-Raman spectra of 1,2,4-benzenetricarboxylic-1,2-anhydride (BTCA) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The complete vibrational assignments and analysis of BTCA have been performed. More support on the experimental findings was added from the quantum chemical studies performed with DFT (B3LYP, MP2, B3PW91) method using 6-311++G(**), 6-31G(**) and cc-pVTZ basis sets. The structural parameters, energies, thermodynamic parameters, vibrational frequencies and the NBO charges of BTCA were determined by the DFT method. The (1)H and (13)C isotropic chemical shifts (δ ppm) of BTCA with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. The delocalization energies of different types of interactions were determined. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Prediction of monomer reactivity in radical copolymerizations from transition state quantum chemical descriptors

    Directory of Open Access Journals (Sweden)

    Zhengde Tan

    2013-01-01

    Full Text Available In comparison with the Q-e scheme, the Revised Patterns Scheme: the U, V Version (the U-V scheme has greatly improved both its accessibility and its accuracy in interpreting and predicting the reactivity of a monomer in free-radical copolymerizations. Quantitative structure-activity relationship (QSAR models were developed to predict the reactivity parameters u and v of the U-V scheme, by applying genetic algorithm (GA and support vector machine (SVM techniques. Quantum chemical descriptors used for QSAR models were calculated from transition state species with structures C¹H3 - C²HR³• or •C¹H2 - C²H2R³ (formed from vinyl monomers C¹H²=C²HR³ + H•, using density functional theory (DFT, at the UB3LYP level of theory with 6-31G(d basis set. The optimum support vector regression (SVR model of the reactivity parameter u based on Gaussian radial basis function (RBF kernel (C = 10, ε = 10- 5 and γ = 1.0 produced root-mean-square (rms errors for the training, validation and prediction sets being 0.220, 0.326 and 0.345, respectively. The optimal SVR model for v with the RBF kernel (C = 20, ε = 10- 4 and γ = 1.2 produced rms errors for the training set of 0.123, the validation set of 0.206 and the prediction set of 0.238. The feasibility of applying the transition state quantum chemical descriptors to develop SVM models for reactivity parameters u and v in the U-V scheme has been demonstrated.

  7. Proton exchange between oxymethyl radical and acids and bases: semiempirical quantum-chemical study

    Directory of Open Access Journals (Sweden)

    Irina Pustolaikina

    2016-12-01

    Full Text Available The reactions with proton participation are widely represented in the analytical, technological and biological chemistry. Quantum-chemical study of the exchange processes in hydrogen bonding complexes will allow us to achieve progress in the understanding of the elementary act mechanism of proton transfer in hydrogen bonding chain as well as the essence of the acid-base interactions. Oxymethyl radical •CH2ОН is small in size and comfortable as a model particle that well transmits protolytic properties of paramagnetic acids having more complex structure. Quantum-chemical modeling of proton exchange reaction oxymethyl radical ∙CH2OH and its diamagnetic analog CH3OH with amines, carboxylic acids and water was carried out using UAM1 method with the help of Gaussian-2009 program. QST2 method was used for the search of transition state, IRC procedure was applied for the calculation of descents along the reaction coordinate. The difference in the structure of transition states of ∙CH2OH/ CH3OH with bases and acids has been shown. It has been confirmed that in the case of bases, consecutive proton exchange mechanism was fixed, and in the case of complexes with carboxylic acids parallel proton exchange mechanism was fixed. The similarity in the reaction behavior of paramagnetic and diamagnetic systems in the proton exchange has been found. It was suggested that the mechanism of proton exchange reaction is determined by the structure of the hydrogen bonding cyclic complex, which is, in turn, depends from the nature of the acid-base interactions partners.

  8. Development of a quantum chemical molecular dynamics tribochemical simulator and its application to tribochemical reaction dynamics of lubricant additives

    International Nuclear Information System (INIS)

    Onodera, T; Tsuboi, H; Hatakeyama, N; Endou, A; Miyamoto, A; Miura, R; Takaba, H; Suzuki, A; Kubo, M

    2010-01-01

    Tribology at the atomistic and molecular levels has been theoretically studied by a classical molecular dynamics (MD) method. However, this method inherently cannot simulate the tribochemical reaction dynamics because it does not consider the electrons in nature. Although the first-principles based MD method has recently been used for understanding the chemical reaction dynamics of several molecules in the tribology field, the method cannot simulate the tribochemical reaction dynamics of a large complex system including solid surfaces and interfaces due to its huge computation costs. On the other hand, we have developed a quantum chemical MD tribochemical simulator on the basis of a hybrid tight-binding quantum chemical/classical MD method. In the simulator, the central part of the chemical reaction dynamics is calculated by the tight-binding quantum chemical MD method, and the remaining part is calculated by the classical MD method. Therefore, the developed tribochemical simulator realizes the study on tribochemical reaction dynamics of a large complex system, which cannot be treated by using the conventional classical MD or the first-principles MD methods. In this paper, we review our developed quantum chemical MD tribochemical simulator and its application to the tribochemical reaction dynamics of a few lubricant additives

  9. Quantum-chemical calculations and electron diffraction study of the equilibrium molecular structure of vitamin K3

    Science.gov (United States)

    Khaikin, L. S.; Tikhonov, D. S.; Grikina, O. E.; Rykov, A. N.; Stepanov, N. F.

    2014-05-01

    The equilibrium molecular structure of 2-methyl-1,4-naphthoquinone (vitamin K3) having C s symmetry is experimentally characterized for the first time by means of gas-phase electron diffraction using quantum-chemical calculations and data on the vibrational spectra of related compounds.

  10. Quantum-Chemical Electron Densities of Proteins and of Selected Protein Sites from Subsystem Density Functional Theory

    NARCIS (Netherlands)

    Kiewisch, K.; Jacob, C.R.; Visscher, L.

    2013-01-01

    The ability to calculate accurate electron densities of full proteins or of selected sites in proteins is a prerequisite for a fully quantum-mechanical calculation of protein-protein and protein-ligand interaction energies. Quantum-chemical subsystem methods capable of treating proteins and other

  11. Effects of a group-based reproductive management extension programme on key management outcomes affecting reproductive performance.

    Science.gov (United States)

    Brownlie, Tom S; Morton, John M; Heuer, Cord; McDougall, Scott

    2015-02-01

    A group-based reproductive management extension programme has been designed to help managers of dairy herds improve herd reproductive performance. The aims of this study were, firstly, to assess effects of participation by key decision makers (KDMs) in a farmer action group programme in 2009 and 2010 on six key management outcomes (KMOs) that affect reproductive performance over 2 years (2009-2010 and 2010-2011), and secondly, to describe KDM intentions to change management behaviour(s) affecting each management outcome after participation in the programme. Seasonal calving dairy herds from four regions of New Zealand were enrolled in the study. Intentions to modify management behaviour were recorded using the formal written action plans developed during the extension programme. KMOs assessed were calving pattern of the herd, pre-calving heifer liveweight, pre-calving and premating body condition score (BCS), oestrus detection, anoestrus cow management and bull management. Participation was associated with improvements in heifer liveweight, more heifers calving in the first 6 weeks of the seasonal calving period, premating BCS and oestrus detection. No significant effects were observed on anoestrus cow management or bull management. KDMs with greater numbers of proposed actions had lower 6 week in-calf rates in the second study year than KDMs who proposed fewer actions. A more effective strategy to ensure more appropriate objectives is proposed. Strategies to help KDMs to implement proposed actions more successfully should be investigated to improve the programme further. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Molecular structure of tris(cyclopropylsilyl)amine as determined by gas electron diffraction and quantum-chemical calculations

    Science.gov (United States)

    Vishnevskiy, Yuri V.; Abaev, Maxim A.; Ivanov, Arkadii A.; Vilkov, Lev V.; Dakkouri, Marwan

    2008-10-01

    The molecular structure and conformation of tris(cyclopropylsilyl)amine (TCPSA) has been studied by means of gas-phase electron diffraction at 338 K and quantum-chemical calculations. A total of 12 relatively stable conformations of TCPSA molecule were considered. According to the experimental results and the DFT calculations the most stable conformer corresponds to a configuration (according to the Prelog-Klyne notation) of the type (-ac)(-ac)(+ac)-(-ac)(-ac)(+ac), where the first three parentheses describe the three different Si-N-Si-C torsional angles and the latter ones depict the rotation of the three cyclopropyl groups about the C ring-Si axes, respectively. The quantum-mechanical calculations were performed using various density functional (B3LYP, X3LYP and O3LYP) and perturbation MP2 methods in combination with double- and triple- ζ basis sets plus polarization and diffuse functions. The most important experimental geometrical parameters of TCPSA ( ra Å, ∠ h1 degrees) are: (Si-N) av = 1.741(3), (Si-C) av = 1.866(4), (C-C) av = 1.510(3), (C-C(Si)) av = 1.535(3), (N-Si-C) av = 115.1(18)°. For the purpose of comparison and searching for reasons leading to the planarity of the Si 3N moiety in trisilylated amines we carried out NBO analysis and optimized the geometries of numerous silylamines. Among these compounds was tris(allylsilyl)amine (TASA), which is isovalent and isoelectronic to TCPSA. Utilizing the structural results we obtained we could show that Si +⋯Si + electrostatic repulsive interaction is predominantly responsible for the planarity of the Si 3N skeleton in TCPSA and in all other trisilylamines we considered. We also found that regardless the size and partial charges of the substituents the Si-N-Si bond angle in various disilylamines amounts to 130 ± 2°.

  13. Rotational Spectrum, Conformational Composition, Intramolecular Hydrogen Bonding, and Quantum Chemical Calculations of Mercaptoacetonitrile (HSCH2C≡N), a Compound of Potential Astrochemical Interest.

    Science.gov (United States)

    Møllendal, Harald; Samdal, Svein; Guillemin, Jean-Claude

    2016-03-31

    The microwave spectra of mercaptoacetonitrile (HSCH2C≡N) and one deuterated species (DSCH2C≡N) were investigated in the 7.5-124 GHz spectral interval. The spectra of two conformers denoted SC and AP were assigned. The H-S-C-C chain of atoms is synclinal in SC and anti-periplanar in AP. The ground state of SC is split into two substates separated by a comparatively small energy difference resulting in closely spaced transitions with equal intensities. Several transitions of the parent species of SC deviate from Watson's Hamiltonian. Only slight improvements were obtained using a Hamiltonian that takes coupling between the two substates into account. Deviations from Watson's Hamiltonian were also observed for the parent species of AP. However, the spectrum of the deuterated species, which was investigated only for the SC conformer, fits satisfactorily to Watson's Hamiltonian. Relative intensity measurements found SC to be lower in energy than AP by 3.8(3) kJ/mol. The strength of the intramolecular hydrogen bond between the thiol and cyano groups was estimated to be ∼2.1 kJ/mol. The microwave work was augmented by quantum chemical calculations at CCSD and MP2 levels using basis sets of minimum triple-ζ quality. Mercaptoacetonitrile has astrochemical interest, and the spectra presented herein should be useful for a potential identification of this compound in the interstellar medium. Three different ways of generating mercaptoacetonitrile from compounds already found in the interstellar medium were explored by quantum chemical calculations.

  14. Predicting Hydride Donor Strength via Quantum Chemical Calculations of Hydride Transfer Activation Free Energy.

    Science.gov (United States)

    Alherz, Abdulaziz; Lim, Chern-Hooi; Hynes, James T; Musgrave, Charles B

    2018-01-25

    We propose a method to approximate the kinetic properties of hydride donor species by relating the nucleophilicity (N) of a hydride to the activation free energy ΔG ⧧ of its corresponding hydride transfer reaction. N is a kinetic parameter related to the hydride transfer rate constant that quantifies a nucleophilic hydridic species' tendency to donate. Our method estimates N using quantum chemical calculations to compute ΔG ⧧ for hydride transfers from hydride donors to CO 2 in solution. A linear correlation for each class of hydrides is then established between experimentally determined N values and the computationally predicted ΔG ⧧ ; this relationship can then be used to predict nucleophilicity for different hydride donors within each class. This approach is employed to determine N for four different classes of hydride donors: two organic (carbon-based and benzimidazole-based) and two inorganic (boron and silicon) hydride classes. We argue that silicon and boron hydrides are driven by the formation of the more stable Si-O or B-O bond. In contrast, the carbon-based hydrides considered herein are driven by the stability acquired upon rearomatization, a feature making these species of particular interest, because they both exhibit catalytic behavior and can be recycled.

  15. How to compute isomerization energies of organic molecules with quantum chemical methods.

    Science.gov (United States)

    Grimme, Stefan; Steinmetz, Marc; Korth, Martin

    2007-03-16

    The reaction energies for 34 typical organic isomerizations including oxygen and nitrogen heteroatoms are investigated with modern quantum chemical methods that have the perspective of also being applicable to large systems. The experimental reaction enthalpies are corrected for vibrational and thermal effects, and the thus derived "experimental" reaction energies are compared to corresponding theoretical data. A series of standard AO basis sets in combination with second-order perturbation theory (MP2, SCS-MP2), conventional density functionals (e.g., PBE, TPSS, B3-LYP, MPW1K, BMK), and new perturbative functionals (B2-PLYP, mPW2-PLYP) are tested. In three cases, obvious errors of the experimental values could be detected, and accurate coupled-cluster [CCSD(T)] reference values have been used instead. It is found that only triple-zeta quality AO basis sets provide results close enough to the basis set limit and that sets like the popular 6-31G(d) should be avoided in accurate work. Augmentation of small basis sets with diffuse functions has a notable effect in B3-LYP calculations that is attributed to intramolecular basis set superposition error and covers basic deficiencies of the functional. The new methods based on perturbation theory (SCS-MP2, X2-PLYP) are found to be clearly superior to many other approaches; that is, they provide mean absolute deviations of less than 1.2 kcal mol-1 and only a few (computational thermochemistry methods.

  16. Quantum chemical modeling of zeolite-catalyzed methylation reactions: toward chemical accuracy for barriers.

    Science.gov (United States)

    Svelle, Stian; Tuma, Christian; Rozanska, Xavier; Kerber, Torsten; Sauer, Joachim

    2009-01-21

    The methylation of ethene, propene, and t-2-butene by methanol over the acidic microporous H-ZSM-5 catalyst has been investigated by a range of computational methods. Density functional theory (DFT) with periodic boundary conditions (PBE functional) fails to describe the experimentally determined decrease of apparent energy barriers with the alkene size due to inadequate description of dispersion forces. Adding a damped dispersion term expressed as a parametrized sum over atom pair C(6) contributions leads to uniformly underestimated barriers due to self-interaction errors. A hybrid MP2:DFT scheme is presented that combines MP2 energy calculations on a series of cluster models of increasing size with periodic DFT calculations, which allows extrapolation to the periodic MP2 limit. Additionally, errors caused by the use of finite basis sets, contributions of higher order correlation effects, zero-point vibrational energy, and thermal contributions to the enthalpy were evaluated and added to the "periodic" MP2 estimate. This multistep approach leads to enthalpy barriers at 623 K of 104, 77, and 48 kJ/mol for ethene, propene, and t-2-butene, respectively, which deviate from the experimentally measured values by 0, +13, and +8 kJ/mol. Hence, enthalpy barriers can be calculated with near chemical accuracy, which constitutes significant progress in the quantum chemical modeling of reactions in heterogeneous catalysis in general and microporous zeolites in particular.

  17. Quantum chemical modeling of enzymatic reactions: the case of histone lysine methyltransferase.

    Science.gov (United States)

    Georgieva, Polina; Himo, Fahmi

    2010-06-01

    Quantum chemical cluster models of enzyme active sites are today an important and powerful tool in the study of various aspects of enzymatic reactivity. This methodology has been applied to a wide spectrum of reactions and many important mechanistic problems have been solved. Herein, we report a systematic study of the reaction mechanism of the histone lysine methyltransferase (HKMT) SET7/9 enzyme, which catalyzes the methylation of the N-terminal histone tail of the chromatin structure. In this study, HKMT SET7/9 serves as a representative case to examine the modeling approach for the important class of methyl transfer enzymes. Active site models of different sizes are used to evaluate the methodology. In particular, the dependence of the calculated energies on the model size, the influence of the dielectric medium, and the particular choice of the dielectric constant are discussed. In addition, we examine the validity of some technical aspects, such as geometry optimization in solvent or with a large basis set, and the use of different density functional methods. Copyright 2010 Wiley Periodicals, Inc.

  18. Energetics and stability of azulene: From experimental thermochemistry to high-level quantum chemical calculations

    International Nuclear Information System (INIS)

    Sousa, Clara C.S.; Matos, M. Agostinha R.; Morais, Victor M.F.

    2014-01-01

    Highlights: • Experimental standard molar enthalpy of formation, sublimation azulene. • Mini-bomb combustion calorimetry, sublimation Calvet microcalorimetry. • High level composite ab initio calculations. • Computational estimate of the enthalpy of formation of azulene. • Discussion of stability and aromaticity of azulene. - Abstract: The standard (p 0 = 0.1 MPa) molar enthalpy of formation for crystalline azulene was derived from the standard molar enthalpy of combustion, in oxygen, at T = 298.15 K, measured in a mini-bomb combustion calorimeter (aneroid isoperibol calorimeter) and the standard molar enthalpy of sublimation, at T = 298.15 K, measured by Calvet microcalorimetry. From these experiments, the standard molar enthalpy of formation of azulene in the gaseous phase at T = 298.15 K was calculated. In addition, very accurate quantum chemical calculations at the G3 and G4 composite levels of calculation were conducted in order to corroborate our experimental findings and further clarify and establish the definitive standard enthalpy of formation of this interesting non-benzenoid hydrocarbon

  19. Molecular structure, vibrational analysis (IR and Raman) and quantum chemical investigations of 1-aminoisoquinoline

    Science.gov (United States)

    Sivaprakash, S.; Prakash, S.; Mohan, S.; Jose, Sujin P.

    2017-12-01

    Quantum chemical calculations of energy and geometrical parameters of 1-aminoisoquinoline [1-AIQ] were carried out by using DFT/B3LYP method using 6-311G (d,p), 6-311G++(d,p) and cc-pVTZ basis sets. The vibrational wavenumbers were computed for the energetically most stable, optimized geometry. The vibrational assignments were performed on the basis of potential energy distribution (PED) using VEDA program. The NBO analysis was done to investigate the intra molecular charge transfer of the molecule. The frontier molecular orbital (FMO) analysis was carried out and the chemical reactivity descriptors of the molecule were studied. The Mulliken charge analysis, molecular electrostatic potential (MEP), HOMO-LUMO energy gap and the related properties were also investigated at B3LYP level. The absorption spectrum of the molecule was studied from UV-Visible analysis by using time-dependent density functional theory (TD-DFT). Fourier Transform Infrared spectrum (FT-IR) and Raman spectrum of 1-AIQ compound were analyzed and recorded in the range 4000-400 cm-1 and 3500-100 cm-1 respectively. The experimentally determined wavenumbers were compared with those calculated theoretically and they complement each other.

  20. Spectroscopic studies and quantum chemical investigations of (3,4-dimethoxybenzylidene) propanedinitrile.

    Science.gov (United States)

    Gupta, Ujval; Kumar, Vinay; Singh, Vivek K; Kant, Rajni; Khajuria, Yugal

    2015-04-05

    The Fourier Transform Infrared (FTIR), Ultra-Violet Visible (UV-Vis) spectroscopy and Thermogravimetric (TG) analysis of (3,4-dimethoxybenzylidene) propanedinitrile have been carried out and investigated using quantum chemical calculations. The molecular geometry, harmonic vibrational frequencies, Mulliken charges, natural atomic charges and thermodynamic properties in the ground state have been investigated by using Hartree Fock Theory (HF) and Density Functional Theory (DFT) using B3LYP functional with 6-311G(d,p) basis set. Both HF and DFT methods yield good agreement with the experimental data. Vibrational modes are assigned with the help of Vibrational Energy Distribution Analysis (VEDA) program. UV-Visible spectrum was recorded in the spectral range of 190-800nm and the results are compared with the calculated values using TD-DFT approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results obtained from the studies of Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) are used to calculate molecular parameters like ionization potential, electron affinity, global hardness, electron chemical potential and global electrophilicity. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Synthesis, structural characterization and quantum chemical studies of silicon-containing benzoic acid derivatives

    Science.gov (United States)

    Zaltariov, Mirela-Fernanda; Cojocaru, Corneliu; Shova, Sergiu; Sacarescu, Liviu; Cazacu, Maria

    2016-09-01

    The present paper is concerned with the synthesis and molecular structure investigation of two new benzoic acid derivatives having trimethylsilyl tails, 4-((trimethylsilyl)methoxy) and 4-(3-(trimethylsilyl)propoxy)benzoic acids. The structures of the novel compounds have been confirmed by X-ray crystallography, Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H and 13C NMR). The theoretical studies of molecules were conducted by using the quantum chemical methods, such as Density Functional Theory (DFT B3LYP/6-31 + G**), Hartree-Fock (HF/6-31 + G**) and semiempirical computations (PM3, PM6 and PM7). The optimized molecular geometries have been found to be in good agreement with experimental structures resulted from the X-ray diffraction. The maximum electronic absorption bands observed at 272-287 nm (UV-vis spectra) have been assigned to π → π* transitions, which were in reasonable agreement with the time dependent density functional theory (TD-DFT) calculations. The computed vibrational frequencies by DFT method were assigned and compared with the experimental FTIR spectra. The mapped electrostatic potentials revealed the reactive sites, which corroborated the observation of the dimer supramolecular structures formed in the crystals by hydrogen-bonding. The energies of frontier molecular orbitals (HOMO and LUMO), energy gap, dipole moment and molecular descriptors for the new compounds were calculated and discussed.

  2. Thiobenzamide: Structure of a free molecule as studied by gas electron diffraction and quantum chemical calculations

    Science.gov (United States)

    Kolesnikova, Inna N.; Putkov, Andrei E.; Rykov, Anatolii N.; Shishkov, Igor F.

    2018-06-01

    The equilibrium (re) molecular structure of thiobenzamide along with rh1 structure has been determined in gas phase using gas electron-diffraction (GED) at about 127 °C and quantum-chemical calculations (QC). Rovibrational distance corrections to the thermal averaged GED structure have been computed with anharmonic force constants obtained at the MP2/cc-pVTZ level of theory. According to the results of GED and QC thiobenzamide exists as mixture of two non-planar enantiomers of C1 symmetry. The selected equilibrium geometrical parameters of thiobenzamide (re, Å and ∠e, deg) are the following: (Cdbnd S) = 1.641(4), (Csbnd N) = 1.352(2), (Csbnd C) = 1.478(9), (Cdbnd C)av = 1.395(2), CCN = 114.7(5), CCS = 123.4(5), C2C1C7S = 31(4), C6C1C7N = 29(4). The structure of thiobenzamide in the gas phase is markedly different to that in the literature for the single crystal. The differences between the gas and the solid structures are ascribed to the presence of intermolecular hydrogen bonding in the solid phase.

  3. FragIt: a tool to prepare input files for fragment based quantum chemical calculations.

    Directory of Open Access Journals (Sweden)

    Casper Steinmann

    Full Text Available Near linear scaling fragment based quantum chemical calculations are becoming increasingly popular for treating large systems with high accuracy and is an active field of research. However, it remains difficult to set up these calculations without expert knowledge. To facilitate the use of such methods, software tools need to be available to support these methods and help to set up reasonable input files which will lower the barrier of entry for usage by non-experts. Previous tools relies on specific annotations in structure files for automatic and successful fragmentation such as residues in PDB files. We present a general fragmentation methodology and accompanying tools called FragIt to help setup these calculations. FragIt uses the SMARTS language to locate chemically appropriate fragments in large structures and is applicable to fragmentation of any molecular system given suitable SMARTS patterns. We present SMARTS patterns of fragmentation for proteins, DNA and polysaccharides, specifically for D-galactopyranose for use in cyclodextrins. FragIt is used to prepare input files for the Fragment Molecular Orbital method in the GAMESS program package, but can be extended to other computational methods easily.

  4. Quantum chemical spectral characterization of CH2NH2+ for remote sensing of Titan's atmosphere

    Science.gov (United States)

    Thackston, Russell; Fortenberry, Ryan C.

    2018-01-01

    Cassini has shown that CH2NH2+ is likely present in relatively high abundance in Titan's upper atmosphere. Relatively little is known about this molecule even though it contains the same number of electrons as ethylene, a molecule of significance to Titan's chemistry. Any studies on CH2NH2+ with application to Titan or its atmospheric chemistry will have to be done remotely at this point with the end of the fruitful Cassini mission. Consequently, trusted quantum chemical techniques are utilized here to produce the rotational, vibrational, and rovibrational spectroscopic constants for CH2NH2+ for the first time. The methodology produces a tightly fit potential energy surface here that is well-behaved indicating a strong credence in the accuracy for the produced values. Most notably, the 884.1 cm-1 NH2 out-of-plane bend is the brightest of the vibrational frequencies reported here for CH2NH2+ , and an observed and unattributed feature in this spectral region has been documented but never assigned to a molecular carrier. Follow-up IR or radio observations making use of the 540 GHz to 660 GHz range with the 0.45 D molecular dipole moment will have to be undertaken in order to confirm this or any attribution, but the data provided in this work will greatly assist in any such studies related to CH2NH2+.

  5. A general intermolecular force field based on tight-binding quantum chemical calculations

    Science.gov (United States)

    Grimme, Stefan; Bannwarth, Christoph; Caldeweyher, Eike; Pisarek, Jana; Hansen, Andreas

    2017-10-01

    A black-box type procedure is presented for the generation of a molecule-specific, intermolecular potential energy function. The method uses quantum chemical (QC) information from our recently published extended tight-binding semi-empirical scheme (GFN-xTB) and can treat non-covalently bound complexes and aggregates with almost arbitrary chemical structure. The necessary QC information consists of the equilibrium structure, Mulliken atomic charges, charge centers of localized molecular orbitals, and also of frontier orbitals and orbital energies. The molecular pair potential includes model density dependent Pauli repulsion, penetration, as well as point charge electrostatics, the newly developed D4 dispersion energy model, Drude oscillators for polarization, and a charge-transfer term. Only one element-specific and about 20 global empirical parameters are needed to cover systems with nuclear charges up to radon (Z = 86). The method is tested for standard small molecule interaction energy benchmark sets where it provides accurate intermolecular energies and equilibrium distances. Examples for structures with a few hundred atoms including charged systems demonstrate the versatility of the approach. The method is implemented in a stand-alone computer code which enables rigid-body, global minimum energy searches for molecular aggregation or alignment.

  6. Quantum-Chemical Insights into the Self-Assembly of Carbon-Based Supramolecular Complexes

    Directory of Open Access Journals (Sweden)

    Joaquín Calbo

    2018-01-01

    Full Text Available Understanding how molecular systems self-assemble to form well-organized superstructures governed by noncovalent interactions is essential in the field of supramolecular chemistry. In the nanoscience context, the self-assembly of different carbon-based nanoforms (fullerenes, carbon nanotubes and graphene with, in general, electron-donor molecular systems, has received increasing attention as a means of generating potential candidates for technological applications. In these carbon-based systems, a deep characterization of the supramolecular organization is crucial to establish an intimate relation between supramolecular structure and functionality. Detailed structural information on the self-assembly of these carbon-based nanoforms is however not always accessible from experimental techniques. In this regard, quantum chemistry has demonstrated to be key to gain a deep insight into the supramolecular organization of molecular systems of high interest. In this review, we intend to highlight the fundamental role that quantum-chemical calculations can play to understand the supramolecular self-assembly of carbon-based nanoforms through a limited selection of supramolecular assemblies involving fullerene, fullerene fragments, nanotubes and graphene with several electron-rich π-conjugated systems.

  7. Interactions of ionic liquids and acetone: thermodynamic properties, quantum-chemical calculations, and NMR analysis.

    Science.gov (United States)

    Ruiz, Elia; Ferro, Victor R; Palomar, Jose; Ortega, Juan; Rodriguez, Juan Jose

    2013-06-20

    The interactions between ionic liquids (ILs) and acetone have been studied to obtain a further understanding of the behavior of their mixtures, which generally give place to an exothermic process, mutual miscibility, and negative deviation of Raoult's law. COSMO-RS was used as a suitable computational method to systematically analyze the excess enthalpy of IL-acetone systems (>300), in terms of the intermolecular interactions contributing to the mixture behavior. Spectroscopic and COSMO-RS results indicated that acetone, as a polar compound with strong hydrogen bond acceptor character, in most cases, establishes favorable hydrogen bonding with ILs. This interaction is strengthened by the presence of an acidic cation and an anion with dispersed charge and non-HB acceptor character in the IL. COSMO-RS predictions indicated that gas-liquid and vapor-liquid equilibrium data for IL-acetone systems can be finely tuned by the IL selection, that is, acting on the intermolecular interactions between the molecular and ionic species in the liquid phase. NMR measurements for IL-acetone mixtures at different concentrations were also carried out. Quantum-chemical calculations by using molecular clusters of acetone and IL species were finally performed. These results provided additional evidence of the main role played by hydrogen bonding in the behavior of systems containing ILs and HB acceptor compounds, such as acetone.

  8. Synthesis, vibrational and quantum chemical investigations of hydrogen bonded complex betaine dihydrogen selenite

    Science.gov (United States)

    Arjunan, V.; Marchewka, Mariusz K.; Kalaivani, M.

    2012-10-01

    The molecular complex of betaine with selenious acid namely, betaine dihydrogen selenite (C5H13NO5Se, BDHSe) was synthesised by the reaction of betaine and SeO2 in a 1:1:1 solution of isopropanol, methanol and water. Crystals were grown from this solution by cooling to 253 K for few days. The complex was formed without accompanying proton transfer from selenious acid molecule to betaine. The complete vibrational assignments and analysis of BDHSe have been performed by FTIR, FT-Raman and far-infrared spectral studies. More support on the experimental findings was added from the quantum chemical studies performed with DFT (B3LYP) method using 6-311++G∗∗, 6-31G∗∗, cc-pVDZ and 3-21G basis sets. The structural parameters, energies, thermodynamic parameters and the NBO charges of BDHSe were determined by the DFT method. The 1H and 13C isotropic chemical shifts (δ ppm) of BDHSe with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. SHG experiment was carried out using Kurtz-Perry powder technique. The efficiency of second harmonic generation for BDHSe was estimated relatively to KDP: deff = 0.97 deff (KDP).

  9. Structure activity studies of an analgesic drug tapentadol hydrochloride by spectroscopic and quantum chemical methods

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Marchewka, M. K.; Mohan, S.; Yang, Haifeng

    2015-11-01

    Tapentadol is a novel opioid pain reliever drug with a dual mechanism of action, having potency between morphine and tramadol. Quantum chemical calculations have been carried out for tapentadol hydrochloride (TAP.Cl) to determine the properties. The geometry is optimised and the structural properties of the compound were determined from the optimised geometry by B3LYP method using 6-311++G(d,p), 6-31G(d,p) and cc-pVDZ basis sets. FT-IR and FT-Raman spectra are recorded in the solid phase in the region of 4000-400 and 4000-100 cm-1, respectively. Frontier molecular orbital energies, LUMO-HOMO energy gap, ionisation potential, electron affinity, electronegativity, hardness and chemical potential are also calculated. The stability of the molecule arising from hyperconjugative interactions and charge delocalisation has been analysed using NBO analysis. The 1H and 13C nuclear magnetic resonance chemical shifts of the molecule are analysed.

  10. From pirazoloquinolines to annulated azulene dyes: UV-VIS spectroscopy and quantum chemical study

    International Nuclear Information System (INIS)

    Gasiorski, P.; Danel, K.S.; Matusiewicz, M.; Uchacz, T.; Kityk, A.V.

    2010-01-01

    Paper reports UV-Vis absorption and photoluminescence spectra of 6-R derivatives (R=CH 3 , O-CH 3 , C(C 6 H 5 ) 3 , C 6 H 5 -N-C 10 H 7 ) of 4-(2-chlorophenyl)-1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline, belonging to pyrazoloquinoline (PQ) family, likewise its regioisomeric products 10-R derivatives of 6-phenyl-6H-5,6,7-triazadibenzo[f,h]naphtho[3,2,1-cd]azulene representing cyclized seven-membered annulated azulene (AA) dyes. Cyclization of PQs into AAs is accompanied by a significant red shift of the first optical absorption band. This finding agrees with the results of quantum-chemical calculations performed by means of the semiempirical method PM3. As the solvent polarity rises all the dyes exhibit a blue shift of the first absorption band and a red shift of the fluorescence band. Such opposite trends in solvatochromic behavior have been reproduced within the semiempirical calculations in combination with the Lippert-Mataga dielectric polarization model. Depending on solvent polarity AA dyes emit light in the green, green-yellow or orange range of the visible spectrum what may be of interest for potential luminescent or electroluminescent applications.

  11. ExcelAutomat: a tool for systematic processing of files as applied to quantum chemical calculations

    Science.gov (United States)

    Laloo, Jalal Z. A.; Laloo, Nassirah; Rhyman, Lydia; Ramasami, Ponnadurai

    2017-07-01

    The processing of the input and output files of quantum chemical calculations often necessitates a spreadsheet as a key component of the workflow. Spreadsheet packages with a built-in programming language editor can automate the steps involved and thus provide a direct link between processing files and the spreadsheet. This helps to reduce user-interventions as well as the need to switch between different programs to carry out each step. The ExcelAutomat tool is the implementation of this method in Microsoft Excel (MS Excel) using the default Visual Basic for Application (VBA) programming language. The code in ExcelAutomat was adapted to work with the platform-independent open-source LibreOffice Calc, which also supports VBA. ExcelAutomat provides an interface through the spreadsheet to automate repetitive tasks such as merging input files, splitting, parsing and compiling data from output files, and generation of unique filenames. Selected extracted parameters can be retrieved as variables which can be included in custom codes for a tailored approach. ExcelAutomat works with Gaussian files and is adapted for use with other computational packages including the non-commercial GAMESS. ExcelAutomat is available as a downloadable MS Excel workbook or as a LibreOffice workbook.

  12. Silicon Oxysulfide, OSiS: Rotational Spectrum, Quantum-Chemical Calculations, and Equilibrium Structure.

    Science.gov (United States)

    Thorwirth, Sven; Mück, Leonie Anna; Gauss, Jürgen; Tamassia, Filippo; Lattanzi, Valerio; McCarthy, Michael C

    2011-06-02

    Silicon oxysulfide, OSiS, and seven of its minor isotopic species have been characterized for the first time in the gas phase at high spectral resolution by means of Fourier transform microwave spectroscopy. The equilibrium structure of OSiS has been determined from the experimental data using calculated vibration-rotation interaction constants. The structural parameters (rO-Si = 1.5064 Å and rSi-S = 1.9133 Å) are in very good agreement with values from high-level quantum chemical calculations using coupled-cluster techniques together with sophisticated additivity and extrapolation schemes. The bond distances in OSiS are very short in comparison with those in SiO and SiS. This unexpected finding is explained by the partial charges calculated for OSiS via a natural population analysis. The results suggest that electrostatic effects rather than multiple bonding are the key factors in determining bonding in this triatomic molecule. The data presented provide the spectroscopic information needed for radio astronomical searches for OSiS.

  13. An FT-Raman, FT-IR, and Quantum Chemical Investigation of Stanozolol and Oxandrolone

    Directory of Open Access Journals (Sweden)

    Tibebe Lemma

    2017-12-01

    Full Text Available We have studied the Fourier Transform Infrared (FT-IR and the Fourier transform Raman (FT-Raman spectra of stanozolol and oxandrolone, and we have performed quantum chemical calculations based on the density functional theory (DFT with a B3LYP/6-31G (d, p level of theory. The FT-IR and FT-Raman spectra were collected in a solid phase. The consistency between the calculated and experimental FT-IR and FT-Raman data indicates that the B3LYP/6-31G (d, p can generate reliable geometry and related properties of the title compounds. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution. The good agreement between the experimental and theoretical spectra allowed positive assignment of the observed vibrational absorption bands. Finally, the calculation results were applied to simulate the Raman and IR spectra of the title compounds, which show agreement with the observed spectra.

  14. Microwave spectrum, structure, and quantum chemical studies of a compound of potential astrochemical and astrobiological interest: Z-3-amino-2-propenenitrile.

    Science.gov (United States)

    Askeland, Eva; Møllendal, Harald; Uggerud, Einar; Guillemin, Jean-Claude; Aviles Moreno, Juan-Ramon; Demaison, Jean; Huet, Thérèse R

    2006-11-23

    Z-3-Amino-2-propenenitrile, H2NCH=CHCN, a compound of astrochemical and astrobiological interest, has been studied by Stark and Fourier transform microwave spectroscopy along with eight of its isotopologues; the synthesis of five of these are reported. The spectra of the ground vibrational state and of three vibrationally excited states belonging to the two lowest normal modes were assigned for the parent species, whereas the ground states were assigned for the isotopologues. The frequency of the lowest in-plane bending fundamental vibration was determined to be 152(20) cm(-1) and the frequency of the lowest out-of-plane fundamental mode was found to be 176(20) cm(-1) by relative intensity measurements. A delicate problem is whether this compound is planar or slightly nonplanar. It was found that the rotational constants of the nine species cannot be used to conclude definitely whether the molecule is planar or not. The experimental dipole moment is mu(a) = 16.45(12), mu(b) = 2.86(6), mu(c) = 0 (assumed), and mu(tot.) = 16.70(12) x 10(-30) C m [5.01(4) D]. The quadrupole coupling constants of the two nitrogen nuclei are chi(aa) = -1.4917(21) and chi(cc) = 1.5644(24) MHz for the nitrogen atom of the cyano group and chi(aa) = 1.7262(18) and chi(cc) = -4.0591(17) MHz for the nitrogen atom of the amino group. Extensive quantum-chemical calculations have been performed, and the results obtained from these calculations have been compared with the experimental values. The equilibrium structures of vinylamine, vinyl cyanide, and Z-3-amino-2-propenenitrile have been calculated. These calculations have established that the equilibrium structure of the title compound is definitely nonplanar. However, the MP2/VQZ energy difference between the planar and nonplanar forms is small, only -423 J/mol. Z-Amino-2-propenenitrile and E-3-amino-2-propenenitrile are formed simply by mixing ammonia and cyanoacetylene at room temperature. A plausible reaction path has been modeled. G3

  15. Kinetic-quantum chemical model for catalytic cycles: the Haber-Bosch process and the effect of reagent concentration.

    Science.gov (United States)

    Kozuch, Sebastian; Shaik, Sason

    2008-07-03

    A combined kinetic-quantum chemical model is developed with the goal of estimating in a straightforward way the turnover frequency (TOF) of catalytic cycles, based on the state energies obtained by quantum chemical calculations. We describe how the apparent activation energy of the whole cycle, so-called energetic span (delta E), is influenced by the energy levels of two species: the TOF determining transition state (TDTS) and the TOF determining intermediate (TDI). Because these key species need not be adjoining states, we conclude that for catalysis there are no rate-determining steps, only rate determining states. In addition, we add here the influence of reactants concentrations. And, finally, the model is applied to the Haber-Bosch process of ammonia synthesis, for which we show how to calculate which catalyst will be the most effective under specific reagents conditions.

  16. Structural and vibrational spectral investigations of melaminium maleate monohydrate by FTIR, FT-Raman and quantum chemical calculations

    Science.gov (United States)

    Arjunan, V.; Kalaivani, M.; Marchewka, M. K.; Mohan, S.

    2013-04-01

    The structural investigations of the molecular complex of melamine with maleic acid, namely melaminium maleate monohydrate have been carried out by quantum chemical methods in addition to FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical studies were performed with DFT (B3LYP) method using 6-31G**, cc-pVDZ and 6-311++G** basis sets to determine the energy, structural and thermodynamic parameters of melaminium maleate monohydrate. The hydrogen atom from maleic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak Osbnd H⋯O and Nsbnd H⋯O hydrogen bonds shows notable vibrational effects.

  17. Structural and vibrational spectral investigations of melaminium maleate monohydrate by FTIR, FT-Raman and quantum chemical calculations.

    Science.gov (United States)

    Arjunan, V; Kalaivani, M; Marchewka, M K; Mohan, S

    2013-04-15

    The structural investigations of the molecular complex of melamine with maleic acid, namely melaminium maleate monohydrate have been carried out by quantum chemical methods in addition to FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical studies were performed with DFT (B3LYP) method using 6-31G(**), cc-pVDZ and 6-311++G(**) basis sets to determine the energy, structural and thermodynamic parameters of melaminium maleate monohydrate. The hydrogen atom from maleic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak OH···O and NH···O hydrogen bonds shows notable vibrational effects. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Dependence of the extraction capacity of neutral bidentate organophosphorus compounds on their structure: a quantum chemical study

    International Nuclear Information System (INIS)

    Sudarushkin, S.K.; Morgalyuk, V.P.; Tananaev, I.G.; Gribov, L.A.; Myasoedov, B.F.

    2006-01-01

    Correlations between the extraction capacities and molecular structures of organic phosphorus compounds (reagents for extraction of transplutonium elements from spent nuclear fuel) were studied using a quantum chemical approach. The results of calculations are in qualitative agreement with experimental data. The approach proposed can be used for analysis of the extraction properties of all classes of organic phosphorus compounds and also for prediction of the most efficient organic phosphorus extractants with preset properties [ru

  19. A quantum-chemical study of oxygen-vacancy defects in PbTiO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Stashans, Arvids [Laboratorio de Fisica, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)]. E-mail: arvids@utpl.edu.ec; Serrano, Sheyla [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador); Escuela de Ingenierias, Universidad Politecnica Salesiana, Campus Sur, Rumichaca s/n y Moran Valverde, Apartado 17-12-536, Quito (Ecuador); Medina, Paul [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador)

    2006-05-31

    Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO{sub 3} crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results.

  20. A quantum-chemical study of oxygen-vacancy defects in PbTiO3 crystals

    International Nuclear Information System (INIS)

    Stashans, Arvids; Serrano, Sheyla; Medina, Paul

    2006-01-01

    Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO 3 crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results

  1. The structure and conformations of piracetam (2-oxo-1-pyrrolidineacetamide): Gas-phase electron diffraction and quantum chemical calculations

    Science.gov (United States)

    Ksenafontov, Denis N.; Moiseeva, Natalia F.; Khristenko, Lyudmila V.; Karasev, Nikolai M.; Shishkov, Igor F.; Vilkov, Lev V.

    2010-12-01

    The geometric structure of piracetam was studied by quantum chemical calculations (DFT and ab initio), gas electron diffraction (GED), and FTIR spectroscopy. Two stable mirror symmetric isomers of piracetam were found. The conformation of pyrrolidine ring is an envelope in which the C4 atom deviates from the ring plane, the angle between the planes (C3 sbnd C4 sbnd C5) and (C2 sbnd C3 sbnd C5) is 154.1°. The direction of the deviation is the same as that of the side acetamide group. The piracetam molecule is stabilized in the gas phase by an intramolecular hydrogen bond between the N9H 2 group and the oxygen O6, bonded to C2. The principal structural parameters ( re, Å and ∠e, degrees; uncertainties are 3 σLS values) were found to be: r(С3 sbnd С4) = 1.533(1), r(C4 sbnd C5) = 1.540(1), r(N1 sbnd C5) = 1.456(1), r(C2 sbnd C3) = 1.520(1), r(N1 sbnd C7) = 1.452(1), r(C7 sbnd C8) = 1.537(1), r(N1 sbnd C2) = 1.365(2), r(C8 sbnd N9) = 1.360(2), r(C2 dbnd O6) = 1.229(1), r(C8 dbnd O10) = 1.221(1), ∠C2 sbnd N1 sbnd C5 = 113.4(6), ∠N1 sbnd C2 sbnd C3 = 106.9(6), ∠N1 sbnd C7 sbnd C8 = 111.9(6), ∠C7 sbnd C8 sbnd N9 = 112.5(6), ∠N1 sbnd C2 sbnd O6 = 123.0(4), ∠C3 sbnd N1 sbnd C7 = 120.4(4), ∠C7 sbnd C8 sbnd O10 = 120.2(4), ∠C5 sbnd N1 sbnd C2 sbnd O6 = 170(6), ∠C3 sbnd C2 sbnd N1 sbnd C7 = 178(6), ∠C2 sbnd N1 sbnd C7 sbnd C8 = 84.2, ∠N1 sbnd C7 sbnd C8 sbnd O10 = 111.9.

  2. Adaptive Neuro-Fuzzy Inference System Applied QSAR with Quantum Chemical Descriptors for Predicting Radical Scavenging Activities of Carotenoids.

    Science.gov (United States)

    Jhin, Changho; Hwang, Keum Taek

    2015-01-01

    One of the physiological characteristics of carotenoids is their radical scavenging activity. In this study, the relationship between radical scavenging activities and quantum chemical descriptors of carotenoids was determined. Adaptive neuro-fuzzy inference system (ANFIS) applied quantitative structure-activity relationship models (QSAR) were also developed for predicting and comparing radical scavenging activities of carotenoids. Semi-empirical PM6 and PM7 quantum chemical calculations were done by MOPAC. Ionisation energies of neutral and monovalent cationic carotenoids and the product of chemical potentials of neutral and monovalent cationic carotenoids were significantly correlated with the radical scavenging activities, and consequently these descriptors were used as independent variables for the QSAR study. The ANFIS applied QSAR models were developed with two triangular-shaped input membership functions made for each of the independent variables and optimised by a backpropagation method. High prediction efficiencies were achieved by the ANFIS applied QSAR. The R-square values of the developed QSAR models with the variables calculated by PM6 and PM7 methods were 0.921 and 0.902, respectively. The results of this study demonstrated reliabilities of the selected quantum chemical descriptors and the significance of QSAR models.

  3. Adaptive Neuro-Fuzzy Inference System Applied QSAR with Quantum Chemical Descriptors for Predicting Radical Scavenging Activities of Carotenoids.

    Directory of Open Access Journals (Sweden)

    Changho Jhin

    Full Text Available One of the physiological characteristics of carotenoids is their radical scavenging activity. In this study, the relationship between radical scavenging activities and quantum chemical descriptors of carotenoids was determined. Adaptive neuro-fuzzy inference system (ANFIS applied quantitative structure-activity relationship models (QSAR were also developed for predicting and comparing radical scavenging activities of carotenoids. Semi-empirical PM6 and PM7 quantum chemical calculations were done by MOPAC. Ionisation energies of neutral and monovalent cationic carotenoids and the product of chemical potentials of neutral and monovalent cationic carotenoids were significantly correlated with the radical scavenging activities, and consequently these descriptors were used as independent variables for the QSAR study. The ANFIS applied QSAR models were developed with two triangular-shaped input membership functions made for each of the independent variables and optimised by a backpropagation method. High prediction efficiencies were achieved by the ANFIS applied QSAR. The R-square values of the developed QSAR models with the variables calculated by PM6 and PM7 methods were 0.921 and 0.902, respectively. The results of this study demonstrated reliabilities of the selected quantum chemical descriptors and the significance of QSAR models.

  4. Exploring the role of quantum chemical descriptors in modeling acute toxicity of diverse chemicals to Daphnia magna.

    Science.gov (United States)

    Reenu; Vikas

    2015-09-01

    Various quantum-mechanically computed molecular and thermodynamic descriptors along with physico-chemical, electrostatic and topological descriptors are compared while developing quantitative structure-activity relationships (QSARs) for the acute toxicity of 252 diverse organic chemicals towards Daphnia magna. QSAR models based on the quantum-chemical descriptors, computed with routinely employed advanced semi-empirical and ab-initio methods, along with the electron-correlation contribution (CORR) of the descriptors, are analyzed for the external predictivity of the acute toxicity. The models with reliable internal stability and external predictivity are found to be based on the HOMO energy along with the physico-chemical, electrostatic and topological descriptors. Besides this, the total energy and electron-correlation energy are also observed as highly reliable descriptors, suggesting that the intra-molecular interactions between the electrons play an important role in the origin of the acute toxicity, which is in fact an unexplored phenomenon. The models based on quantum-chemical descriptors such as chemical hardness, absolute electronegativity, standard Gibbs free energy and enthalpy are also observed to be reliable. A comparison of the robust models based on the quantum-chemical descriptors computed with various quantum-mechanical methods suggests that the advanced semi-empirical methods such as PM7 can be more reliable than the ab-initio methods which are computationally more expensive. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. A quantum-chemical perspective into low optical-gap polymers for highly-efficient organic solar cells

    KAUST Repository

    Risko, Chad

    2011-03-15

    The recent and rapid enhancement in power conversion efficiencies of organic-based, bulk heterojunction solar cells has been a consequence of both improved materials design and better understanding of the underlying physical processes involved in photocurrent generation. In this Perspective, we first present an overview of the application of quantum-chemical techniques to study the intrinsic material properties and molecular- and nano-scale processes involved in device operation. In the second part, these quantum-chemical tools are applied to an oligomer-based study on a collection of donor-acceptor copolymers that have been used in the highest-efficiency solar cell devices reported to date. The quantum-chemical results are found to be in good agreement with the empirical data related to the electronic and optical properties. In particular, they provide insight into the natures of the electronic excitations responsible for the near-infrared/visible absorption profiles, as well as into the energetics of the low-lying singlet and triplet states. These results lead to a better understanding of the inherent differences among the materials, and highlight the usefulness of quantum chemistry as an instrument for material design. Importantly, the results also point to the need to continue the development of integrated, multi scale modeling approaches to provide a thorough understanding of the materials properties. © The Royal Society of Chemistry 2011.

  6. Increasing Understanding of Public Problems and Policies; A Group Study of Four Topics in the Field of Extension Education.

    Science.gov (United States)

    Farm Foundation, Chicago, IL.

    Sixteen essays pertaining to agricultural extension education were the basis of the 18th National Agricultural Policy Conference, held September 10-18, 1968, at Sequoyah State Park, Wagoner, Oklahoma. Individual topics of papers include leadership training, Iowa State welfare, low income area community development, an urban extension pilot…

  7. Radical cations in radiation chemistry of aldehydes. ESR study and quantum chemical analysis

    International Nuclear Information System (INIS)

    Belevskii, V.N.; Tyurin, D.A.; Chuvilkin, N.D.

    1998-01-01

    Quantum-chemical (MNDO-UHF) calculations of electronic, spin and energy characteristics of radical cations (RC) of ethanal, propanal, butanal, and pentanal and their distonic isomers were performed. The calculations both with 'frozen' (vertical ionization) and completely optimize geometry (adiabatic approximation) were made. It was been shown that the most positive charge and spin population are localized at O atoms and adjacent C atom as well as at aldehyde protons. The C-H bonds corresponding to those protons as well as neighboring C-O and C-C bonds are considerable weaker (longer) in radical cations as compared to their neutral precursors. That is why such reaction centers are apt to deprotonation with the formation of acyl radical as well as to α- and β-splitting (scission) which are well-known from aldehydes mass-spectra. Our calculations shown that distonic RC (products of intramolecular H-atom transfer) are more stable as compare to their classical isomers: e.g. the difference in energy ΔE = -0.95 eV, -1.2 eV, and -1.5 eV for tree distonic isomers of butanal RC as compare to classical isomer, ΔE -1.2 eV for distonic RC of ethanal. The results of calculations are effectively correlated with ESR data obtained in freonic solutions, X- and gamma-irradiated at 77 K and in liquid aldehydes, X-irradiated by using 2,4,6-tri-tert-burylnitrosobenzene (BNB) and t-BuNO (NtB) as a spin traps. (author)

  8. Theoretical study of the electronic structure of f-element complexes by quantum chemical methods

    International Nuclear Information System (INIS)

    Vetere, V.

    2002-09-01

    This thesis is related to comparative studies of the chemical properties of molecular complexes containing lanthanide or actinide trivalent cations, in the context of the nuclear waste disposal. More precisely, our aim was a quantum chemical analysis of the metal-ligand bonding in such species. Various theoretical approaches were compared, for the inclusion of correlation (density functional theory, multiconfigurational methods) and of relativistic effects (relativistic scalar and 2-component Hamiltonians, relativistic pseudopotentials). The performance of these methods were checked by comparing computed structural properties to published experimental data, on small model systems: lanthanide and actinide tri-halides and on X 3 M-L species (X=F, Cl; M=La, Nd, U; L = NH 3 , acetonitrile, CO). We have thus shown the good performance of density functionals combined with a quasi-relativistic method, as well as of gradient-corrected functionals associated with relativistic pseudopotentials. In contrast, functionals including some part of exact exchange are less reliable to reproduce experimental trends, and we have given a possible explanation for this result . Then, a detailed analysis of the bonding has allowed us to interpret the discrepancies observed in the structural properties of uranium and lanthanides complexes, based on a covalent contribution to the bonding, in the case of uranium(III), which does not exist in the lanthanide(III) homologues. Finally, we have examined more sizeable systems, closer to experimental species, to analyse the influence of the coordination number, of the counter-ions and of the oxidation state of uranium, on the metal-ligand bonding. (author)

  9. Comparison of sugar molecule decomposition through glucose and fructose: a high-level quantum chemical study.

    Energy Technology Data Exchange (ETDEWEB)

    Assary, R. S.; Curtiss, L. A. (Center for Nanoscale Materials); ( MSD); (Northwestern Univ.)

    2012-02-01

    Efficient chemical conversion of biomass is essential to produce sustainable energy and industrial chemicals. Industrial level conversion of glucose to useful chemicals, such as furfural, hydroxymethylfurfural, and levulinic acid, is a major step in the biomass conversion but is difficult because of the formation of undesired products and side reactions. To understand the molecular level reaction mechanisms involved in the decomposition of glucose and fructose, we have carried out high-level quantum chemical calculations [Gaussian-4 (G4) theory]. Selective 1,2-dehydration, keto-enol tautomerization, isomerization, retro-aldol condensation, and hydride shifts of glucose and fructose molecules were investigated. Detailed kinetic and thermodynamic analyses indicate that, for acyclic glucose and fructose molecules, the dehydration and isomerization require larger activation barriers compared to the retro-aldol reaction at 298 K in neutral medium. The retro-aldol reaction results in the formation of C2 and C4 species from glucose and C3 species from fructose. The formation of the most stable C3 species, dihydroxyacetone from fructose, is thermodynamically downhill. The 1,3-hydride shift leads to the cleavage of the C-C bond in the acyclic species; however, the enthalpy of activation is significantly higher (50-55 kcal/mol) than that of the retro-aldol reaction (38 kcal/mol) mainly because of the sterically hindered distorted four-membered transition state compared to the hexa-membered transition state in the retro-aldol reaction. Both tautomerization and dehydration are catalyzed by a water molecule in aqueous medium; however, water has little effect on the retro-aldol reaction. Isomerization of glucose to fructose and glyceraldehyde to dihydroxyacetone proceeds through hydride shifts that require an activation enthalpy of about 40 kcal/mol at 298 K in water medium. This investigation maps out accurate energetics of the decomposition of glucose and fructose molecules

  10. Photophysics of α-furil at room temperature and 77 K: Spectroscopic and quantum chemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Pronab; Chattopadhyay, Nitin, E-mail: nitin.chattopadhyay@yahoo.com [Department of Chemistry, Jadavpur University, Kolkata 700 032 (India)

    2016-06-21

    Steady state and time resolved spectroscopic measurements have been exploited to assign the emissions from different conformations of α-furil (2, 2′-furil) in solution phase at room temperature as well as cryogen (liquid nitrogen, LN{sub 2}) frozen matrices of ethanol and methylcyclohexane. Room temperature studies reveal a single fluorescence from the trans-planar conformer of the fluorophore or two fluorescence bands coming from the trans-planar and the relaxed skew forms depending on excitation at the nπ{sup ∗} or the ππ{sup ∗} absorption band, respectively. Together with the fluorescence bands, the LN{sub 2} studies in both the solvents unambiguously ascertain two phosphorescence emissions with lifetimes 5 ± 0.3 ms (trans-planar triplet) and 81 ± 3 ms (relaxed skew triplet). Quantum chemical calculations have been performed using density functional theory at CAM-B3LYP/6-311++G{sup ∗∗} level to prop up the spectroscopic surveillance. The simulated potential energy curves (PECs) illustrate that α-furil is capable of giving two emissions from each of the S{sub 1} and the T{sub 1} states—one corresponding to the trans-planar and the other to the relaxed skew conformation. Contrary to the other 1,2-dicarbonyl molecular systems like benzil and α-naphthil, α-furil does not exhibit any fluorescence from its second excited singlet (S{sub 2}) state. This is ascribed to the proximity of the minimum of the PEC of the S{sub 2} state and the hill-top of the PEC of the S{sub 1} state.

  11. DFT simulation, quantum chemical electronic structure, spectroscopic and structure-activity investigations of 2-benzothiazole acetonitrile.

    Science.gov (United States)

    Arjunan, V; Thillai Govindaraja, S; Jose, Sujin P; Mohan, S

    2014-07-15

    The Fourier transform infrared and FT-Raman spectra of 2-benzothiazole acetonitrile (BTAN) have been recorded in the range 4000-450 and 4000-100 cm(-1) respectively. The conformational analysis of the compound has been carried out to obtain the stable geometry of the compound. The complete vibrational assignment and analysis of the fundamental modes of the compound are carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The experimental vibrational frequencies are compared with the wavenumbers derived theoretically by B3LYP gradient calculations employing the standard 6-31G(**), high level 6-311++G(**) and cc-pVTZ basis sets. The structural parameters, thermodynamic properties and vibrational frequencies of the normal modes obtained from the B3LYP methods are in good agreement with the experimental data. The (1)H (400 MHz; CDCl3) and (13)C (100 MHz;CDCl3) nuclear magnetic resonance (NMR) spectra are also recorded. The electronic properties, the energies of the highest occupied and lowest unoccupied molecular orbitals are measured by DFT approach. The kinetic stability of the molecule has been determined from the frontier molecular orbital energy gap. The charges of the atoms and the structure-chemical reactivity relations of the compound are determined by its chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors by conceptual DFT methods. The non-linear optical properties of the compound have been discussed by measuring the polarisability and hyperpolarisability tensors. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Structural studies of crystals of organic and organoelement compounds using modern quantum chemical calculations within the framework of the density functional theory

    International Nuclear Information System (INIS)

    Korlyukov, Alexander A; Antipin, Mikhail Yu

    2012-01-01

    The review generalizes the results of structural studies of crystals of organic and organometallic compounds by modern quantum chemical calculations within the framework of the density functional theory reported in the last decade. Features of the software for such calculations are discussed. Examples of the use of quantum chemical calculations for the studies of the electronic structure, spectroscopic and other physicochemical properties of molecular crystals are presented. The bibliography includes 223 references.

  13. Vibronic coupling in molecular crystals: A Franck-Condon Herzberg-Teller model of H-aggregate fluorescence based on quantum chemical cluster calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wykes, M., E-mail: mikewykes@gmail.com; Parambil, R.; Gierschner, J. [Madrid Institute for Advanced Studies, IMDEA Nanoscience, Calle Faraday 9, Campus Cantoblanco, 28049 Madrid (Spain); Beljonne, D. [Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons (Belgium)

    2015-09-21

    Here, we present a general approach to treating vibronic coupling in molecular crystals based on atomistic simulations of large clusters. Such clusters comprise model aggregates treated at the quantum chemical level embedded within a realistic environment treated at the molecular mechanics level. As we calculate ground and excited state equilibrium geometries and vibrational modes of model aggregates, our approach is able to capture effects arising from coupling to intermolecular degrees of freedom, absent from existing models relying on geometries and normal modes of single molecules. Using the geometries and vibrational modes of clusters, we are able to simulate the fluorescence spectra of aggregates for which the lowest excited state bears negligible oscillator strength (as is the case, e.g., ideal H-aggregates) by including both Franck-Condon (FC) and Herzberg-Teller (HT) vibronic transitions. The latter terms allow the adiabatic excited state of the cluster to couple with vibrations in a perturbative fashion via derivatives of the transition dipole moment along nuclear coordinates. While vibronic coupling simulations employing FC and HT terms are well established for single-molecules, to our knowledge this is the first time they are applied to molecular aggregates. Here, we apply this approach to the simulation of the low-temperature fluorescence spectrum of para-distyrylbenzene single-crystal H-aggregates and draw comparisons with coarse-grained Frenkel-Holstein approaches previously extensively applied to such systems.

  14. Exploratory double-blind, parallel-group, placebo-controlled extension study of edaravone (MCI-186) in amyotrophic lateral sclerosis.

    Science.gov (United States)

    2017-10-01

    Following the first phase III study of edaravone for amyotrophic lateral sclerosis (ALS), this extension study was performed to evaluate longer-term efficacy and safety. Patients given edaravone in the first 24-week phase III study (Cycles 1-6) were randomised to edaravone (E-E) or placebo (E-P) in the subsequent 24-week double-blind period (Cycles 7-12). Patients given placebo in phase III were switched to edaravone (P-E). Subsequently, all patients received edaravone for 12 weeks (Cycles 13-15). Efficacy endpoints included revised ALS Functional Rating Scale (ALSFRS-R) score. Analysis populations were the full analysis set (FAS) and the efficacy-expected subpopulation (EESP) defined by post-hoc analysis of the first phase III study. The least-squares mean and standard error of the intergroup difference (E-E vs. E-P) of change in the ALSFRS-R score from Cycles 7-12 was 1.16 ± 0.93 (p = 0.2176) in the FAS, and 1.85 ± 1.14 (p = 0.1127) in the EESP. The ALSFRS-R score changed almost linearly in the E-E group throughout Cycles 1-15 (60 weeks). The incidence of serious adverse events associated with ALS progression was higher in E-E than in E-P. Edaravone might have potential efficacy for up to 15 cycles when used to treat patients in the EESP with careful safety monitoring.

  15. Quantum chemical analysis of Со2+ aqua complexes electrochemical reduction

    Directory of Open Access Journals (Sweden)

    Viktor F. Vargalyuk

    2017-11-01

    Full Text Available Based on the analysis of quantum chemical calculations results (GAMESS, density functional theory, B3LYP method as to [Co(H2On]z(H2O6–n clusters for z = 0, 1, 2 and n=1÷6, it has been demonstrated that electrochemical reduction of [Co(H2O6]2+ aqua complexes runs stage-wise. At the first stage, an electron injected into the [Co(H2O6]2+ complex is entirely located in the orbital of the central atom, as z(Co herewith changes from +1.714 е to +0.777 е. The weakening of Со–ОН2 bonds leads to decomposition of resulting [Co(H2O6]+ particles into two energetically related forms – [Co(H2O4]+ and [Co(H2O3]+. Further reduction of these intermediates runs differently. Electron injection into the [Co(H2O3]+ intermediate terminatesthe transition of Со2+-ions to Со0 z(Co= –0.264 е. This process is accompanied by rapid decomposition of [Co(H2O3]0 product into monohydrate atom of cobalt Со(Н2О. On the contrary, electron injection into the [Co(H2O4]+ intermediate leads to emergence of a specific structure – [Co+(H2O–(Н2О3]¹0, whereby the electron is located in the atoms of cobalt only by 28%, and by 72% in cobalt-coordinated water molecules, clearly focusing on one of the. In this molecule, z(H2O changes from +0.148 е to –0.347 е. There is an assumption that a non-equilibrium [Co+(H2O–(Н2О3]0¹ form transits to [Co(ОH(Н2О3]0 hydroxo-form, which further disproportionates turning into Co(ОH2 hydroxide. In order to reduce the impact of this unfavorable reaction pathway on the overall reaction rate Со2+ + 2ē = Со0, we suggest raising the temperature to ensure complete dissociation of [Co(H2O4]+ to [Co(H2O3]+.

  16. CRITIC2: A program for real-space analysis of quantum chemical interactions in solids

    Science.gov (United States)

    Otero-de-la-Roza, A.; Johnson, Erin R.; Luaña, Víctor

    2014-03-01

    We present CRITIC2, a program for the analysis of quantum-mechanical atomic and molecular interactions in periodic solids. This code, a greatly improved version of the previous CRITIC program (Otero-de-la Roza et al., 2009), can: (i) find critical points of the electron density and related scalar fields such as the electron localization function (ELF), Laplacian, … (ii) integrate atomic properties in the framework of Bader’s Atoms-in-Molecules theory (QTAIM), (iii) visualize non-covalent interactions in crystals using the non-covalent interactions (NCI) index, (iv) generate relevant graphical representations including lines, planes, gradient paths, contour plots, atomic basins, … and (v) perform transformations between file formats describing scalar fields and crystal structures. CRITIC2 can interface with the output produced by a variety of electronic structure programs including WIEN2k, elk, PI, abinit, Quantum ESPRESSO, VASP, Gaussian, and, in general, any other code capable of writing the scalar field under study to a three-dimensional grid. CRITIC2 is parallelized, completely documented (including illustrative test cases) and publicly available under the GNU General Public License. Catalogue identifier: AECB_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECB_v2_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: yes No. of lines in distributed program, including test data, etc.: 11686949 No. of bytes in distributed program, including test data, etc.: 337020731 Distribution format: tar.gz Programming language: Fortran 77 and 90. Computer: Workstations. Operating system: Unix, GNU/Linux. Has the code been vectorized or parallelized?: Shared-memory parallelization can be used for most tasks. Classification: 7.3. Catalogue identifier of previous version: AECB_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 157 Nature of problem: Analysis of quantum-chemical

  17. New generation of docking programs: Supercomputer validation of force fields and quantum-chemical methods for docking.

    Science.gov (United States)

    Sulimov, Alexey V; Kutov, Danil C; Katkova, Ekaterina V; Ilin, Ivan S; Sulimov, Vladimir B

    2017-11-01

    Discovery of new inhibitors of the protein associated with a given disease is the initial and most important stage of the whole process of the rational development of new pharmaceutical substances. New inhibitors block the active site of the target protein and the disease is cured. Computer-aided molecular modeling can considerably increase effectiveness of new inhibitors development. Reliable predictions of the target protein inhibition by a small molecule, ligand, is defined by the accuracy of docking programs. Such programs position a ligand in the target protein and estimate the protein-ligand binding energy. Positioning accuracy of modern docking programs is satisfactory. However, the accuracy of binding energy calculations is too low to predict good inhibitors. For effective application of docking programs to new inhibitors development the accuracy of binding energy calculations should be higher than 1kcal/mol. Reasons of limited accuracy of modern docking programs are discussed. One of the most important aspects limiting this accuracy is imperfection of protein-ligand energy calculations. Results of supercomputer validation of several force fields and quantum-chemical methods for docking are presented. The validation was performed by quasi-docking as follows. First, the low energy minima spectra of 16 protein-ligand complexes were found by exhaustive minima search in the MMFF94 force field. Second, energies of the lowest 8192 minima are recalculated with CHARMM force field and PM6-D3H4X and PM7 quantum-chemical methods for each complex. The analysis of minima energies reveals the docking positioning accuracies of the PM7 and PM6-D3H4X quantum-chemical methods and the CHARMM force field are close to one another and they are better than the positioning accuracy of the MMFF94 force field. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Quantum chemical analysis of the electronic structure and Moessbauer spectra parameters for low spin cyanide- and pyridine-hemichromes

    International Nuclear Information System (INIS)

    Khleskov, V.I.; Kolpakov, E.V.; Smirnov, A.B.

    1992-01-01

    The work contains results of quantum-chemical calculations of electronic structure and Moessbauer spectra parameters for low spin S=1/2 hexa-coordinated ferri-porphyrin complexes with cyanide (CN) and pyridine (Py) as axial ligands. Theoretical results made it possible to explain experimentally observed regularity of anomalous quadrupole splitting decrease after substitution of Py-ligands by CN. Comparison of theoretical and experimental data indicated that 2 E g must be the ground state of investigated hemichromes. In this state unpaired electron symmetrically occupies d π -orbitals of Fe-ion. (orig.)

  19. Quantum chemical approach for condensed-phase thermochemistry (V): Development of rigid-body type harmonic solvation model

    Science.gov (United States)

    Tarumi, Moto; Nakai, Hiromi

    2018-05-01

    This letter proposes an approximate treatment of the harmonic solvation model (HSM) assuming the solute to be a rigid body (RB-HSM). The HSM method can appropriately estimate the Gibbs free energy for condensed phases even where an ideal gas model used by standard quantum chemical programs fails. The RB-HSM method eliminates calculations for intra-molecular vibrations in order to reduce the computational costs. Numerical assessments indicated that the RB-HSM method can evaluate entropies and internal energies with the same accuracy as the HSM method but with lower calculation costs.

  20. Predicting allergic contact dermatitis: a hierarchical structure activity relationship (SAR) approach to chemical classification using topological and quantum chemical descriptors

    Science.gov (United States)

    Basak, Subhash C.; Mills, Denise; Hawkins, Douglas M.

    2008-06-01

    A hierarchical classification study was carried out based on a set of 70 chemicals—35 which produce allergic contact dermatitis (ACD) and 35 which do not. This approach was implemented using a regular ridge regression computer code, followed by conversion of regression output to binary data values. The hierarchical descriptor classes used in the modeling include topostructural (TS), topochemical (TC), and quantum chemical (QC), all of which are based solely on chemical structure. The concordance, sensitivity, and specificity are reported. The model based on the TC descriptors was found to be the best, while the TS model was extremely poor.

  1. Combined friction force microscopy and quantum chemical investigation of the tribotronic response at the propylammonium nitrate-graphite interface.

    Science.gov (United States)

    Li, H; Atkin, R; Page, A J

    2015-06-28

    The energetic origins of the variation in friction with potential at the propylammonium nitrate-graphite interface are revealed using friction force microscopy (FFM) in combination with quantum chemical simulations. For boundary layer lubrication, as the FFM tip slides energy is dissipated via (1) boundary layer ions and (2) expulsion of near-surface ion layers from the space between the surface and advancing tip. Simulations reveal how changing the surface potential changes the ion composition of the boundary and near surface layer, which controls energy dissipation through both pathways, and thus the friction.

  2. Photocatalytic oxidation dynamics of acetone on TiO2: tight-binding quantum chemical molecular dynamics study

    International Nuclear Information System (INIS)

    Lv Chen; Wang Xiaojing; Agalya, Govindasamy; Koyama, Michihisa; Kubo, Momoji; Miyamoto, Akira

    2005-01-01

    The clarification of the excited states dynamics on TiO 2 surface is important subject for the design of the highly active photocatalysts. In the present study, we applied our novel tight-binding quantum chemical molecular dynamics method to the investigation on the photocatalytic oxidation dynamics of acetone by photogenerated OH radicals on the hydrated anatase TiO 2 surface. The elucidated photocatalytic reaction mechanism strongly supports the previous experimental proposal and finally the effectiveness of our new approach for the clarification of the photocatalytic reaction dynamics employing the large simulation model was confirmed

  3. Increasing Understanding of Public Problems and Policies. A Group Study of Four Topics in the Field of Extension Education.

    Science.gov (United States)

    Farm Foundation, Chicago, IL.

    The publication contains thirteen reports from the Twentieth National Agricultural Policy Conference held September 22-25, 1970, at Pokagon State Park, Angola, Indiana. The conference was designed to assist extension workers by broadening their perspective, understanding, and handling of the methodology of public affairs education. Four topics in…

  4. Structural, vibrational, electronic investigations and quantum chemical studies of 2-amino-4-methoxybenzothiazole

    Science.gov (United States)

    Arjunan, V.; Raj, Arushma; Santhanam, R.; Marchewka, M. K.; Mohan, S.

    2013-02-01

    Extensive vibrational investigations of 2-amino-4-methoxybenzothiazole have been carried out with FTIR and FT-Raman spectral techniques. The electronic structure of the molecule has been analysed by UV-Visible and NMR spectroscopies. The DFT studies were carried out with B3LYP and HF methods utilising 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets to determine the structural, thermodynamical, vibrational, electronic characteristics of the compound and also to understand the electronic and steric influence of the methoxy amino groups on the skeletal frequencies. The mixing of the fundamental modes was determined with the help of total energy distribution (TED). The energies of the frontier molecular orbitals have also been determined. The kinetic and thermodynamic stability and chemical hardness of the molecule have been determined. Complete NBO analysis was also carried out to find out the intramolecular electronic interactions and their stabilisation energy. 1H and 13C NMR chemical shifts and the electronic transitions of the molecule are also discussed.

  5. Structural, vibrational, electronic investigations and quantum chemical studies of 2-amino-4-methoxybenzothiazole.

    Science.gov (United States)

    Arjunan, V; Raj, Arushma; Santhanam, R; Marchewka, M K; Mohan, S

    2013-02-01

    Extensive vibrational investigations of 2-amino-4-methoxybenzothiazole have been carried out with FTIR and FT-Raman spectral techniques. The electronic structure of the molecule has been analysed by UV-Visible and NMR spectroscopies. The DFT studies were carried out with B3LYP and HF methods utilising 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets to determine the structural, thermodynamical, vibrational, electronic characteristics of the compound and also to understand the electronic and steric influence of the methoxy amino groups on the skeletal frequencies. The mixing of the fundamental modes was determined with the help of total energy distribution (TED). The energies of the frontier molecular orbitals have also been determined. The kinetic and thermodynamic stability and chemical hardness of the molecule have been determined. Complete NBO analysis was also carried out to find out the intramolecular electronic interactions and their stabilisation energy. (1)H and (13)C NMR chemical shifts and the electronic transitions of the molecule are also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Conformation of the azo bond and its influence on the molecular and crystal structures, IR and Raman spectra, and electron properties of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine - Quantum chemical DFT calculations

    Science.gov (United States)

    Michalski, J.; Bryndal, I.; Lorenc, J.; Hermanowicz, K.; Janczak, J.; Hanuza, J.

    2018-02-01

    The crystal and molecular structures of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine have been determined by X-ray diffraction and quantum chemical DFT calculations. The crystal is monoclinic, space group Cc (No. 9) with Z = 4 with the unit cell parameters: a = 12.083(7), b = 12.881(6), c = 8.134(3) Å and β = 97.09(5)°. The azo-bridge appears in the trans conformation in which C2-N2-N2‧-C1‧ torsion angle takes a value - 178.6(3)°, whereas the dihedral angle between the planes of the phenyl and pyridine rings is 3.5(2)°. The IR and Raman spectra measured in the temperature range 80-350 K and quantum chemical calculations with the use of B3LYP/6-311G(2d,2p) approach confirmed the trans configuration of the azo-bridge as the most stable energetically and allowed determination of the energy other virtual structures. The observed effects were used in the discussion of vibrational dynamics of the studied compound. The energy gap between cis and trans conformers equals to 1.054 eV (0.03873 Hartree). The electron absorption and emission spectra have been measured and analyzed on the basis of DFT calculations. The life time of the excited state is 12 μs and the Stokes shift is close to 5470 cm- 1.

  7. Safety margin evaluation concepts for plant Up rates and life extension. Results of the OECD/NEA/CSNI working group on Safety Margin Action Plan (SMAP)

    International Nuclear Information System (INIS)

    Belac, J

    2006-01-01

    This presentation summarizes results of the OECD/NEA/CSNI working group on Safety Margin Action Plan (SMAP) aimed to develop generalized safety margin concept and means of its quantification for the process of evaluating plant safety in the frame of plant life extension and power up rating activities to be used by OECD member countries. (author)

  8. Mechanisms of Innovation Diffusion under Information Abundance and Information Scarcity--On the Contribution of Social Networks in Group vs. Individual Extension Approaches in Semi-Arid Kenya

    Science.gov (United States)

    Darr, Dietrich; Pretzsch, Jurgen

    2008-01-01

    Purpose: The objective of this paper is to assess the effectiveness of innovation diffusion under group-oriented and individual-oriented extension. Current theoretical notions of innovation diffusion in social networks shall be briefly reviewed, and the concepts of "search" and "innovation" vis-a-vis "transfer" and…

  9. Quantum chemical analysis of binary and ternary ferromagnetic alloys; Quantenchemische Untersuchungen binaerer und ternaerer ferromagnetischer Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Yasemin Erika Charlotte

    2007-02-23

    In this work the electronic structures, densities of states, chemical bonding, magnetic exchange Parameters and Curie temperatures of binary and ternary ferromagnetic alloys are analyzed. The electronic structure of ferromagnetic MnAl has been calculated using density-functional techniques (TB-LMTO-ASA, FPLAPW) and quantum chemically analyzed by means of the crystal orbital Hamilton population analysis. The crystal structure of the ferromagnetic tetragonal MnAl may be understood to originate from the structure of nonmagnetic cubic MnAl with a CsCl motif through a two-step process. While the nonmagnetic cubic structure is stable against a structural deformation, antibonding Mn-Mn interactions at the Fermi level lead to spin polarization and the onset of magnetism, i.e., a symmetry reduction taking place solely in the electronic degrees of freedom, by that emptying antibonding Mn-Mn states. Residual antibonding Al--Al states can only be removed by a subsequent, energetically smaller structural deformation towards the tetragonal system. As a final result, homonuclear bonding is strengthened and heteronuclear bonding is weakened. Corresponding DFT calculations of the electronic structure as well as the calculation of the chemical bonding and the magnetic exchange interactions have been performed on the basis of LDA and GGA for a series of ferromagnetic full Heusler alloys of general formula Co2MnZ (Z=Ga,Si,Ge,Sn), Rh2MnZ (Z=Ge,Sn,Pb), Ni2MnZ (Z=Ga,In,Sn), Pd2MnZ (Z=Sn,Sb) and Cu2MnZ (Z=Al,In,Sn). The connection between the electronic spectra and the magnetic interactions have been studied. Correlations between the chemical bondings in Heusler alloys derived from COHP analysis and magnetic phenomena are obvious, and different mechanisms leading to spin polarization and ferromagnetism are derived. The band dependence of the exchange parameters, their dependence on volume and valence electron concentration have been thoroughly analyzed within the Green function technique

  10. Prediction of radical scavenging activities of anthocyanins applying adaptive neuro-fuzzy inference system (ANFIS) with quantum chemical descriptors.

    Science.gov (United States)

    Jhin, Changho; Hwang, Keum Taek

    2014-08-22

    Radical scavenging activity of anthocyanins is well known, but only a few studies have been conducted by quantum chemical approach. The adaptive neuro-fuzzy inference system (ANFIS) is an effective technique for solving problems with uncertainty. The purpose of this study was to construct and evaluate quantitative structure-activity relationship (QSAR) models for predicting radical scavenging activities of anthocyanins with good prediction efficiency. ANFIS-applied QSAR models were developed by using quantum chemical descriptors of anthocyanins calculated by semi-empirical PM6 and PM7 methods. Electron affinity (A) and electronegativity (χ) of flavylium cation, and ionization potential (I) of quinoidal base were significantly correlated with radical scavenging activities of anthocyanins. These descriptors were used as independent variables for QSAR models. ANFIS models with two triangular-shaped input fuzzy functions for each independent variable were constructed and optimized by 100 learning epochs. The constructed models using descriptors calculated by both PM6 and PM7 had good prediction efficiency with Q-square of 0.82 and 0.86, respectively.

  11. Prediction of Radical Scavenging Activities of Anthocyanins Applying Adaptive Neuro-Fuzzy Inference System (ANFIS with Quantum Chemical Descriptors

    Directory of Open Access Journals (Sweden)

    Changho Jhin

    2014-08-01

    Full Text Available Radical scavenging activity of anthocyanins is well known, but only a few studies have been conducted by quantum chemical approach. The adaptive neuro-fuzzy inference system (ANFIS is an effective technique for solving problems with uncertainty. The purpose of this study was to construct and evaluate quantitative structure-activity relationship (QSAR models for predicting radical scavenging activities of anthocyanins with good prediction efficiency. ANFIS-applied QSAR models were developed by using quantum chemical descriptors of anthocyanins calculated by semi-empirical PM6 and PM7 methods. Electron affinity (A and electronegativity (χ of flavylium cation, and ionization potential (I of quinoidal base were significantly correlated with radical scavenging activities of anthocyanins. These descriptors were used as independent variables for QSAR models. ANFIS models with two triangular-shaped input fuzzy functions for each independent variable were constructed and optimized by 100 learning epochs. The constructed models using descriptors calculated by both PM6 and PM7 had good prediction efficiency with Q-square of 0.82 and 0.86, respectively.

  12. In situ synthesis, electrochemical and quantum chemical analysis of an amino acid-derived ionic liquid inhibitor for corrosion protection of mild steel in 1M HCl solution

    International Nuclear Information System (INIS)

    Kowsari, E.; Arman, S.Y.; Shahini, M.H.; Zandi, H.; Ehsani, A.; Naderi, R.; PourghasemiHanza, A.; Mehdipour, M.

    2016-01-01

    Highlights: • Electrochemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Quantum chemical analysis of effectiveness of an amino acid-derived ionic liquid inhibitor. • Finding correlation between electrochemical analysis and quantum chemical analysis. - Abstract: In this study, an amino acid-derived ionic liquid inhibitor, namely tetra-n-butyl ammonium methioninate, was synthesized and the role this inhibitor for corrosion protection of mild steel exposed to 1.0 M HCl was investigated using electrochemical, quantum and surface analysis. By taking advantage of potentiodynamic polarization, the inhibitory action of tetra-n-butyl ammonium methioninate was found to be mainly mixed-type with dominant anodic inhibition. The effectiveness of the inhibitor was also indicated using electrochemical impedance spectroscopy (EIS). Moreover, to provide further insight into the mechanism of inhibition, electrochemical noise (EN) and quantum chemical calculations of the inhibitor were performed.

  13. AER working group A on improvement extension and validation of parametrized few-group libraries for VVER-440 and VVER-1000

    International Nuclear Information System (INIS)

    Svarny, J.

    1998-01-01

    The AER Working Groups A and B held its sixth meeting at SKODA JS, Plzen in April 28 and 29, 1998. There were altogether 13 participants from 6 member organizations. The list of participants and the list of papers are attached. Main topics of the meeting were: A few-group cross-section library preparation methodology (standard few-group libraries, kinetics parameters, SPND signal interpretation parametrization) and its validation; Participation on intercomparisons of spectral codes (spectral codes benchmark); of kinetics parameters calculations (kinetics parameters benchmark). (author)

  14. Atomic Energy Research working group a on improvement extension and validation of parametrized FEW-group libraries for WWER-440 and WWER-1000

    International Nuclear Information System (INIS)

    Svarny, J.

    1998-01-01

    The AER Working Groups A and B held its sixth meeting at SKODA JS, Plzen in April 28 and 29, 1998. There were altogether 13 participants from 6 member organizations. The list of participants and the list of papers are attached. (Author)

  15. Extension and improvement of the FENDL library for fusion applications (FENDL-2). Report of an IAEA advisory group meeting

    International Nuclear Information System (INIS)

    Herman, M.; Pashchenko, A.B.

    1997-09-01

    The present report contains the summary of the IAEA Advisory Meeting on Extension and Improvement of the Fusion Evaluated Nuclear Data Library (FENDL), organized by IAEA Nuclear Data Section and held in IAEA headquarters in Vienna from 3 to 7 March 1997. The FENDL library is a comprehensive collection of high-quality nuclear data, selected from the various existing national data libraries, covering the necessary input for physics and engineering studies of the material development, design, operation and safety of ITER and other fusion devices. The library has undergone an intensive testing and validation against integral benchmarks. The main scope of the Meeting was to discuss recent developments within FENDL project, review new evaluations to be included in the library, and decide on the release of the second version of the library (FENDL-2.0). During the meeting it was demonstrated that the FENDL-2.0 library shows a net improvement over the preceding FENDL-1. The release of the Library was authorized with the exception of the general purpose field FENDL/E-2.0 and its processed form, which is scheduled at the end of 1997. (author)

  16. SUCCESS AND PITFALLS OF THE DIELECTRIC CONTINUUM MODEL IN QUANTUM-CHEMICAL CALCULATIONS

    NARCIS (Netherlands)

    DEVRIES, AH; VANDUIJNEN, PT; JUFFER, AH

    1993-01-01

    Recently we presented an extension of the direct reaction field (DRF) method, in which a quantum system and a set of point charges and interacting polarizabilities are embedded in a continuum that is characterized by a dielectric constant epsilon and a finite ionic strength. The reaction field of

  17. In Vivo Anti-Leukemia, Quantum Chemical Calculations and ADMET Investigations of Some Quaternary and Isothiouronium Surfactants

    Directory of Open Access Journals (Sweden)

    Ahmed A. El-Henawy

    2013-04-01

    Full Text Available Anti-leukemia screening of previously prepared isothiouronium and quaternary salts was performed, and some salts exhibited promising activity as anticancer agents. Quantum chemical calculations were utilized to explore the electronic structure and stability of these compounds. Computational studies have been carried out at the PM3 semiempirical molecular orbitals level, to establish the HOMO-LUMO, IP and ESP mapping of these compounds. The ADMET properties were also studied to gain a clear view of the potential oral bioavailability of these compounds. The surface properties calculated included critical micelle concentration (CMC, maximum surface excess (Γmax, minimum surface area (Amin, free energy of micellization (ΔGomic and adsorption (ΔGoads.

  18. A quantum chemical analysis of Zn and Sb doping and co-doping in SnO2

    Directory of Open Access Journals (Sweden)

    Luis Villamagua

    2017-10-01

    Full Text Available This work presents a quantum chemical study of Zn and Sb doping and co-doping in SnO2 carried out by a DFT+U method. The analysis has been developed by introducing three different modifications in the otherwise pure SnO2 system. In the first place, an oxygen vacancy was introduced within the crystal. Following, such a system was doped (separately by Zn or Sb impurities. Finally, the best energetic positions for both Zn and Sb atoms were simultaneously introduced within the lattice. Results of the simulations show that the confined charge that appeared due to the introduction of the oxygen vacancy interacts with the dopants atoms, being this interaction mostly responsible of the observed effects, i.e., EG shrinkage, F-centers formations, and magnetic momentum rise.

  19. Combinatorial computational chemistry approach of tight-binding quantum chemical molecular dynamics method to the design of the automotive catalysts

    International Nuclear Information System (INIS)

    Ito, Yuki; Jung, Changho; Luo, Yi; Koyama, Michihisa; Endou, Akira; Kubo, Momoji; Imamura, Akira; Miyamoto, Akira

    2006-01-01

    Recently, we have developed a new tight-binding quantum chemical molecular dynamics program 'Colors' for combinatorial computational chemistry approach. This methodology is based on our original tight-binding approximation and realized over 5000 times acceleration compared to the conventional first-principles molecular dynamics method. In the present study, we applied our new program to the simulations on various realistic large-scale models of the automotive three-way catalysts, ultrafine Pt particle/CeO 2 (111) support. Significant electron transfer from the Pt particle to the CeO 2 (111) surface was observed and it was found to strongly depend on the size of the Pt particle. Furthermore, our simulation results suggest that the reduction of the Ce atom due to the electron transfer from the Pt particle to the CeO 2 surface is a main reason for the strong interaction of the Pt particle and CeO 2 (111) support

  20. Quantitative structure-activation barrier relationship modeling for Diels-Alder ligations utilizing quantum chemical structural descriptors.

    Science.gov (United States)

    Nandi, Sisir; Monesi, Alessandro; Drgan, Viktor; Merzel, Franci; Novič, Marjana

    2013-10-30

    In the present study, we show the correlation of quantum chemical structural descriptors with the activation barriers of the Diels-Alder ligations. A set of 72 non-catalysed Diels-Alder reactions were subjected to quantitative structure-activation barrier relationship (QSABR) under the framework of theoretical quantum chemical descriptors calculated solely from the structures of diene and dienophile reactants. Experimental activation barrier data were obtained from literature. Descriptors were computed using Hartree-Fock theory using 6-31G(d) basis set as implemented in Gaussian 09 software. Variable selection and model development were carried out by stepwise multiple linear regression methodology. Predictive performance of the quantitative structure-activation barrier relationship (QSABR) model was assessed by training and test set concept and by calculating leave-one-out cross-validated Q2 and predictive R2 values. The QSABR model can explain and predict 86.5% and 80% of the variances, respectively, in the activation energy barrier training data. Alternatively, a neural network model based on back propagation of errors was developed to assess the nonlinearity of the sought correlations between theoretical descriptors and experimental reaction barriers. A reasonable predictability for the activation barrier of the test set reactions was obtained, which enabled an exploration and interpretation of the significant variables responsible for Diels-Alder interaction between dienes and dienophiles. Thus, studies in the direction of QSABR modelling that provide efficient and fast prediction of activation barriers of the Diels-Alder reactions turn out to be a meaningful alternative to transition state theory based computation.

  1. Extension of Mediema's Macroscopic Atom Model to the Elements of Group 16 (O, S, Se, Te ,Po)

    CERN Document Server

    Neuhausen, J

    2003-01-01

    A consistent set of Miedema-parameters has been developed for the elements of the chalcogen group (Group 16 of the periodic table of the elements: 0, S, Se, Te, Po) from ab-initio quantum-mechanical calculations as weIl as empirical correlations. Using this parameter set thermochemical properties such as enthalpies of formation of solid metal chalcogenides, partial molar enthalpies of solution of chalcogens in liquid and solid metaIs, partial molar enthalpies of evaporation of the chalcogens from liquid metal solution into the monoatomic gaseous state, partial molar enthalpies of adsorption of chalcogenides on metal surfaces at zero coverage and partial molar enthalpies of segregation of the chalcogens in trace amounts within solid metal matrices have been calculated. These properties are compared with available experimental data and discussed with an emphasis on the periodic behaviour of the elements. The model calculations show that a description of the thermochemical properties of the chalcogens using the ...

  2. Quantum chemical estimation of sorption/desorption of H{sub 2} and H{sub 2}O (gas) at the plasma-wall interface

    Energy Technology Data Exchange (ETDEWEB)

    Nagasaki, Shinya; Tsushima, Satoru; Tanaka, Masataka; Umemura, Yasuhiro [Tokyo Univ. (Japan). Faculty of Engineering

    1996-10-01

    By using MOPAC Code, we estimated the charge density of SiO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2} metal oxide. We could find that the such quantum chemical calculation is a fruitful tool for understanding the plasma-wall interactions from the microscopic point of view. (author)

  3. Exploring the Structure of a DNA Hairpin with the Help of NMR Spin-Spin Coupling Constants: An Experimental and Quantum Chemical Investigation

    Czech Academy of Sciences Publication Activity Database

    Sychrovský, Vladimír; Vacek, Jaroslav; Hobza, Pavel; Žídek, L.; Sklenář, V.; Cremer, D.

    2002-01-01

    Roč. 106, - (2002), s. 10242-10250 ISSN 1089-5639 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : DNA * help of NMR spin-spin coupling constants * quantum chemical investigation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.765, year: 2002

  4. Distribution of electron density and internal rotation in phospha-alkenes according to data from quantum-chemical calculations by the MNDO method

    International Nuclear Information System (INIS)

    Boldeskul, I.E.; Pen'kovskii, V.V.; Povolotskii, M.I.

    1988-01-01

    A quantum-chemical investigation of the characteristics of the phosphorus-carbon bond and the internal rotation around it in phospha-alkenes has been carried out in the MNDO approximation. The results of the calculation have been compared with experimental dynamic 1 H NMR data

  5. Extension of Mediema's Macroscopic Atom Model to the Elements of Group 16 (O, S, Se, Te ,Po)

    Energy Technology Data Exchange (ETDEWEB)

    Neuhausen, J.; Eichler, B

    2003-09-01

    A consistent set of Miedema-parameters has been developed for the elements of the chalcogen group (Group 16 of the periodic table of the elements: 0, S, Se, Te, Po) from ab-initio quantum-mechanical calculations as weIl as empirical correlations. Using this parameter set thermochemical properties such as enthalpies of formation of solid metal chalcogenides, partial molar enthalpies of solution of chalcogens in liquid and solid metaIs, partial molar enthalpies of evaporation of the chalcogens from liquid metal solution into the monoatomic gaseous state, partial molar enthalpies of adsorption of chalcogenides on metal surfaces at zero coverage and partial molar enthalpies of segregation of the chalcogens in trace amounts within solid metal matrices have been calculated. These properties are compared with available experimental data and discussed with an emphasis on the periodic behaviour of the elements. The model calculations show that a description of the thermochemical properties of the chalcogens using the semi-empirical Miedema approach is possible. The calculated properties can serve as a basis for the prediction of the chemical interactions for metal-chalcogen combinations that have not been studied experimentally so far. (author)

  6. Extension of Mediema's Macroscopic Atom Model to the Elements of Group 16 (O, S, Se, Te ,Po)

    International Nuclear Information System (INIS)

    Neuhausen, J.; Eichler, B.

    2003-09-01

    A consistent set of Miedema-parameters has been developed for the elements of the chalcogen group (Group 16 of the periodic table of the elements: 0, S, Se, Te, Po) from ab-initio quantum-mechanical calculations as weIl as empirical correlations. Using this parameter set thermochemical properties such as enthalpies of formation of solid metal chalcogenides, partial molar enthalpies of solution of chalcogens in liquid and solid metaIs, partial molar enthalpies of evaporation of the chalcogens from liquid metal solution into the monoatomic gaseous state, partial molar enthalpies of adsorption of chalcogenides on metal surfaces at zero coverage and partial molar enthalpies of segregation of the chalcogens in trace amounts within solid metal matrices have been calculated. These properties are compared with available experimental data and discussed with an emphasis on the periodic behaviour of the elements. The model calculations show that a description of the thermochemical properties of the chalcogens using the semi-empirical Miedema approach is possible. The calculated properties can serve as a basis for the prediction of the chemical interactions for metal-chalcogen combinations that have not been studied experimentally so far. (author)

  7. Quantum chemical calculations and experimental investigations on 2-aminobenzoic acid-cyclodiphosph(V)azane derivative and its homo-binuclear Cu(II) complex

    Science.gov (United States)

    El-Gogary, Tarek M.; Alaghaz, Abdel-Nasser M. A.; Ammar, Reda A. A.

    2012-03-01

    A novel 2-aminobenzoic acid-cyclodiphosph(V)azane ligand H4L and its homo-binuclear Cu(II) complex of the type [Cu2L(H2O)2].2.5 H2O in which L is 1,3-di(-o-pyridyl)-2,4-(dioxo)-2',4'-bis-(2-iminobenzoic acid) cyclodiphosph(V)azane, were synthesized and characterized by different physical techniques. Infrared spectra of the complex indicate deprotonation and coordination of the imine NH and carboxyl COOH groups. It also confirms that nitrogen atom of the pyridine ring contribute to the complexation. Electronic spectra and magnetic susceptibility measurements reveal square-planar geometry for the Cu(II) complex. The elemental analyses and thermogravimetric results have justified the [Cu2L(H2O)2]·2.5H2O composition of the complex. Quantum chemical calculations were utilized to explore the electronic structure and stability of the H4L as well as the binuclear Cu(II) complex. Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of H4L and its binuclear Cu(II) complex. Different tautomers and geometrical isomers of the ligand were optimized at the ab initio DFT level. Simulated IR frequencies were scaled and compared with that experimentally measured. TD-DFT method was used to compute the UV-VIS spectra which show good agreement with measured electronic spectra.

  8. A quantum chemical study of the reactivity of acetaminophen (paracetamol) toxic metabolite N-acetyl-p-benzoquinone imine with deoxyguanosine and glutathione.

    Science.gov (United States)

    Klopčič, Ivana; Poberžnik, Matic; Mavri, Janez; Dolenc, Marija Sollner

    2015-12-05

    Acetaminophen (APAP) forms some reactive metabolites that can react with DNA. APAP is a potentially genotoxic drug and is classified as a Group 3 drug according to International Agency for Research on Cancer (IARC). One of the possible mechanisms of APAP genotoxicity after long term of use is that its reactive quinone imine (QI) metabolite of acetaminophen (NAPQI), can chemically react with DNA after glutathione (GSH) depletion. A quantum chemical study of the reactions between the NAPQI and deoxyguanosine (dG) or GSH was performed. Activation energies (ΔG(ǂ)) for the reactions associated with the 1, 4-Michael addition were calculated on the M062X/6-311++G (d,p) level of theory. We modeled the reaction with dG as a multi-step process. The first step is rate-limiting (ΔG(ǂ) = 26.7 kcal/mol) and consists of formation of a C-N bond between the C3 atom of the QI moiety and the N7 atom of dG. The second step involves proton transfer from the C3 moiety to the nitrogen atom of the QI with ΔG(ǂ) of 13.8 kcal/mol. The depurination reaction that follows has a ΔG(ǂ) of 25.7 kcal/mol. The calculated ΔG(ǂ) for the nucleophilic attack of the deprotonated S atom of GSH on the C3 atom of the NAPQI is 12.9 kcal/mol. Therefore, the QI will react with GSH much faster than with DNA. Our study gives mechanistic insight into the genotoxicity of the APAP metabolite and will be useful for estimating the genotoxic potential of existing drugs with a QI moiety. Our results show that clinical application of APAP is safe, while in the case of severely depleted GSH levels APAP should be administered with caution. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Rotational Spectrum, Conformational Composition, and Quantum Chemical Calculations of Cyanomethyl Formate (HC(O)OCH2C≡N), a Compound of Potential Astrochemical Interest.

    Science.gov (United States)

    Samdal, Svein; Møllendal, Harald; Carles, Sophie

    2015-08-27

    The rotational spectrum of cyanomethyl formate (HC(O)OCH2C≡N) has been recorded in the 12–123 GHz spectral range. The spectra of two conformers were assigned. The rotamer denoted I has a symmetry plane and two out-of plane hydrogen atoms belonging to the cyanomethyl (CH2CN) moiety. In the conformer called II, the cyanomethyl group is rotated 80.3° out of this plane. Conformer I has an energy that is 1.4(6) kJ/mol lower than the energy of II according to relative intensity measurements. A large number of rotational transitions have been assigned for the ground and vibrationally excited states of the two conformers and accurate spectroscopic constants have been obtained. These constants should predict frequencies of transitions outside the investigated spectral range with a very high degree of precision. It is suggested that cyanomethyl formate is a potential interstellar compound. This suggestion is based on the fact that its congener methyl formate (HC(O)OCH3) exists across a large variety of interstellar environments and the fact that cyanides are very prevalent in the Universe. The experimental work has been augmented by high-level quantum chemical calculations. The CCSD/cc-pVQZ calculations are found to predict structures of the two forms that are very close to the Born–Oppenheimer equilibrium structures. MP2/cc-pVTZ predictions of several vibration–rotation interaction constants were generally found to be rather inaccurate. A gas-phase reaction between methyl formate and the cyanomethyl radical CH2CN to produce a hydrogen atom and cyanomethyl formate was mimicked using MP2/cc-pVTZ calculations. It was found that this reaction is not favored thermodynamically. It is also conjectured that the possible formation of cyanomethyl formate might be catalyzed and take place on interstellar particles.

  10. Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde.

    Science.gov (United States)

    Abbas, Ashgar; Gökce, Halil; Bahçeli, Semiha

    2016-01-05

    In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, (1)H and (13)C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Semiempirical Quantum-Chemical Orthogonalization-Corrected Methods: Benchmarks for Ground-State Properties.

    Science.gov (United States)

    Dral, Pavlo O; Wu, Xin; Spörkel, Lasse; Koslowski, Axel; Thiel, Walter

    2016-03-08

    The semiempirical orthogonalization-corrected OMx methods (OM1, OM2, and OM3) go beyond the standard MNDO model by including additional interactions in the electronic structure calculation. When augmented with empirical dispersion corrections, the resulting OMx-Dn approaches offer a fast and robust treatment of noncovalent interactions. Here we evaluate the performance of the OMx and OMx-Dn methods for a variety of ground-state properties using a large and diverse collection of benchmark sets from the literature, with a total of 13035 original and derived reference data. Extensive comparisons are made with the results from established semiempirical methods (MNDO, AM1, PM3, PM6, and PM7) that also use the NDDO (neglect of diatomic differential overlap) integral approximation. Statistical evaluations show that the OMx and OMx-Dn methods outperform the other methods for most of the benchmark sets.

  12. Quantum Chemical and Physicochemical Studies of Oximes (Prophylactics against and Reactivators of Phosphorylated AChE).

    Science.gov (United States)

    1984-10-25

    crystal structure of nicotinic acid ,. and we used the ether bridge from the crystal structure of dimethyl ether. We are investigating various rotamers...observations were made: - The titration curve (after the subtraction of the blank curve) shows only one titrable group, i.e. the oxime moiety. - The...subtraction of the blank curve, shows two titrable groups, i.e. the two oxime moieties. The results are as follows: Temperature Conditions PKa pK2

  13. Hydrolysis of aspartic acid phosphoramidate nucleotides: a comparative quantum chemical study.

    Science.gov (United States)

    Michielssens, Servaas; Tien Trung, Nguyen; Froeyen, Matheus; Herdewijn, Piet; Tho Nguyen, Minh; Ceulemans, Arnout

    2009-09-07

    L-Aspartic acid has recently been found to be a good leaving group during HIV reverse transcriptase catalyzed incorporation of deoxyadenosine monophosphate (dAMP) in DNA. This showed that L-Asp is a good mimic for the pyrophosphate moiety of deoxyadenosine triphosphate. The present work explores the thermochemistry and mechanism for hydrolysis of several models for L-aspartic-dAMP using B3LYP/DGDZVP, MP2/6-311++G** and G3MP2 level of theory. The effect of the new compound is gradually investigated: starting from a simple methyl amine leaving group up to the aspartic acid leaving group. The enzymatic environment was mimicked by involving two Mg(2+) ions and some important active site residues in the reaction. All reactions are compared to the corresponding O-coupled leaving group, which is methanol for methyl amine and malic acid for aspartic acid. With methyl amine as a leaving group a tautomeric associative or tautomeric dissociative mechanism is preferred and the barrier is lower than the comparable mechanism with methanol as a leaving group. The calculations on the aspartic acid in the enzymatic environment show that qualitatively the mechanism is the same as for triphosphate but the barrier for hydrolysis by the associative mechanism is higher for L-aspartic-dAMP than for L-malic-dAMP and pyrophosphate.

  14. Information about AER WG a on improvement, extension and validation of parametrized few-group libraries for VVER 440 and VVER 1000

    International Nuclear Information System (INIS)

    Mikolas, P.

    2009-01-01

    Joint AER Working Group A on 'Improvement, extension and validation of parameterized few-group libraries for VVER-440 and VVER-1000' and AER Working group B on 'Core design' eighteenth meeting was hosted by Skoda JS a.s. in Plzen (Czech Republic) during the period of 4 to 6 May 2009. There were present altogether 16 participants from 6 member organizations and 13 presentations were read. Objectives of the meeting of WG A are: Issues connected with spectral calculations and few-groups libraries preparation, their accuracy and validation. Presentations were devoted to some aspects of few group libraries preparations and to the benchmark dealing with VVER-440 follower modeling in calculations. Gy. Hegyi gave some new information about NURESIM-NURISP EU project (ZR-6), R. Zajac spoke about the development of data libraries for codes BIPR-7 and PERMAK, P. Darilek compared FA's with Gd during burning process and Yu. Bilodid described further development of plutonium-based burnup history modeling in DYN3D burnup calculations. G. Hordosy presented results of control rod follower induced local power peaking computational benchmark and J. Svarny described Monte Carlo VVER-440 control rod follower benchmark computations. Future activities are also shortly described in the end of the paper. (author)

  15. Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor.

    Science.gov (United States)

    Kubo, M; Odai, K; Sugimoto, T; Ito, E

    2001-06-01

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485. We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

  16. Syntheses, structural elucidation, thermal properties, theoretical quantum chemical studies (DFT and biological studies of barbituric–hydrazone complexes

    Directory of Open Access Journals (Sweden)

    Amina A. Soayed

    2015-03-01

    Full Text Available Condensation of barbituric acid with hydrazine hydrate yielded barbiturichydrazone (L which was characterized using IR, 1H NMR and mass spectra. The Co(II, Ni(II and Cu(II complexes derived from this ligand have been synthesized and structurally characterized by elemental analyses, spectroscopic methods (IR, UV–Vis and ESR and thermal analyses (TGA, DTG and DTA and the structures were further elucidated using quantum chemical density functional theory. Complexes of L were found to have the ML.nH2O stoichiometry with either tetrahedral or octahedral geometry. The ESR data showed the Cu(II complex to be in a tetragonal geometry. Theoretical investigation of the electronic structure of metal complexes at the TD-DFT/B3LYP level of theory has been carried out and discussed. The fundamental vibrational wavenumbers were calculated and a good agreement between observed and scaled calculated wavenumbers was achieved. Thermal studies were performed to deduce the stabilities of the ligand and complexes. Thermodynamic parameters, such as the order of reactions (n, activation energy ΔE∗, enthalpy of reaction ΔH∗ and entropy ΔS∗ were calculated from DTA curves using Horowitz–Metzger method. The ligand L and its complexes have been screened for their antifungal and antibacterial activities and were found to possess better biological activities compared to those of unsubstituted barbituric acid complexes.

  17. Estimation of strength in different extra Watson-Crick hydrogen bonds in DNA double helices through quantum chemical studies.

    Science.gov (United States)

    Bandyopadhyay, D; Bhattacharyya, D

    2006-10-15

    It was shown earlier, from database analysis, model building studies, and molecular dynamics simulations that formation of cross-strand bifurcated or Extra Watson-Crick hydrogen (EWC) bonds between successive base pairs may lead to extra rigidity to DNA double helices of certain sequences. The strengths of these hydrogen bonds are debatable, however, as they do not have standard linear geometry criterion. We have therefore carried out detailed ab initio quantum chemical studies using RHF/6-31G(2d,2p) and B3LYP/6-31G(2p,2d) basis sets to determine strengths of several bent hydrogen bonds with different donor and acceptors. Interaction energy calculations, corrected for the basis set superposition errors, suggest that N-H...O type bent EWC hydrogen bonds are possible along same strands or across the strands between successive base pairs, leading to significant stability (ca. 4-9 kcal/mol). The N-H...N and C-H...O type interactions, however, are not so stabilizing. Hence, consideration of EWC N-H...O H-bonds can lead to a better understanding of DNA sequence directed structural features. Copyright (c) 2006 Wiley Periodicals, Inc.

  18. Conformational analysis, spectroscopic, structure-activity relations and quantum chemical simulation studies of 4-(trifluoromethyl)benzylamine

    Science.gov (United States)

    Arjunan, V.; Devi, L.; Mohan, S.

    2018-05-01

    The FT-IR and FT-Raman spectra of 4-trifluoromethylbenzylamine (TFMBA) have been recorded in the range 4000-450 and 4000-100 cm-1 respectively. The conformational analysis of the compound has been carried out to attain stable geometry of the compound. The complete vibrational assignment and analysis of the fundamental modes of the compound are carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The experimental vibrational frequencies are compared with the wavenumbers obtained theoretically from the B3LYP gradient calculations employing the standard high level 6-311++G** and cc-pVTZ basis sets for the optimised geometry of the compound. The structural parameters, thermodynamic properties and vibrational frequencies of the normal modes obtained from the B3LYP methods are in good agreement with the experimental data. The 1H (400 MHz; CDCl3) and 13C (100 MHz; CDCl3) nuclear magnetic resonance (NMR) spectra were also recorded. The electronic properties, highest occupied molecular orbital and lowest unoccupied molecular orbital energies are measured by DFT approach. The charges of the atoms by natural bond orbital (NBO) analysis are determined by B3LYP/cc-pVTZ method. The structure-chemical reactivity relations of the compound are determined through chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors by conceptual DFT methods.

  19. Elucidating Direct Photolysis Mechanisms of Different Dissociation Species of Norfloxacin in Water and Mg2+ Effects by Quantum Chemical Calculations.

    Science.gov (United States)

    Wang, Se; Wang, Zhuang

    2017-11-11

    The study of pollution due to combined antibiotics and metals is urgently needed. Photochemical processes are an important transformation pathway for antibiotics in the environment. The mechanisms underlying the effects of metal-ion complexation on the aquatic photochemical transformation of antibiotics in different dissociation forms are crucial problems in science, and beg solutions. Herein, we investigated the mechanisms of direct photolysis of norfloxacin (NOR) in different dissociation forms in water and metal ion Mg 2+ effects using quantum chemical calculations. Results show that different dissociation forms of NOR had different maximum electronic absorbance wavelengths (NOR 2+ direct photolysis pathways were de-ethylation (N7-C8 bond cleavage) and decarboxylation (C2-C5 bond cleavage). Furthermore, the presence of Mg 2+ changed the order of the wavelength at maximum electronic absorbance (NOR⁺-Mg 2+ direct photolysis of NOR⁰, NOR⁺, and NOR 2+ . The calculated TS results indicated that the presence of Mg 2+ increased E a for most direct photolysis pathways of NOR, while it decreased E a for some direct photolysis pathways such as the loss of the piperazine ring and the damage of the piperazine ring of NOR⁰ and the defluorination of NOR⁺.

  20. Diversion of the melanin synthetic pathway by dopamine product scavengers: A quantum chemical modeling of the reaction mechanisms

    Directory of Open Access Journals (Sweden)

    T. B. Demissie

    2017-01-01

    Full Text Available We report the stability and reactivity of the oxidation products as well as L-cysteine and N-acetylcysteine adducts of dopamine studied using quantum chemical calculations. The overall reactions studied were subdivided into four reaction channels. The first reaction channel is the oxidation of dopamine to form dopaminoquinone. The second reaction channel leads to melanin formation through subsequent reactions. The third and fourth reaction channels are reactions leading to the formation of dopaminoquinone adducts which are aimed to divert the synthesis of melanin. The results indicate that L-cysteine and N-acetylcysteine undergo chemical reactions mainly at C5 position of dopaminoquinone. The analyses of the thermodynamic energies indicate that L-cysteine and N-acetylcysteine covalently bind to dopaminoquinone by competing with the internal cyclization reaction of dopaminoquinone which leads to the synthesis of melanin. The analysis of the results, based on the reaction free energies, is also supported by the investigation of the natural bond orbitals of the reactants and products.

  1. Influence of N-Oxide Introduction on the Stability of Nitrogen-Rich Heteroaromatic Rings: A Quantum Chemical Study.

    Science.gov (United States)

    Yuan, Jia; Long, Xinping; Zhang, Chaoyang

    2016-12-01

    N-Oxidization is an important strategy for enhancing the density and energy of energetic materials. Nevertheless, the influence of N + -O - introduction on molecular stability remains relatively unknown. Thus, the present work comprehensively studied 102 basic N-rich ring structures, including azoles, furazans, and azines, as well as their N-oxides by quantum chemical calculations. The introduction of N + -O - weakens molecular stability in most cases because the process elongates chemical bonds, decreases ring aromaticity, narrows the gaps between the highest occupied and lowest unoccupied molecular orbitals, and increases the photochemical reactivity. Besides, the easy H transfer to the neighboring O atom, which forms a N-OH isomer in azoles, renders the stabilization by N-oxide introduction ineffective. However, N-oxide introduction can enhance the molecular stability of 1,2,3,4-tetrazine-1,3-dioxide and tetrazino-tetrazine 1,3,6,8-tetraoxide by promoting σ-π separation and relieving lone-pair repulsion. Moreover, the alternate arrangement of positive and negative charges is another factor stabilizing the 1,2,3,4-tetrazine ring by 1,3-dioxidation. Finally, we assess the accessibility of N-oxidized azoles and azines by regarding N 2 O and H 2 O 2 as oxidizers. We find that all the oxidations were exothermic, thermodynamically spontaneous, and kinetically feasible. After an overall evaluation, we propose 19 N-oxides as basic structures for high-energy materials with considerable stability.

  2. The molecular structure of 4-methylpyridine-N-oxide: Gas-phase electron diffraction and quantum chemical calculations

    Science.gov (United States)

    Belova, Natalya V.; Girichev, Georgiy V.; Kotova, Vitaliya E.; Korolkova, Kseniya A.; Trang, Nguyen Hoang

    2018-03-01

    The molecular structure of 4-methylpiridine-N-oxide, 4-MePyO, has been studied by gas-phase electron diffraction monitored by mass spectrometry (GED/MS) and quantum chemical (DFT) calculations. Both, quantum chemistry and GED analyses resulted in CS molecular symmetry with the planar pyridine ring. Obtained molecular parameters confirm the hyperconjugation in the pyridine ring and the sp2 hybridization concept of the nitrogen and carbon atoms in the ring. The experimental geometric parameters are in a good agreement with the parameters for non-substituted N-oxide and reproduced very closely by DFT calculations. The presence of the electron-donating CH3 substituent in 4-MePyO leads to a decrease of the ipso-angle and to an increase of r(N→O) in comparison with the non-substituted PyO. Electron density distribution analysis has been performed in terms of natural bond orbitals (NBO) scheme. The nature of the semipolar N→O bond is discussed.

  3. Quantum chemical and thermodynamic calculations of fulvic and humic copper complexes in reactions of malachite and azurite formation

    International Nuclear Information System (INIS)

    Fomin, Vitaliy N.; Gogol, Daniil B.; Rozhkovoy, Ivan E.; Ponomarev, Dmitriy L.

    2017-01-01

    This article provides a thermodynamic evaluation of the reactions of humic and fulvic acids in the process of malachite and azurite mineralogenesis. Semi-empirical methods AM/1, MNDO, PM3, PM5, PM6 and PM7 were used to compute the heat of formation, enthalpy and entropy for thermodynamic calculations of the reactions performed on the basis of Hess's law. It is shown that methods PM6 and PM7 in the MOPAC software package provide good compliance with experimental and calculated heats of formation for copper complexes and alkaline earth metal complexes with organic acids. It is found that the malachite and azurite formation processes involving humus complexing substances are thermodynamically possible. - Highlights: • Copper and alkali-earth metal complexes with humic and fulvic acids are considered. • Quantum chemical calculation of thermodynamics for the structures was performed. • Semi-empirical methods PM6 and PM7 provide best correlation for the properties. • Parameters of basic copper carbonate formation reactions were obtained by Hess's law. • Processes of malachite and azurite formation from humus complexes are possible.

  4. Calculation of 0-0 excitation energies of organic molecules by CIS(D) quantum chemical methods

    International Nuclear Information System (INIS)

    Grimme, Stefan; Izgorodina, Ekaterina I.

    2004-01-01

    The accuracy and reliability of the CIS(D) quantum chemical method and a spin-component scaled variant (SCS-CIS(D)) are tested for calculating 0-0 excitation energies of organic molecules. The ground and excited state geometries and the vibrational zero-point corrections are taken from (TD)DFT-B3LYP calculations. In total 32 valence excited states of different character are studied: π → π* states of polycyclic aromatic compounds/polyenes and n → π* states of carbonyl, thiocarbonyl and aza(azo)-aromatic compounds. This set is augmented by two systems of special interest, i.e., indole and the TICT state of dimethylaminbenzonitrile (DMABN). Both methods predict excitation energies that are on average higher than experiment by about 0.2 eV. The errors are found to be quite systematic (with a standard deviation of about 0.15 eV) and especially SCS-CIS(D) provides a more balanced treatment of π → π* vs. n → π* states. For the test suite of states, both methods clearly outperform the (TD)DFT-B3LYP approach. Opposed to previous conclusions about the performance of CIS(D), these methods can be recommended as reliable and efficient tools for computational studies of excited state problems in organic chemistry. In order to obtain conclusive results, however, the use of optimized excited state geometries and comparison with observables (0-0 excitation energies) are necessary

  5. Quantum Chemical Calculations Using Accelerators: Migrating Matrix Operations to the NVIDIA Kepler GPU and the Intel Xeon Phi.

    Science.gov (United States)

    Leang, Sarom S; Rendell, Alistair P; Gordon, Mark S

    2014-03-11

    Increasingly, modern computer systems comprise a multicore general-purpose processor augmented with a number of special purpose devices or accelerators connected via an external interface such as a PCI bus. The NVIDIA Kepler Graphical Processing Unit (GPU) and the Intel Phi are two examples of such accelerators. Accelerators offer peak performances that can be well above those of the host processor. How to exploit this heterogeneous environment for legacy application codes is not, however, straightforward. This paper considers how matrix operations in typical quantum chemical calculations can be migrated to the GPU and Phi systems. Double precision general matrix multiply operations are endemic in electronic structure calculations, especially methods that include electron correlation, such as density functional theory, second order perturbation theory, and coupled cluster theory. The use of approaches that automatically determine whether to use the host or an accelerator, based on problem size, is explored, with computations that are occurring on the accelerator and/or the host. For data-transfers over PCI-e, the GPU provides the best overall performance for data sizes up to 4096 MB with consistent upload and download rates between 5-5.6 GB/s and 5.4-6.3 GB/s, respectively. The GPU outperforms the Phi for both square and nonsquare matrix multiplications.

  6. Molecular dynamic and quantum chemical calculations for phthalazine derivatives as corrosion inhibitors of mild steel in 1 M HCl

    Energy Technology Data Exchange (ETDEWEB)

    Musa, Ahmed Y., E-mail: AMUSA6@UWO.CA [Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7 (Canada); Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor (Malaysia); Jalgham, Ramzi T.T.; Mohamad, Abu Bakar [Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor (Malaysia)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The inhibition of three phthalazine derivatives was studied. Black-Right-Pointing-Pointer The inhibition efficiency increased in the following order: PTD < PT < PTO. Black-Right-Pointing-Pointer The adsorption energies were calculated using molecular dynamics simulations. Black-Right-Pointing-Pointer Quantum chemical parameters were calculated using the AM1, MNDO and PM3 methods. Black-Right-Pointing-Pointer The adsorption of phthalazine derivatives obeys the Langmuir adsorption isotherm. - Abstract: The abilities of phthalazine derivatives, including phthalazine (PT), phthalazone (PTO) and phthalhydrazide (PTD), to inhibit the corrosion of mild steel in 1 M HCl at 30 Degree-Sign C were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Theoretical calculations were performed to investigate the electronic structures of the PT derivatives. Our results showed that the inhibition efficiencies of these derivatives improved with increases in concentration. The data also showed that PTD < PT < PTO in terms of the inhibiting efficiency. Theoretical calculations also revealed that PTO is expected to be the best inhibitor among the studied phthalazine derivatives.

  7. Electrochemical and quantum chemical studies of some indole derivatives as corrosion inhibitors for C38 steel in molar hydrochloric acid

    International Nuclear Information System (INIS)

    Lebrini, M.; Robert, F.; Vezin, H.; Roos, C.

    2010-01-01

    A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 o C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The ΔG ads o values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).

  8. Quantum chemical study of the structure, spectroscopy and reactivity of NO+.(H2O) n=1-5 clusters.

    Science.gov (United States)

    Linton, Kirsty A; Wright, Timothy G; Besley, Nicholas A

    2018-03-13

    Quantum chemical methods including Møller-Plesset perturbation (MP2) theory and density functional theory (DFT) have been used to study the structure, spectroscopy and reactivity of NO + (H 2 O) n =1-5 clusters. MP2/6-311++G** calculations are shown to describe the structure and spectroscopy of the clusters well. DFT calculations with exchange-correlation functionals with a low fraction of Hartree-Fock exchange give a binding energy of NO + (H 2 O) that is too high and incorrectly predict the lowest energy structure of NO + (H 2 O) 2 , and this error may be associated with a delocalization of charge onto the water molecule directly binding to NO + Ab initio molecular dynamics (AIMD) simulations were performed to study the NO + (H 2 O) 5 [Formula: see text] H + (H 2 O) 4 + HONO reaction to investigate the formation of HONO from NO + (H 2 O) 5 Whether an intracluster reaction to form HONO is observed depends on the level of electronic structure theory used. Of note is that methods that accurately describe the relative energies of the product and reactant clusters did not show reactions on the timescales studied. This suggests that in the upper atmosphere the reaction may occur owing to the energy present in the NO + (H 2 O) 5 complex following its formation.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).

  9. Quantum Chemical Study on the Antioxidation Mechanism of Piceatannol and Isorhapontigenin toward Hydroxyl and Hydroperoxyl Radicals.

    Directory of Open Access Journals (Sweden)

    Yang Lu

    Full Text Available A systematic study of the antioxidation mechanisms behind hydroxyl (•OH and hydroperoxyl (•OOH radical scavenging activity of piceatannol (PIC and isorhapontigenin (ISO was carried out using density functional theory (DFT method. Two reaction mechanisms, abstraction (ABS and radical adduct formation (RAF, were discussed. A total of 24 reaction pathways of scavenging •OH and •OOH with PIC and ISO were investigated in the gas phase and solution. The thermodynamic and kinetic properties of all pathways were calculated. Based on these results, we evaluated the antioxidant activity of every active site of PIC and ISO and compared the abilities of PIC and ISO to scavenge radicals. According to our results, PIC and ISO may act as effective •OH and •OOH scavengers in organism. A4-hydroxyl group is a very important active site for PIC and ISO to scavenge radicals. The introducing of -OH or -OCH3 group to the ortho-position of A4-hydroxyl group would increase its antioxidant activity. Meanwhile, the conformational effect was researched, the results suggest that the presence and pattern of intramolecular hydrogen bond (IHB are considerable in determining the antioxidant activity of PIC and ISO.

  10. Information about AER WG A on improvement, extension and validation of parametrized few-group libraries for VVER 440 and VVER 1000

    International Nuclear Information System (INIS)

    Mikolas, P.

    2010-01-01

    Joint AER Working Group A on 'Improvement, extension and validation of parameterized few-group libraries for WWER-440 and WWER-1000' and AER Working Group B on 'Core design' nineteenth meeting was hosted by VUJE a. s. in Modra - Harmonia (Slovakia) during the period of 20. to 22. April 2010. There were present altogether 12 participants from 8 member organizations and 9 papers were presented (8 of them in written form). Objectives of the meeting of WG A are: Issues connected with spectral calculations and few-groups libraries preparation, their accuracy and validation. Presentations were devoted to some aspects of transport and diffusion calculations and to the benchmark dealing with WWER-1000 core periphery power tilt. Tamas Parko (co-authors Istvan Pos and Sandor Patai Szabo) described in his presentation 'Application of Discontinuity factors in C-PORCA 7 code', Radoslav Zajac (co-authors Petr Darilek and Vladimir Necas) spoke about 'Fast Reactor Nodalisation in HELIOS Code', Gabriel Farkas presented 'Calculation of Spatial Weighting Functions of Ex-Core Neutron Detectors for WWER-440 Using Monte Carlo Approach' and Daniel Sprinzl (co-authors Vaclav Krysl, Pavel Mikolas and Jiri Svarny) provided a definition of a benchmark in ' 'MIDICORE' WWER-1000 core periphery power tilt benchmark proposal'. (Author)

  11. Quantum-chemical study of halogenophyl interactions. 2. Modelling of halogenophyl reactions with participation chlorophosphonium

    International Nuclear Information System (INIS)

    Kobychev, V.B.; Virkovskaya, N.M.; Timokhin, B.V.; Golubin, A.I.

    1997-01-01

    Calculations of the model reactions (P(CH 3 ) n Cl 4-n + +Hlg - →P(CH 3 ) n Cl 3-n +Cl+Hg (Hlg=Cl, Br, I; n=0,1,2). It is shown that chlorine atom is a preferable object. The calculated heat of alogenophyl reactions is the highest one for PCl 4 + and decreases by substitution of chlorine atoms through methyl groups. The potential curves for all reactions contain the minima, corresponding to the complexes with the linear triad P-Cl-Hlg

  12. The inhibition effect of Azure A on mild steel in 1 M HCl. A complete study: Adsorption, temperature, duration and quantum chemical aspects

    International Nuclear Information System (INIS)

    Özkır, Demet; Kayakırılmaz, Kadriye; Bayol, Emel; Gürten, A. Ali; Kandemirli, Fatma

    2012-01-01

    Highlights: ► Azure A molecule is found to be a good inhibitor for mild steel in HCl solution. ► SEM results clearly indicate that a protective film formation occurred on the mild steel surface. ► The long term corrosion tests are cleared that the Azure A has effectively protected the mild steel in HCl solution. ► The quantum chemical measurements were cleared the reactive sites and charges of atoms in the molecule. - Abstract: In this study, inhibition effect of Azure A on mild steel in 1.0 M HCl were evaluated by using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and potentiodynamic polarization and scanning electron microscope (SEM) methods. These studies were carried out at different concentrations, temperatures and durations. The inhibitor molecules were chemisorbed on electrode surface according to the Langmuir adsorption isotherm. The quantum chemical calculations were employed to give further insight into the inhibition mechanism of Azure A.

  13. Towards a physical interpretation of substituent effect: Quantum chemical interpretation of Hammett substituent constants

    Science.gov (United States)

    Varaksin, Konstantin S.; Szatylowicz, Halina; Krygowski, Tadeusz M.

    2017-06-01

    Quantitative description of substituent effects is of a great importance especially in organic chemistry and QSAR-type treatments. The proposed approaches: substituent effect stabilization energy (SESE) and charge of the substituent active region (cSAR) provide substituent effect characteristics, physically independent of the Hammett's substituent constants, σ. To document abilities of these descriptors the B3LYP/6-311++G(d,p) method is employed to examine changes in properties of a reaction center Y (Y = COOH or COO- groups) and a transmitting moiety (benzene ring) due to substituent effects in a series of meta- and para-X-substituted benzoic acid and benzoate anion derivatives (X = NMe2, NH2, OH, OMe, CH3, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO). The transmitting moiety is described by aromaticity indices HOMA and NICS(1). Furthermore, an advantage of the cSAR characteristic is the ability to use it to describe both electron donating/accepting properties of a substituent as well as a reaction center. It allows demonstration of the reverse substituent effects of COOH and COO- groups on substituent X.

  14. Quantum Chemical and Experimental Studies on the Mechanism of Alkylation of β-Dicarbonyl Compounds. The Synthesis of Five and Six Membered Heterocyclic Spiro Derivatives

    Directory of Open Access Journals (Sweden)

    Ali Hüseyinli

    2004-11-01

    Full Text Available The alkylation of β-dicarbonyl compounds in a K2CO3/DMSO system wasfound to afford O- and C-alkylated derivatives, depending on the type of the β-dicarbonylcompound involved. The alkyl derivatives obtained were used in the synthesis of some newspiro barbituric acid derivatives. Quantum chemical calculations were carried out toelucidate the reaction mechanisms for some typical synthesis.

  15. Vibrational, NMR and quantum chemical investigations of acetoacetanilde, 2-chloroacetoacetanilide and 2-methylacetoacetanilide.

    Science.gov (United States)

    Arjunan, V; Kalaivani, M; Senthilkumari, S; Mohan, S

    2013-11-01

    The vibrational assignment and analysis of the fundamental modes of the compounds acetoacetanilide (AAA), 2-chloroacetoacetanilide (2CAAA) and 2-methylacetoacetanilide (2MAAA) have been performed. Density functional theory studies have been carried out with B3LYP method utilising 6-311++G(**) and cc-pVTZ basis sets to determine structural, thermodynamic and vibrational characteristics of the compounds and also to understand the influence of chloro and methyl groups on the characteristic frequencies of amide (CONH) group. Intramolecular hydrogen bond exists in acetoacetanilide and o-substituted acetoacetanilide molecules and the N⋯O distance is found to be around 2.7Å. The (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecules were determined and the same have been calculated using the gauge independent atomic orbital (GIAO) method. The energies of the frontier molecular orbitals have been determined. In AAA, 2CAAA and 2MAAA molecules, the nN→πCO(∗) interaction between the nitrogen lone pair and the amide CO antibonding orbital gives strong stabilization of 64.75, 62.84 and 64.18kJmol(-1), respectively. The blue shift in amide-II band of 2MAAA is observed by 45-50cm(-1) than that of AAA. The steric effect of ortho methyl group significantly operating on the NH bond properties. The amide-III, the CN stretching mode of methyl and chloro substituted acetoacetanilide compounds are not affected by the substitution while the amide-V band, the NH out of plane bending mode of 2-chloroacetoacetanilide compound is shifted to a higher frequency than that of AAA. The substituent chlorine plays significantly and the blue shift in o-substituted compounds than the parent in the amide-V vibration is observed. The amide-VI, CO out of plane bending modes of 2MAAA and 2CAAA are significantly raised than that of AAA. A blue shift of amide-VI, CO out of plane bending modes of 2MAAA and 2CAAA than AAA is observed. Copyright © 2013 Elsevier B.V. All rights

  16. Synthesis, vibrational, NMR, quantum chemical and structure-activity relation studies of 2-hydroxy-4-methoxyacetophenone.

    Science.gov (United States)

    Arjunan, V; Devi, L; Subbalakshmi, R; Rani, T; Mohan, S

    2014-09-15

    The stable geometry of 2-hydroxy-4-methoxyacetophenone is optimised by DFT/B3LYP method with 6-311++G(∗∗) and cc-pVTZ basis sets. The structural parameters, thermodynamic properties and vibrational frequencies of the optimised geometry have been determined. The effects of substituents (hydroxyl, methoxy and acetyl groups) on the benzene ring vibrational frequencies are analysed. The vibrational frequencies of the fundamental modes of 2-hydroxy-4-methoxyacetophenone have been precisely assigned and analysed and the theoretical results are compared with the experimental vibrations. 1H and 13C NMR isotropic chemical shifts are calculated and assignments made are compared with the experimental values. The energies of important MO's, the total electron density and electrostatic potential of the compound are determined. Various reactivity and selectivity descriptors such as chemical hardness, chemical potential, softness, electrophilicity, nucleophilicity and the appropriate local quantities are calculated. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Quantum-chemical calculation of energies and spectral characteristics of conformers in derivatives of phenylphosphine

    International Nuclear Information System (INIS)

    Chuvashev, D.D.; Ratovskii, G.V.; Zakzhevskii, V.G.

    1987-01-01

    The phenylphosphines PhPX 2 calculated by the MNDO method are characterized by two potential minima corresponding to the bisector and gonal conformations. For X = Cl, F, and C=N the bisector conformer predominates considerably, but for X = H and CH 3 the populations of the conformers are approximately the same. The characteristics of the electron transitions of the conformers found, determined by the CNDO/S method, differ substantially, which makes it possible to analyze the conformational compositions of arylphosphines by means of UV spectroscopy. In excited ππ* states the gonal conformation is characterized by a substantial donor effect of the PX 2 group, whereas the bisector conformation gives a certain acceptor effect

  18. Evidence for excited-state intramolecular proton transfer in 4-chlorosalicylic acid from combined experimental and computational studies: Quantum chemical treatment of the intramolecular hydrogen bonding interaction

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Bijan Kumar [Department of Chemistry, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009 (India); Guchhait, Nikhil, E-mail: nikhil.guchhait@rediffmail.com [Department of Chemistry, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009 (India)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Experimental and computational studies on the photophysics of 4-chlorosalicylic acid. Black-Right-Pointing-Pointer Spectroscopically established ESIPT reaction substantiated by theoretical calculation. Black-Right-Pointing-Pointer Quantum chemical treatment of IMHB unveils strength, nature and directional nature. Black-Right-Pointing-Pointer Superiority of quantum chemical treatment of H-bond over geometric criteria. Black-Right-Pointing-Pointer Role of H-bond as a modulator of aromaticity. -- Abstract: The photophysical study of a pharmaceutically important chlorine substituted derivative of salicylic acid viz., 4-chlorosalicylic acid (4ClSA) has been carried out by steady-state absorption, emission and time-resolved emission spectroscopy. A large Stokes shifted emission band with negligible solvent polarity dependence marks the spectroscopic signature of excited-state intramolecular proton transfer (ESIPT) reaction in 4ClSA. Theoretical calculation by ab initio and Density Functional Theory methods yields results consistent with experimental findings. Theoretical potential energy surfaces predict the occurrence of proton transfer in S{sub 1}-state. Geometrical and energetic criteria, Atoms-In-Molecule topological parameters, Natural Bond Orbital population analysis have been exploited to evaluate the intramolecular hydrogen bond (IMHB) interaction and to explore its directional nature. The inter-correlation between aromaticity and resonance assisted H-bond is also discussed in this context. Our results unveil that the quantum chemical treatment is a more accurate tool to assess hydrogen bonding interaction in comparison to geometrical criteria.

  19. Quantum chemical modeling of perovskite: An investigation of piezoelectricity in ferrite of yttrium.

    Science.gov (United States)

    de Lira, Fábio Augusto M; Farias, Márcio de Souza; de Figueiredo, Antonio Florêncio; Gil, Fábio dos Santos; dos Santos, Marcos Antonio B; Malheiros, Bruno Veiga; Ferreira, João Elias V; Pinheiro, José Ciríaco; Treu-Filho, Oswaldo; Kondo, Rogério Toshiaki

    2011-07-01

    In a previous article, we used Hartree-Fock (HF) theory to study the piezoelectricity in BaTiO₃. In this paper, we applied the Douglas-Kroll-Hess second order scalar relativistic method to investigate the possible piezoelectric properties in the perovskite YFeO₃ structure, which has not yet been studied experimentally. The 30s20p13d and 31s21p17d Gaussian basis sets for the Fe (⁵D) and Y (²D) atoms, respectively, were built with the Generator Coordinate HF method. After contraction to [13s7p5d] and [13s8p7d], in combination with the 20s14p/6s4p basis set for the O (³P) atom from literature, they had their quality evaluated using calculations of the total and the orbital energies for the ²FeO⁺¹ and ¹YO⁺¹ fragments. The dipole moment, the total energy, and the total atomic charges in YFeO₃ in C(s) space group were calculated. The results and the analysis lead us to believe that the perovskite YFeO₃ does not present piezoelectric properties.

  20. Quantum chemical study on gas phase pyrolysis of p-isopropenylphenol.

    Science.gov (United States)

    Mohan Verma, Anand; Kawale, Harshal D; Agrawal, Kushagra; Kishore, Nanda

    2018-05-01

    In the pyrolysis of Sphagnum moss species, p-isopropenylphenol (p-IPP) is a major product which has been considered in this density functional theory based computational study for its conversion to various products such as benzene, phenol, 4-propenylphenol, indan-5-ol, 4-propylcyclohexanone, 4-cyclopropylphenol, etc. In order to achieve these products, eight different reaction schemes are performed using B3LYP/6-311 + g (d,p) level of theory. Further, thermodynamic properties such as reaction free energies and reaction enthalpies associated with these eight reaction schemes are developed in the temperature range of 298-898 K. The reaction schemes that include partial hydrogenation of the aromatic carbon followed by elimination of functional groups are found to demand low activation energy. The production of benzene from p-IPP with isopropenylbenzene as an intermediate product requiring only 19.83 kcal/mol of activation energy is the rate limiting reaction step. Indan-5-ol produced from p-IPP is validated with the literature results and found excellent agreement between two results. Furthermore, the temperature is found to have phenomenal effect in each reaction scheme. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Synthesis, characterization, crystal structure and quantum chemical investigations of three novel coumarin-benzenesulfonohydrazide derivatives

    Science.gov (United States)

    Chethan Prathap, K. N.; Lokanath, N. K.

    2018-04-01

    Coumarin derivatives are an important class of heterocyclic compounds due to their physical and biological properties. Coumarin derivatives have been identified with many significant electro-optical properties and biological activities. Three novel coumarin derivatives containing benzene sulfonohydrazide group were synthesized by condensation reaction. The synthesized compounds were characterized by various spectroscopic techniques (Mass, 1H/13C NMR and FTIR). Thermal and optical properties were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and UV-Vis spectroscopic studies. Finally their structures were confirmed by single crystal X-ray diffraction (XRD) studies. The three compounds exhibit diverse intermolecular interactions, as observed by the crystal packing and Hirshfeld surface analysis. Further, their structures were optimized by density functional theory (DFT) calculations using B3LYP hybrid functionals with 6-311G+(d,p) level basis set. The Mulliken charge, molecular electrostatic potential (MEP), frontier molecular orbitals (HOMO-LUMO) were investigated. The experimentally determined parameters were compared with those calculated theoretically and they complement each other with a very good correlation. The transitions among the molecular orbitals were investigated using time-dependent density functional theory (TD-DFT) and the electronic absorption spectra obtained showed very good agreement with the experimentally measured UV-Vis spectra. Furthermore, non-linear optical (NLO) properties were investigated by calculating polarizabilities and hyperpolarizabilities. All three compounds exhibit significantly high hyperpolarizabilities compared to the reference material urea, which makes them potential candidates for NLO applications.

  2. Benefits of extensive recruitment effort persist during follow-ups and are consistent across age group and survey method. The TRAILS study

    Directory of Open Access Journals (Sweden)

    Nederhof Esther

    2012-07-01

    Full Text Available Abstract Background Extensive recruitment effort at baseline increases representativeness of study populations by decreasing non-response and associated bias. First, it is not known to what extent increased attrition occurs during subsequent measurement waves among subjects who were hard-to-recruit at baseline and what characteristics the hard-to-recruit dropouts have compared to the hard-to-recruit retainers. Second, it is unknown whether characteristics of hard-to-recruit responders in a prospective population based cohort study are similar across age group and survey method. Methods First, we compared first wave (T1 easy-to-recruit with hard-to-recruit responders of the TRacking Adolescents’ Individual Lives Survey (TRAILS, a prospective population based cohort study of Dutch (preadolescents (at first wave: n = 2230, mean age = 11.09 (SD 0.56, 50.8% girls, with regard to response rates at subsequent measurement waves. Second, easy-to-recruit and hard-to-recruit participants at the fourth TRAILS measurement wave (n = 1881, mean age = 19.1 (SD 0.60, 52.3% girls were compared with fourth wave non-responders and earlier stage drop-outs on family composition, socioeconomic position (SEP, intelligence (IQ, education, sociometric status, substance use, and psychopathology. Results First, over 60% of the hard-to-recruit responders at the first wave were retained in the sample eight years later at the fourth measurement wave. Hard-to-recruit dropouts did not differ from hard-to-recruit retainers. Second, extensive recruitment efforts for the web based survey convinced a population of nineteen year olds with similar characteristics as the hard-to-recruit eleven year olds that were persuaded to participate in a school-based survey. Some characteristics associated with being hard-to-recruit (as compared to being easy-to-recruit were more pronounced among non-responders, resembling the baseline situation (De Winter et al.2005

  3. Benefits of extensive recruitment effort persist during follow-ups and are consistent across age group and survey method. The TRAILS study.

    Science.gov (United States)

    Nederhof, Esther; Jörg, Frederike; Raven, Dennis; Veenstra, René; Verhulst, Frank C; Ormel, Johan; Oldehinkel, Albertine J

    2012-07-02

    Extensive recruitment effort at baseline increases representativeness of study populations by decreasing non-response and associated bias. First, it is not known to what extent increased attrition occurs during subsequent measurement waves among subjects who were hard-to-recruit at baseline and what characteristics the hard-to-recruit dropouts have compared to the hard-to-recruit retainers. Second, it is unknown whether characteristics of hard-to-recruit responders in a prospective population based cohort study are similar across age group and survey method. First, we compared first wave (T1) easy-to-recruit with hard-to-recruit responders of the TRacking Adolescents' Individual Lives Survey (TRAILS), a prospective population based cohort study of Dutch (pre)adolescents (at first wave: n = 2230, mean age = 11.09 (SD 0.56), 50.8% girls), with regard to response rates at subsequent measurement waves. Second, easy-to-recruit and hard-to-recruit participants at the fourth TRAILS measurement wave (n = 1881, mean age = 19.1 (SD 0.60), 52.3% girls) were compared with fourth wave non-responders and earlier stage drop-outs on family composition, socioeconomic position (SEP), intelligence (IQ), education, sociometric status, substance use, and psychopathology. First, over 60% of the hard-to-recruit responders at the first wave were retained in the sample eight years later at the fourth measurement wave. Hard-to-recruit dropouts did not differ from hard-to-recruit retainers. Second, extensive recruitment efforts for the web based survey convinced a population of nineteen year olds with similar characteristics as the hard-to-recruit eleven year olds that were persuaded to participate in a school-based survey. Some characteristics associated with being hard-to-recruit (as compared to being easy-to-recruit) were more pronounced among non-responders, resembling the baseline situation (De Winter et al.2005). First, extensive recruitment effort at the first

  4. Benefits of extensive recruitment effort persist during follow-ups and are consistent across age group and survey method. The TRAILS study

    Science.gov (United States)

    2012-01-01

    Background Extensive recruitment effort at baseline increases representativeness of study populations by decreasing non-response and associated bias. First, it is not known to what extent increased attrition occurs during subsequent measurement waves among subjects who were hard-to-recruit at baseline and what characteristics the hard-to-recruit dropouts have compared to the hard-to-recruit retainers. Second, it is unknown whether characteristics of hard-to-recruit responders in a prospective population based cohort study are similar across age group and survey method. Methods First, we compared first wave (T1) easy-to-recruit with hard-to-recruit responders of the TRacking Adolescents’ Individual Lives Survey (TRAILS), a prospective population based cohort study of Dutch (pre)adolescents (at first wave: n = 2230, mean age = 11.09 (SD 0.56), 50.8% girls), with regard to response rates at subsequent measurement waves. Second, easy-to-recruit and hard-to-recruit participants at the fourth TRAILS measurement wave (n = 1881, mean age = 19.1 (SD 0.60), 52.3% girls) were compared with fourth wave non-responders and earlier stage drop-outs on family composition, socioeconomic position (SEP), intelligence (IQ), education, sociometric status, substance use, and psychopathology. Results First, over 60% of the hard-to-recruit responders at the first wave were retained in the sample eight years later at the fourth measurement wave. Hard-to-recruit dropouts did not differ from hard-to-recruit retainers. Second, extensive recruitment efforts for the web based survey convinced a population of nineteen year olds with similar characteristics as the hard-to-recruit eleven year olds that were persuaded to participate in a school-based survey. Some characteristics associated with being hard-to-recruit (as compared to being easy-to-recruit) were more pronounced among non-responders, resembling the baseline situation (De Winter et al.2005). Conclusions First, extensive

  5. Prediction of pKa Values for Druglike Molecules Using Semiempirical Quantum Chemical Methods.

    Science.gov (United States)

    Jensen, Jan H; Swain, Christopher J; Olsen, Lars

    2017-01-26

    Rapid yet accurate pK a prediction for druglike molecules is a key challenge in computational chemistry. This study uses PM6-DH+/COSMO, PM6/COSMO, PM7/COSMO, PM3/COSMO, AM1/COSMO, PM3/SMD, AM1/SMD, and DFTB3/SMD to predict the pK a values of 53 amine groups in 48 druglike compounds. The approach uses an isodesmic reaction where the pK a value is computed relative to a chemically related reference compound for which the pK a value has been measured experimentally or estimated using a standard empirical approach. The AM1- and PM3-based methods perform best with RMSE values of 1.4-1.6 pH units that have uncertainties of ±0.2-0.3 pH units, which make them statistically equivalent. However, for all but PM3/SMD and AM1/SMD the RMSEs are dominated by a single outlier, cefadroxil, caused by proton transfer in the zwitterionic protonation state. If this outlier is removed, the RMSE values for PM3/COSMO and AM1/COSMO drop to 1.0 ± 0.2 and 1.1 ± 0.3, whereas PM3/SMD and AM1/SMD remain at 1.5 ± 0.3 and 1.6 ± 0.3/0.4 pH units, making the COSMO-based predictions statistically better than the SMD-based predictions. For pK a calculations where a zwitterionic state is not involved or proton transfer in a zwitterionic state is not observed, PM3/COSMO or AM1/COSMO is the best pK a prediction method; otherwise PM3/SMD or AM1/SMD should be used. Thus, fast and relatively accurate pK a prediction for 100-1000s of druglike amines is feasible with the current setup and relatively modest computational resources.

  6. Quantum-chemical studies on the favored and rare tautomers of neutral and redox adenine.

    Science.gov (United States)

    Raczyńska, Ewa D; Makowski, Mariusz; Zientara-Rytter, Katarzyna; Kolczyńska, Katarzyna; Stępniewski, Tomasz M; Hallmann, Małgorzata

    2013-02-21

    All possible twenty-three prototropic tautomers of neutral and redox adenine (nine amine and fourteen imine forms, including geometric isomerism of the exo ═NH group) were examined in vacuo {DFT(B3LYP)/6-311+G(d,p)}. The NH → NH conversions as well as those usually omitted, NH → CH and CH → CH, were considered. An interesting change of the tautomeric preference occurs when proceeding from neutral to reduced adenine. One-electron reduction favors the nonaromatic amine C8H-N10H tautomer. This tautomeric preference is similar to that (C2H) for reduced imidazole. Water molecules (PCM model) seem to not change this trend. They influence solely the relative energies. The DFT vertical detachment energy in the gas phase is positive for each tautomer, e.g., 0.03 eV for N9H-N10H and 1.84 eV for C8H-N10H. The DFT adiabatic electron affinity for the favored process, neutral N9H-N10H → reduced C8H-N10H (ground states), is equal to 0.18 eV at 0 K (ZPE included). One-electron oxidation does not change the tautomeric preference in the gas phase. The aromatic amine N9H-N10H tautomer is favored for the oxidized molecule similarly as for the neutral one. The DFT adiabatic ionization potential for the favored process, neutral N9H-N10H → oxidized N9H-N10H (ground states), is equal to 8.12 eV at 0 K (ZPE included). Water molecules (PCM model) seem to influence solely the composition of the tautomeric mixture and the relative energies. They change the energies of the oxidation and reduction processes by ca. 2 eV.

  7. Quantum chemical investigation of attractive non-covalent interactions between halomethanes and rare gases.

    Science.gov (United States)

    McAllister, Linda J; Bruce, Duncan W; Karadakov, Peter B

    2012-11-01

    The interaction between rare gas atoms and trifluoromethylhalides and iodomethane is investigated using ab initio and density functional theory (DFT) methods: MP2, CCSD, B3LYP, M06, M06-L, M06-2X, M06-HF, X3LYP, PBE, B97-D, B3LYP-D3, and M06-L-D3, in combination with the aug-cc-pVTZ and aug-cc-pVTZ-PP basis sets. A weakly attractive interaction is observed for all complexes, whose strength increases as the rare gas and halogen bond donor become more polarizable, and as the group bound to the halogen bond donor becomes more electron-withdrawing. The separation between iodine and krypton in the complex CF(3)I···Kr, calculated at the MP2 and B3LYP-D3 levels of theory, agrees very well with recent experimental results (Stephens, S. L.; Walker, N. R.; Legon, A. C. J. Chem. Phys. 2011, 135, 224309). Analysis of the ability of theoretical methods to account for the dispersion interaction present in these complexes leads to the conclusion that MP2 and B3LYP-D3, which produce very similar results, are the better performing methods, followed by B97-D and the M06 suite of functionals; the popular B3LYP as well as X3LYP perform poorly and significantly underestimate the interaction strength. The orbitals responsible for the interaction are identified through Edmiston-Ruedenberg localization; it is shown that, by combining the key orbitals, it is possible to observe a molecular orbital picture of a σ-hole interaction.

  8. Influence of electron correlation and degeneracy on the Fukui matrix and extension of frontier molecular orbital theory to correlated quantum chemical methods.

    Science.gov (United States)

    Bultinck, Patrick; Van Neck, Dimitri; Acke, Guillaume; Ayers, Paul W

    2012-02-21

    The Fukui function is considered as the diagonal element of the Fukui matrix in position space, where the Fukui matrix is the derivative of the one particle density matrix (1DM) with respect to the number of electrons. Diagonalization of the Fukui matrix, expressed in an orthogonal orbital basis, explains why regions in space with negative Fukui functions exist. Using a test set of molecules, electron correlation is found to have a remarkable effect on the eigenvalues of the Fukui matrix. The Fukui matrices at the independent electron model level are mathematically proven to always have an eigenvalue equal to exactly unity while the rest of the eigenvalues possibly differ from zero but sum to zero. The loss of idempotency of the 1DM at correlated levels of theory causes the loss of these properties. The influence of electron correlation is examined in detail and the frontier molecular orbital concept is extended to correlated levels of theory by defining it as the eigenvector of the Fukui matrix with the largest eigenvalue. The effect of degeneracy on the Fukui matrix is examined in detail, revealing that this is another way by which the unity eigenvalue and perfect pairing of eigenvalues can disappear.

  9. Spectral analysis and quantum chemical studies of chair and twist-boat conformers of cycloheximide in gas and solution phases

    Science.gov (United States)

    Tokatli, A.; Ucun, F.; Sütçü, K.; Osmanoğlu, Y. E.; Osmanoğlu, Ş.

    2018-02-01

    In this study the conformational behavior of cycloheximide in the gas and solution (CHCl3) phases has theoretically been investigated by spectroscopic and quantum chemical properties using density functional theory (wB97X-D) method with 6-31++G(d,p) basis set, for the first time. The calculated IR results reveal that in the ground state the molecule exits as a mixture of the chair and twist-boat conformers in the gas phase, while the calculated NMR results reveal that it only exits as the chair conformer in the solution phase. In order to obtain the contributions coming from intramolecular interactions to the stability of the conformers in the gas and solution phases, the quantum theory of atoms in molecules (QTAIM), noncovalent interactions (NCI) method, and natural bond orbital analysis (NBO) have been employed. The QTAIM and NCI methods indicated that by intramolecular interactions with bond critical point (BCP) the twist-boat conformer is more stabilized than the chair conformer, while by steric interactions it is more destabilized. Considering that these interactions balance each other, the stabilities of the conformers are understood to be dictated by the van der Waals interactions. The NBO analyses show that the hyperconjugative and steric effects play an important role in the stabilization in the gas and solution phases. Furthermore, to get a better understanding of the chemical behavior of this important antibiotic drug we have evaluated and, commented the global and local reactivity descriptors of the both conformers. Finally, the EPR analysis of γ-irradiated cycloheximide has been done. The comparison of the experimental and calculated data have showed the inducement of a radical structure of (CH2)2ĊCH2 in the molecule. The experimental EPR spectrum has also confirmed that the molecule simultaneously exists in the chair and twist-boat conformers in the solid phase.

  10. A quantum chemical study of the N2H+ + e- → N2 + H reaction I: The linear dissociation path

    International Nuclear Information System (INIS)

    Talbi, D.

    2007-01-01

    A theoretical investigation of the dissociative recombination (DR) of linear N 2 H + (X 1 Σ g + ) to give N 2 + H has been undertaken because it is of interest for astrochemistry and also because it has been recently studied experimentally. Using state of the art quantum chemical methods, it is shown that the lowest 2 Σ repulsive state of N 2 H leading to the N 2 and H fragments in their ground electronic states does not cross the curve of the ion nor the one of the lowest N 2 H Rydberg state. This lowest 2 Σ repulsive state is very low in energy. Its curve passes below the 1 Σ N 2 H + state and below the lowest bound 2 Σ N 2 H states. However, it is also shown that there exist higher repulsive 2 Σ and 2 Δ states of N 2 H (the second and third repulsive states) crossing the ion curve. These states will lead to the formation of N 2 in its 3 Σ u + and 3 Δ u states. This study, the first of its type, shows that the DR of linear N 2 H + should involve the direct mechanism and that it should lead to N 2 in its first excited states. However this process may not be efficient for N 2 H + in its ground vibrational state (v = 0), a state in which it exists in the cold environment of the interstellar medium. For the DR to be efficient for N 2 H + in its ground v = 0 vibrational state, bent geometries of the ion might have to be considered

  11. Revealing the importance of linkers in K-series oxime reactivators for tabun-inhibited AChE using quantum chemical, docking and SMD studies.

    Science.gov (United States)

    Ghosh, Shibaji; Chandar, Nellore Bhanu; Jana, Kalyanashis; Ganguly, Bishwajit

    2017-08-01

    Inhibition of acetylcholinesterase (AChE) with organophosphorus compounds has a detrimental effect on human life. Oxime K203 seems to be one of the promising reactivators for tabun-inhibited AChE than (K027, K127, and K628). These reactivators differ only in the linker units between the two pyridinium rings. The conformational analyses performed with quantum chemical RHF/6-31G* level for K027, K127, K203 and K628 showed that the minimum energy conformers have different orientations of the active and peripheral pyridinium rings for these reactivator molecules. K203 with (-CH 2 -CH=CH-CH 2 -) linker unit possesses more open conformation compared to the other reactivators. Such orientation of K203 experiences favorable interaction with the surrounding residues of catalytic anionic site (CAS) and peripheral anionic site (PAS) of tabun-inhibited AChE. From the steered molecular dynamics simulations, it has been observed that the oxygen atom of the oxime group of K203 reactivator approaches nearest to the P-atom of the SUN203 (3.75 Å) at lower time scales (less than ~1000 ps) as compared to the other reactivators. K203 experiences less number of hydrophobic interaction with the PAS residues which is suggested to be an important factor for the efficient reactivation process. In addition, K203 crates large number of H-bonding with CAS residues SUN203, Phe295, Tyr337, Phe338 and His447. K203 barely changes its conformation during the SMD simulation process and hence the energy penalty to adopt any other conformation is minimal in this case as compared to the other reactivators. The molecular mechanics and Poisson-Boltzmann surface area binding energies obtained for the interaction of K203 inside the gorge of tabun inhibited AChE is substantially higher (-290.2 kcal/mol) than the corresponding K628 reactivator (-260.4 kcal/mol), which also possess unsaturated aromatic linker unit.

  12. Revealing the importance of linkers in K-series oxime reactivators for tabun-inhibited AChE using quantum chemical, docking and SMD studies

    Science.gov (United States)

    Ghosh, Shibaji; Chandar, Nellore Bhanu; Jana, Kalyanashis; Ganguly, Bishwajit

    2017-08-01

    Inhibition of acetylcholinesterase (AChE) with organophosphorus compounds has a detrimental effect on human life. Oxime K203 seems to be one of the promising reactivators for tabun-inhibited AChE than (K027, K127, and K628). These reactivators differ only in the linker units between the two pyridinium rings. The conformational analyses performed with quantum chemical RHF/6-31G* level for K027, K127, K203 and K628 showed that the minimum energy conformers have different orientations of the active and peripheral pyridinium rings for these reactivator molecules. K203 with (-CH2-CH=CH-CH2-) linker unit possesses more open conformation compared to the other reactivators. Such orientation of K203 experiences favorable interaction with the surrounding residues of catalytic anionic site (CAS) and peripheral anionic site (PAS) of tabun-inhibited AChE. From the steered molecular dynamics simulations, it has been observed that the oxygen atom of the oxime group of K203 reactivator approaches nearest to the P-atom of the SUN203 (3.75 Å) at lower time scales (less than 1000 ps) as compared to the other reactivators. K203 experiences less number of hydrophobic interaction with the PAS residues which is suggested to be an important factor for the efficient reactivation process. In addition, K203 crates large number of H-bonding with CAS residues SUN203, Phe295, Tyr337, Phe338 and His447. K203 barely changes its conformation during the SMD simulation process and hence the energy penalty to adopt any other conformation is minimal in this case as compared to the other reactivators. The molecular mechanics and Poisson-Boltzmann surface area binding energies obtained for the interaction of K203 inside the gorge of tabun inhibited AChE is substantially higher (-290.2 kcal/mol) than the corresponding K628 reactivator (-260.4 kcal/mol), which also possess unsaturated aromatic linker unit.

  13. The southwestern extension of the Jiao-Liao-Ji belt in the North China Craton: Geochronological and geochemical evidence from the Wuhe Group in the Bengbu area

    Science.gov (United States)

    Liu, Chaohui; Zhao, Guochun; Liu, Fulai; Cai, Jia

    2018-04-01

    The Wuhe complex is located at the southeastern margin of the North China Craton. The complex consists of metamorphosed Paleoproterozoic potassic granitoids and supracrustal rocks, of which the latter include the Fengyang and Wuhe groups. Meta-mafic rocks from the lower Wuhe Group have igneous zircon U-Pb ages of 2126 ± 37 Ma with εHf(t) values of -6.22 to +8.38, and xenocrystic zircons of 2.39-2.36 Ga, 2.55-2.54 Ga and 2.77-2.69 Ga. Geochemically, the meta-mafic rocks can be classified into two groups. Group 1 island arc tholeiites display flat to slightly right declined REE patterns and moderately negative Nb, Ta, Zr, and Ti anomalies. Group 2 mature arc calcalkaline basalts display strongly fractionated chondrite-normalized REE patterns and evidently negative Nb, Ta and Ti anomalies. These meta-mafic rocks formed by partial melting of sub-arc depleted mantle wedge which had been modified by slab-derived melts at an active continental margin. Depositional age of the group can be constrained in the period of 2.16-2.10 Ga based on ages of the youngest detrital zircons and latter intrusions. U-Pb ages of detrital zircons yield major age peaks of 2.69 Ga and 2.52 Ga, with minor peaks at 2.88 Ga, 2.78 Ga, 2.35 Ga and 2.17 Ga, most of which are derived from the late Mesoarchean to early Paleoproterozoic granitoids in the Wuhe complex and the Jiaodong Terrane. Metamorphic zircons in the marbles coexisting with garnet amphibolites or granulites occur as either single grains or overgrowth (or recrystallization) rims surrounding magmatic zircon cores and yield ages of 1882 ± 19 Ma to 1844 ± 15 Ma. The comparable ca. 2.1 Ga potassic granites with A-type granite affinity, the ca. 2.1 Ga meta-mafic rocks with arc-like geochemical features, the 2.1-1.9 Ga meta-sedimentary units and the 1.9-1.8 Ga subduction- and collision-related granulite-facies metamorphism suggest that the Wuhe complex and the Jiao-Liao-Ji Belt share the same late Paleoproterozoic tectonic evolution

  14. High and low oxidation states and special bonding situations. An investigation of f-elements, xenon and fluorine by matrix-isolation spectroscopy and quantum-chemical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Vent-Schmidt, Thomas

    2015-11-30

    calculated Ln-F bond dissociation energy in these species is high enough that these compounds will be stable under cryogenic conditions. SmF{sub 4} and HoF{sub 4} are not observed although HoF{sub 4} might be stable according to the calculations. In all of the above mentioned experiments using F{sub 2} as reagent a so far unknown band at 850.7 cm{sup -1} has been observed in neon matrixes. Several attempts to experimentally identify the carrier of this bands are reported herein. In conjunction with quantumchemical methods the band can be attributed to a V-shaped [F{sub 5}]{sup -} anion which solves an outstanding question in our group we dealed with for already five years. In addition, the Cs{sup +}[F{sub 3}]{sup -} ion pair complex is further characterized in neon matrixes and the electronic structure is evaluated using state-of-the-art coupled cluster techniques. Using the experience with neat fluorine matrixes the chemical reactivity of the unstable Xe(VIII) oxide, XeO{sub 4}, was tested in fluorine doped neon, argon and krypton matrixes as well as in neat fluorine. However, the reactivity tend out to be low and no oxyfluoride or fluoride formation is observed. On photolysis with a 365 nm UVLED the new xenon (VIII) oxide, (η{sup 2}-O{sub 2})XeO{sub 3}, can be obtained and our results are confirmed by experiments using isotopic substituted 18O-enriched material as well as by quantum-chemical structure calculations. The photochemical process has been investigated theoretically and gives further insights in the photochemistry of XeO4 and the reaction channel to (η{sup 2}-O{sub 2})XeO{sub 3}. Further experiments to investigate the reaction of XeO{sub 4} with XeF{sub 6} would be interesting but are beyond the scope of this thesis.

  15. ["Vocational perspective"--short-term efficacy of a group treatment for patients with extensive work-related problems during medical rehabilitation].

    Science.gov (United States)

    Bönisch, A; Dorn, M; Ehlebracht-König, I

    2012-01-01

    To analyze the short-term efficacy of the Vocational Perspective programme for patients identified as having extensive work-related problems during rheumatology or orthopaedic inpatient rehabilitation. The primary objectives of the programme on patient level are to convey information about the legal provisions regarding earning incapacity and occupational reintegration, to suggest strategies for dealing with one's own occupational situation, and to strengthen the motivation to stay employed. The programme is explicitly designed for patients who wish to retire or have applied for a pension. On the systemic level, the main goals are to facilitate doctor-patient communication and to increase rehabilitation teams' awareness of occupational problems. In a controlled quasi-experimental design, 359 subjects were consecutively assigned to either the control group (CG, n=177) or the intervention group (IG, n=182). The control group received standard care only, whereas the intervention group additionally participated in the 5-part Vocational Perspective programme. Evaluation criteria were assessed by questionnaire at the beginning (t1) and at end of rehabilitation (t2). Survey participation was 92.2% at t2. The socio-medically relevant knowledge status was objectively documented using a specially designed knowledge questionnaire. Aspects of treatment satisfaction were evaluated using individual items, and the subjective prognosis of gainful employment was assessed using the Subjective Prognosis of Gainful Employment (SPE) scale. Facilitation of communication between doctor and patient was operationalized at patient level in terms of patient satisfaction with medical care, and increased awareness of the rehabilitation team was operationalized in terms of the rate of recommendations to apply for vocational reintegration (LTA) services at discharge. Emotional and functional parameters were exploratively analyzed (anxiety and depression using the IRES 3.1 scales, and

  16. Phase II trial of paclitaxel and cisplatin in patients with extensive stage small cell lung cancer: Cancer and Leukemia Group B Trial 9430.

    Science.gov (United States)

    Stinchcombe, Thomas E; Mauer, Ann M; Hodgson, Lydia D; Herndon, James E; Lynch, Thomas J; Green, Mark R; Vokes, Everett E

    2008-11-01

    Cancer and Leukemia Group B trial 9430 was a randomized phase II trial which investigated the safety and activity of four novel doublets in untreated extensive stage small cell lung cancer. The results of the paclitaxel and cisplatin arm have not been reported. Patients received paclitaxel 230 mg/m followed by cisplatin 75 mg/m on day 1 every 21 days. All patients received granulocyte colony stimulating factor 5 microg/kg/d beginning on day 3 of each cycle. The patient characteristics of the 34 patients assigned to this treatment arm were: median age 61.5 years (range 41-82), male (76%), performance status 0 (41%), 1 (32%), and 2 (26%). An objective response was observed in 23 patients (68%; 95% confidence interval (CI): 49-83%); 2 complete responses (6%) and 21 partial responses (62%). Median progression-free survival time was 5.6 months (95% CI: 4.8-7.1 month), and median overall survival time was 7.7 months (95% CI: 7.2-12.6 months). The 1-year survival rate observed was 29% (95% CI: 15-45%). Grade 3/4 neutropenia and thrombocytopenia was observed in 5 (15%) and 4 (12%) patients, respectively. Two patients developed febrile neutropenia including one patient who died of neutropenic sepsis. Grade 3/4 nonhematologic observed were: sensory neuropathy in eight patients (24%); and hyperglycemia, malaise and nausea were all observed in four patients (12%). Cancer and Leukemia Group B will not pursue further investigation of paclitaxel and cisplatin due to the modest activity and the toxicity observed on this trial.

  17. Quantum-Chemical ab initio Calculations on the Three Isomers of Diborabenzene (C4H4B2)

    Science.gov (United States)

    Singh, Jaswinder; Wang, Yuekui; Raabe, Gerhard

    2010-01-01

    Quantum-chemical ab initio calculations up to the ZPE+CCSD(T)/aug-cc-pVTZ//MP2/6- 311++G** level were performed on three possible structural isomers of diborabenzene (C4H4B2). All three molecules were found to be local minima on the C4H4B2 energy surface and to have closed shell singlet ground states. While the ground states of the 1,3- and 1,4-isomer are planar and of C2v and D2h symmetry, respectively, 1,2-diborabenzene is non-planar with a C2 axis passing through the center of the BB bond and the middle of the opposite carbon-carbon bond as the only symmetry element. The energetically most favourable 1,3-diborabenzene was found to be about 19 and 36 kcal/mol lower in energy than the 1,2- and the 1,4-isomer. Planar 1,3- and 1,4-diborabenzene have three doubly occupied π orbitals while non-planar 1,2-diborabenzene has also three doubly occupied orbitals which can be derived from the π orbitals of its 3.7 kcal/mol energetically less favourable planar form ("π-like" orbitals). The lowest unoccupied orbitals of all three isomers have σ symmetry with large coefficients at the two boron atoms. These orbitals are lower in energy than the lowest unoccupied molecular orbitals (LUMOs) of e. g. benzene and pyridine and might cause pronounced acceptor properties which could be one of the reasons for the elusiveness of the title compounds. The results of bond separation reactions show that cyclic conjugation stabilizes all three diborabenzenes relative to their isolated fragments. The most effective stabilization energy of about 24 kcal/mol was found for the energetically lowest 1,3-isomer. This value amounts to approximately one third of the experimental value for the bond separation energy of pyridine. In all cases the energetically lowest triplet states are significantly (16 - 24 kcal/mol) higher in energy than the singlet ground states. Also among the triplets the 1,3-isomer is the energetically most fabourable species.

  18. Hydration structure and dynamics of a hydroxide ion in water clusters of varying size and temperature: Quantum chemical and ab initio molecular dynamics studies

    International Nuclear Information System (INIS)

    Bankura, Arindam; Chandra, Amalendu

    2012-01-01

    Highlights: ► A theoretical study of hydroxide ion-water clusters is carried for varying cluster size and temperature. ► The structures of OH − (H 2 O) n are found out through quantum chemical calculations for n = 4, 8, 16 and 20. ► The finite temperature behavior of the clusters is studied through ab initio dynamical simulations. ► The spectral features of OH modes (deuterated) and their dependence on hydrogen bonding states of water are discussed. ► The mechanism and kinetics of proton transfer processes in these anionic clusters are also investigated. - Abstract: We have investigated the hydration structure and dynamics of OH − (H 2 O) n clusters (n = 4, 8, 16 and 20) by means of quantum chemical and ab initio molecular dynamics calculations. Quantum chemical calculations reveal that the solvation structure of the hydroxide ion transforms from three and four-coordinated surface states to five-coordinated interior state with increase in cluster size. Several other isomeric structures with energies not very different from the most stable isomer are also found. Ab initio simulations show that the most probable configurations at higher temperatures need not be the lowest energy isomeric structure. The rates of proton transfer in these clusters are found to be slower than that in bulk water. The vibrational spectral calculations reveal distinct features for free OH (deuterated) stretch modes of water in different hydrogen bonding states. Effects of temperature on the structural and dynamical properties are also investigated for the largest cluster considered here.

  19. Ferrocene-based diradicals of imino nitroxide, nitronyl nitroxide and verdazyl, and their cations are possible SMM: A quantum chemical study

    Science.gov (United States)

    Pal, Arun K.; Datta, Sambhu N.

    2017-05-01

    Six diradicals designed from imino nitroxide, verdazyl and nitronyl nitroxide monoradicals coupled via the ferrocene moiety and six corresponding triradical cations are quantum chemically investigated. The transoid conformation is employed for considerations of general stability. All biradicals are found as very weakly and antiferromagnetically coupled. This agrees with experiment. The cations have strong antiferromagnetic spin-coupling. The charge and spin population distributions, spin alternation pattern, and the disjoint nature of SOMOs can be used to explain the nature and extent of magnetic interaction. Calculated EPR characteristics identify the neutral species as well as their cations as possible single molecule magnets.

  20. Quantum Chemical and FTIR Spectroscopic Studies on the Linkage Isomerism of Carbon Monoxide in Alkali-Metal-Exchanged Zeolites: A Review of Current Research

    OpenAIRE

    E. Garrone; A. A. Tsyganenko; G. Turnes Palomino; C. Otero Areán

    2002-01-01

    Abstract: When adsorbed (at a low temperature) on alkali-metal-exchanged zeolites, CO forms both M(CO)+ and M(OC)+ carbonyl species with the extra-framework alkali-metal cation of the zeolite. Both quantum chemical and experimental results show that C-bondend adducts are characterized by a C−O stretching IR band at a frequency higher than that of 2143 cm-1 for free CO, while for O-bonded adducts this IR band appears below 2143 cm-1. The cation-CO interaction energy is higher for M(CO)+ t...

  1. The electronic structure of VO in its ground and electronically excited states: A combined matrix isolation and quantum chemical (MRCI) study

    International Nuclear Information System (INIS)

    Hübner, Olaf; Hornung, Julius; Himmel, Hans-Jörg

    2015-01-01

    The electronic ground and excited states of the vanadium monoxide (VO) molecule were studied in detail. Electronic absorption spectra for the molecule isolated in Ne matrices complement the previous gas-phase spectra. A thorough quantum chemical (multi-reference configuration interaction) study essentially confirms the assignment and characterization of the electronic excitations observed for VO in the gas-phase and in Ne matrices and allows the clarification of open issues. It provides a complete overview over the electronically excited states up to about 3 eV of this archetypical compound

  2. Benefits of extensive recruitment effort persist during follow-ups and are consistent across age group and survey method. the TRAILS study

    NARCIS (Netherlands)

    E. Nederhof (Esther); F. Jörg (Frederike); D. Raven (Dennis); R. Veenstra (René); F.C. Verhulst (Frank); J. Ormel (Johan Hans); A.J. Oldehinkel (Albertine)

    2012-01-01

    textabstractBackground: Extensive recruitment effort at baseline increases representativeness of study populations by decreasing non-response and associated bias. First, it is not known to what extent increased attrition occurs during subsequent measurement waves among subjects who were

  3. IR spectroscopy and quantum-chemical studies on the binding and activation of CO on metal catalysts. IR-spektroskopische und quantenmechanische Untersuchungen zur Bindung und Aktivierung von Kohlenmonoxid an Metallkatalysatoren

    Energy Technology Data Exchange (ETDEWEB)

    Miessner, H.

    1988-05-04

    The present study is concerned with the investigation of the interaction and activation of CO with metal carrier catalysts. In connection with the catalytic investigations on the generation of oxygenous products from synthesis gas or methanol, attention was directed mainly to rhodium carrier catalysts. The aim of the investigations was to characterise the rhodium catalysts, which, during CO hydrogenation, occupy an exceptional position among the metals of the 8th auxiliary group, and which show a special selectivity with respect to oxygenous C{sub 2}{sup +} products. Since the influence of the carrier is of a decisive importance in this connection, a whole lot of carriers were incorporated in the study: Al{sub 2}O{sub 3}, SiO{sub 2}, TiO{sub 2}, ZnO, MgO, X and Y zeolites with different Si:Al ratios of 1.1-100. To solve the problems mentioned, IR spectroscopy, particularly with the help of CO as a probe molecule, and quantum-chemical model calculations were applied. For interpretation purposes, the results of catalytic CO hydrogenation and of methanol carbonylation as well as of further physico-chemical investigation methods such as temperature-programmed reduction, the chemisorption of hydrogen and CO and the temperature-programmed desorption of CO were consulted. (orig./EF).

  4. Conformational and structural analysis of 2-allyl-1,2-benzisothiazol-3(2 H)-one 1,1-dioxide as probed by matrix-isolation spectroscopy and quantum chemical calculations

    Science.gov (United States)

    Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Coelho, Daniela; Cristiano, M. Lurdes S.; Fausto, Rui

    2009-02-01

    2-Allyl-1,2-benzisothiazol-3(2 H)-one 1,1-dioxide (ABIOD) has been studied by matrix-isolation infrared spectroscopy and quantum chemical calculations. A conformational search on the B3LYP/6 -311++G(3df,3pd) potential energy surface of the molecule demonstrated the existence of three conformers, Sk, Sk' and C, with similar energies, differing in the orientation of the allyl group. The calculations predicted the Sk form as the most stable in the gaseous phase, whereas the Sk' and C conformers have calculated relative energies of ca. 0.6 and 0.8-3.0 kJ mol -1, respectively (depending on the level of theory). In agreement with the relatively large (>6 kJ mol -1) calculated barriers for conformational interconversion, the three conformers could be efficiently trapped in an argon matrix at 10 K, the experimental infrared spectrum of the as-deposited matrix fitting well the simulated spectrum built from the calculated spectra for individual conformers scaled by their predicted populations at the temperature of the vapour of the compound prior to matrix deposition. Upon annealing the matrix at 24 K, however, both Sk and Sk' conformers were found to convert to the more polar C conformer, indicating that this latter form becomes the most stable ABIOD conformer in the argon matrix.

  5. Hydrophobic fluorine mediated switching of the hydrogen bonding site as well as orientation of water molecules in the aqueous mixture of monofluoroethanol: IR, molecular dynamics and quantum chemical studies.

    Science.gov (United States)

    Mondal, Saptarsi; Biswas, Biswajit; Nandy, Tonima; Singh, Prashant Chandra

    2017-09-20

    The local structures between water-water, alcohol-water and alcohol-alcohol have been investigated for aqueous mixtures of ethanol (ETH) and monofluoroethanol (MFE) by the deconvolution of IR bands in the OH stretching region, molecular dynamics simulation and quantum chemical calculations. It has been found that the addition of a small amount of ETH into the aqueous medium increases the strength of the hydrogen bonds between water molecules. In an aqueous mixture of MFE, the substitution of a single fluorine induces a change in the orientation as well as the hydrogen bonding site of water molecules from the oxygen to the fluorine terminal of MFE. The switching of the hydrogen bonding site of water in the aqueous mixture of MFE results in comparatively strong hydrogen bonds between MFE and water molecules as well as less clustering of water molecules, unlike the case of the aqueous mixture of ETH. These findings about the modification of a hydrogen bond network by the hydrophobic fluorine group probably make fluorinated molecules useful for pharmaceutical as well as biological applications.

  6. Cation solvation with quantum chemical effects modeled by a size-consistent multi-partitioning quantum mechanics/molecular mechanics method.

    Science.gov (United States)

    Watanabe, Hiroshi C; Kubillus, Maximilian; Kubař, Tomáš; Stach, Robert; Mizaikoff, Boris; Ishikita, Hiroshi

    2017-07-21

    In the condensed phase, quantum chemical properties such as many-body effects and intermolecular charge fluctuations are critical determinants of the solvation structure and dynamics. Thus, a quantum mechanical (QM) molecular description is required for both solute and solvent to incorporate these properties. However, it is challenging to conduct molecular dynamics (MD) simulations for condensed systems of sufficient scale when adapting QM potentials. To overcome this problem, we recently developed the size-consistent multi-partitioning (SCMP) quantum mechanics/molecular mechanics (QM/MM) method and realized stable and accurate MD simulations, using the QM potential to a benchmark system. In the present study, as the first application of the SCMP method, we have investigated the structures and dynamics of Na + , K + , and Ca 2+ solutions based on nanosecond-scale sampling, a sampling 100-times longer than that of conventional QM-based samplings. Furthermore, we have evaluated two dynamic properties, the diffusion coefficient and difference spectra, with high statistical certainty. Furthermore the calculation of these properties has not previously been possible within the conventional QM/MM framework. Based on our analysis, we have quantitatively evaluated the quantum chemical solvation effects, which show distinct differences between the cations.

  7. Approximate quantum chemical methods for modelling carbohydrate conformation and aromatic interactions: β-cyclodextrin and its adsorption on a single-layer graphene sheet.

    Science.gov (United States)

    Jaiyong, Panichakorn; Bryce, Richard A

    2017-06-14

    Noncovalent functionalization of graphene by carbohydrates such as β-cyclodextrin (βCD) has the potential to improve graphene dispersibility and its use in biomedical applications. Here we explore the ability of approximate quantum chemical methods to accurately model βCD conformation and its interaction with graphene. We find that DFTB3, SCC-DFTB and PM3CARB-1 methods provide the best agreement with density functional theory (DFT) in calculation of relative energetics of gas-phase βCD conformers; however, the remaining NDDO-based approaches we considered underestimate the stability of the trans,gauche vicinal diol conformation. This diol orientation, corresponding to a clockwise hydrogen bonding arrangement in the glucosyl residue of βCD, is present in the lowest energy βCD conformer. Consequently, for adsorption on graphene of clockwise or counterclockwise hydrogen bonded forms of βCD, calculated with respect to this unbound conformer, the DFTB3 method provides closer agreement with DFT values than PM7 and PM6-DH2 approaches. These findings suggest approximate quantum chemical methods as potentially useful tools to guide the design of carbohydrate-graphene interactions, but also highlights the specific challenge to NDDO-based methods in capturing the relative energetics of carbohydrate hydrogen bond networks.

  8. The Bero Volganic Group: New Lithological, Stratigraphic, and Geochemical Data of this Extension of the Parana-Etendeka Igneous Province into SW Angola with Implications

    Science.gov (United States)

    Marsh, J.; Swart, R.

    2015-12-01

    The Bero Volcanic Group, an extension of the Etendeka-Paraná Igneous Province into SW Angola, forms the eroded basement to the on-shore Namibe Basin, an Early Cretaceous-Cenozoic terrestrial and marine sedimentary sequence. The igneous suite outcrops between latitudes 14.68o and 15.25o S and comprises quartz latite rheoignimbrites/lavas, tholeiitic basaltic lavas, pyroclastic/volcaniclastic deposits, minor aeolian sandstones, and mafic tholeiitic dykes and gabbroic sheets. Quartz latite lithologies dominate. In the Rio Bero area in the S quartz latites are underlain by several thin flows of basalt interbedded with, and underlain by, thin discontinuous lenses of aeolian sandstone. This sequence is consistent with the general stratigraphic sequence in the northern Etendeka of Namibia. To the N basalts and aeolian sandstones are absent and the quartz latites lie directly on Precambrian basement rocks in places. To date, data for a quartz latite correlated with a Chapecó rhyolites of the Paraná are available from only one locality in Angola. This study's wider sampling and major and trace element and radiogenic isotope analysis reveals the following: (1) all mafic rocks are high-Ti, the lavas being equivalent to the Khumiba/Urubici type; (2) mafic dykes cutting the quartz latites having affinities to the Paranapanema-Ribeira mafic lavas; (3) five quartz latite geochemical types are present, three of which are known from Etendeka/Paraná (Sarusas/Guarapuava, Khoraseb/Ourinhos and Ventura) and their stratigraphic relationships in Angola are consistent with those in the Etendeka and Paraná; (4) their Angolan occurrence significantly extends the area covered by, and potential eruptive volumes of, these silicic types; (5) two other quartz latite types are unknown in the Etendeka and Paraná and are probably products of low-volume, local eruptions. The Chinguau type is geochemically similar to the low-Ti quartz lalites of the southern Etendeka but has lower Epsilon Nd

  9. Isolation, characterization, spectroscopic properties and quantum chemical computations of an important phytoalexin resveratrol as antioxidant component from Vitis labrusca L. and their chemical compositions

    Science.gov (United States)

    Güder, Aytaç; Korkmaz, Halil; Gökce, Halil; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2014-12-01

    In this study, isolation and characterization of trans-resveratrol (RES) as an antioxidant compound were carried out from VLE, VLG and VLS. Furthermore, antioxidant activities were evaluated by using six different methods. Finally, total phenolic, flavonoid, ascorbic acid, anthocyanin, lycopene, β-carotene and vitamin E contents were carried out. In addition, the FT-IR, 13C and 1H NMR chemical shifts and UV-vis. spectra of trans-resveratrol were experimentally recorded. Quantum chemical computations such as the molecular geometry, vibrational frequencies, UV-vis. spectroscopic parameters, HOMOs-LUMOs energies, molecular electrostatic potential (MEP), natural bond orbitals (NBO) and nonlinear optics (NLO) properties of title molecule have been calculated by using DFT/B3PW91 method with 6-311++G(d,p) basis set in ground state for the first time. The obtained results show that the calculated spectroscopic data are in a good agreement with experimental data.

  10. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

    Directory of Open Access Journals (Sweden)

    Ambrish Singh

    2015-08-01

    Full Text Available The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphyrin (HPTB, 5,10,15,20-tetra(4-pyridyl-21H,23H-porphyrin (T4PP, 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayltetrakis(benzoic acid (THP and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP was studied using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization, scanning electrochemical microscopy (SECM and scanning electron microscopy (SEM techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  11. Assessing the Utility of the Nominal Group Technique as a Consensus-Building Tool in Extension-Led Avian Influenza Response Planning

    Science.gov (United States)

    Kline, Terence R.

    2013-01-01

    The intent of the project described was to apply the Nominal Group Technique (NGT) to achieve a consensus on Avian Influenza (AI) planning in Northeastern Ohio. Nominal Group Technique is a process first developed by Delbecq, Vande Ven, and Gustafsen (1975) to allow all participants to have an equal say in an open forum setting. A very diverse…

  12. Molecular structure, vibrational spectra and quantum chemical MP2/DFT studies toward the rational design of hydroxyurea imprinted polymer

    Science.gov (United States)

    Prasad, Bhim Bali; Rai, Garima

    2013-03-01

    In this study, both experimental and theoretical vibrational spectra of template (hydroxyurea, HU), monomer (N-(4,6-bisacryloyl amino-[1,3,5] triazine-2-yl-)-acryl amide, TAT), and HU-TAT complexes were compared and these were respectively found to be in good agreement. Binding energies of HU, when complexed with different monomers, were computed using second order Moller Plesset theory (MP2) at 6-311++G(d,p) level both in the gas as well as solution phases. HU is an antineoplastic agent extensively being used in the treatment of polycythaemia Vera and thrombocythemia. It is also used to reduce the frequency of painful attacks in sickle cell anemia. It has antiretroviral property in disease like AIDS. All spectral characterizations were made using Density Functional Theory (DFT) at B3LYP employing 6-31+g(2d, 2p) basis set. The theoretical values for 13C and 1H NMR chemical shifts were found to be in accordance with the corresponding experimental values. Of all different monomers studied for the synthesis of molecularly imprinted polymer (MIP) systems, the monomer TAT (2 mol) was typically found to have a best binding score requisite for complexation with HU (1 mol) at the ground state.

  13. The synergistic inhibitive effect and some quantum chemical parameters of 2,3-diaminonaphthalene and iodide ions on the hydrochloric acid corrosion of aluminium

    International Nuclear Information System (INIS)

    Obot, I.B.; Obi-Egbedi, N.O.; Umoren, S.A.

    2009-01-01

    The effect of iodide ions on the inhibitive performance of 2,3-diaminonaphthalene (2,3-DAN) in 1 M HCl for aluminium corrosion has been studied using hydrogen evolution (gasometry) measurements at 30 and 40 deg. C. Results obtained showed that the presence of 2,3-DAN molecules in the corrosive medium (1 M HCl solution) inhibits the corrosion process of aluminium and as the concentration of 2,3-DAN increases the inhibition efficiency also increased at the studied temperatures. A synergistic effect was observed between KI and 2,3-DAN. The experimental results suggest that the presence of iodide ions in the solutions stabilized the adsorption of 2,3-DAN molecules on the metal surfaces and, therefore improve the inhibition efficiency of 2,3-DAN. Phenomenon of physical adsorption is proposed for the inhibition and the process followed the Freundlich adsorption isotherm. The activation energy (E a ), heat of adsorption (Q ads ) and free energy of adsorption for the corrosion process (ΔG ads ) have been evaluated at the different temperatures and the values support the results obtained. Some quantum chemical parameters and the Mulliken charge densities for 2,3-diaminonaphthalene were calculated by the AM1 Semi-empirical method to provide further insight into the mechanism of inhibition of the corrosion process

  14. An investigation on the structure, spectroscopy and thermodynamic aspects of Br2((-))(H2O)n clusters using a conjunction of stochastic and quantum chemical methods.

    Science.gov (United States)

    Naskar, Pulak; Chaudhury, Pinaki

    2016-06-28

    In this work we obtained global as well as local structures of Br2((-))(H2O)n clusters for n = 2 to 6 followed by the study of IR-spectral features and thermochemistry for the structures. The way adopted by us to obtain structures is not the conventional one used in most cases. Here we at first generated excellent quality pre-optimized structures by exploring the suitable empirical potential energy surface using stochastic optimizer simulated annealing. These structures are then further refined using quantum chemical calculations to obtain the final structures, and spectral and thermodynamic features. We clearly showed that our approach results in very quick and better convergence which reduces the computational cost and obviously using the strategy we are able to get one [i.e. global] or more than one [i.e. global and local(s)] energetically lower structures than those which are already reported for a given cluster size. Moreover, IR-spectral results and the evolutionary trends in interaction energy, solvation energy and vertical detachment energy for global structures of each size have also been presented to establish the utility of the procedure employed.

  15. Quantum chemical modeling of new derivatives of (E,E)-azomethines: Synthesis, spectroscopic (FT-IR, UV/Vis, polarization) and thermophysical investigations

    Science.gov (United States)

    Shahab, Siyamak; Sheikhi, Masoome; Filippovich, Liudmila; Anatol'evich, Dikusar Evgenij; Yahyaei, Hooriye

    2017-06-01

    In the present work, the molecular structures of three new azomethine dyes: N-benzylidene-4-((E)-phenyldiazenyl)aniline (PAZB-1), 2-methoxy-4-(((4-((E)- phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-2) and 2-methoxy-5-((E)-((4-((E)- phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-8) have been predicted and investigated using Density Functional Theory (DFT) in dimethylformamide (DMF). The geometries of the azomethine dyes were optimized by PBE0/6-31 + G* level of theory. The electronic spectra of these azomethine dyes in a DMF solution was carried out by TDPBE0/6-31 + G* method. After quantum-chemical calculations three new azomethine dyes for optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. The computed absorption spectral data of the azomethine dyes are in good agreement with the experimental data, thus allowing an assignment of the UV/Vis spectra. On the basis of polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films for Visible region of spectrum were developed. The main optical parameters of polarizing PVA-films (Transmittance, Polarization Efficiency and Dichroic Ratio) have been measured and discussed. Anisotropy of thermal conductivity of the PVA-films has been studied.

  16. Combined quantum chemical density functional theory and spectroscopic Raman and UV-vis-NIR study of oligothienoacenes with five and seven rings.

    Science.gov (United States)

    Osuna, Reyes Malavé; Zhang, Xinnan; Matzger, Adam Jay; Hernandez, Víctor; López Navarrete, Juan Teodomiro

    2006-04-20

    In this article, we report the characterization of novel oligothienoacenes with five and seven fused thiophene rings, materials with potential applications in organic electronics. In contrast to usual alpha-linked oligothiophenes, these fused oligothiophenes have a larger band gap than most semiconductors currently used in the fabrication of organic field-effect transistors (OFETs) and therefore they are expected to be more stable in air. The synthesis of these fused-ring oligomers was motivated by the notion that a more rigid and planar structure should reduce defects (such as torsion about single bonds between alpha-linked units or S-syn defects) and thus improve conjugation for better charge-carrier mobility. The conjugational properties of these two molecular materials have been investigated by means of FT-Raman spectroscopy, revealing that conjugation still increases in passing from the five-ring oligomer to that with seven-rings. DFT and TDDFT quantum chemical calculations have been performed, at the B3LYP/6-31G level, to assess information regarding the minimum-energy molecular structure, topologies, and absolute energies of the frontier molecular orbitals (MOs.) around the gap, vibrational normal modes related to the main Raman features, and vertical one-electron excitations giving rise to the main optical absorptions.

  17. Comparison of reactivity on step and terrace sites of Pd (3 3 2) surface for the dissociative adsorption of hydrogen: A quantum chemical molecular dynamics study

    International Nuclear Information System (INIS)

    Ahmed, Farouq; Nagumo, Ryo; Miura, Ryuji; Ai, Suzuki; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Miyamoto, Akira

    2011-01-01

    The notion of 'active sites' is fundamental to heterogeneous catalysis. However, the exact nature of the active sites, and hence the mechanism by which they act, are still largely a matter of speculation. In this study, we have presented a systematic quantum chemical molecular dynamics (QCMD) calculations for the interaction of hydrogen on different step and terrace sites of the Pd (3 3 2) surface. Finally the dissociative adsorption of hydrogen on step and terrace as well as the influence of surface hydrogen vacancy for the dissociative adsorption of hydrogen has been investigated through QCMD. This is a state-of-the-art method for calculating the interaction of atoms and molecules with metal surfaces. It is found that fully hydrogen covered (saturated) step sites can dissociate hydrogen moderately and that a monovacancy surface is suitable for significant dissociative adsorption of hydrogen. However in terrace site of the surface we have found that dissociation of hydrogen takes place only on Pd sites where the metal atom is not bound to any pre-adsorbed hydrogen atoms. Furthermore, from the molecular dynamics and electronic structure calculations, we identify a number of consequences for the interpretation and modeling of diffusion experiments demonstrating the coverage and directional dependence of atomic hydrogen diffusion on stepped palladium surface.

  18. Quantum Chemical and FTIR Spectroscopic Studies on the Linkage Isomerism of Carbon Monoxide in Alkali-Metal-Exchanged Zeolites: A Review of Current Research

    Directory of Open Access Journals (Sweden)

    E. Garrone

    2002-07-01

    Full Text Available Abstract: When adsorbed (at a low temperature on alkali-metal-exchanged zeolites, CO forms both M(CO+ and M(OC+ carbonyl species with the extra-framework alkali-metal cation of the zeolite. Both quantum chemical and experimental results show that C-bondend adducts are characterized by a C−O stretching IR band at a frequency higher than that of 2143 cm-1 for free CO, while for O-bonded adducts this IR band appears below 2143 cm-1. The cation-CO interaction energy is higher for M(CO+ than for M(OC+ carbonyls, although the corresponding difference decreases substantially when going from Li+ to Cs+. By means of variable-temperature FTIR spectroscopy, this energy difference was determined for several alkali-metal cations, and the existence of a thermal equilibrium between M(CO+ and M(OC+ species was established. The current state of research in this field is reviewed here, with a view to gain more insight into the thermal isomerization process.

  19. Theoretical description of copper Cu(I)/Cu(II) complexes in mixed ammine-aqua environment. DFT and ab initio quantum chemical study

    International Nuclear Information System (INIS)

    Pavelka, Matej; Burda, Jaroslav V.

    2005-01-01

    This work is devoted to investigate the interactions of the Cu(I)/Cu(II) cation with variable ammonia-water ligand field by the quantum chemical approach. For that purpose, the optimization of the [Cu(NH 3 ) m (H 2 O) n ] 2+/+ complexes (where n varies from 0 to 4 or 6 and m + n = 4 or 6) has been performed at the DFT/6-31+G(d) level of theory in conjunction with the B3PW91 hybrid functional. Based on the results of the single-point B3LYP/6-311++G(2df,2pd) calculations, the stabilization energies were determined. The two-coordinated copper(I) complexes appeared to be the most stable compounds with the remaining water or ammonia molecules in the second solvation shell. In the case of the Cu(II) systems, four-coordinated complexes were found to be the most stable. In order to examine and explain bonding characteristics, Morokuma interaction energy decomposition (for selected Cu + complexes) and Natural Population Analysis for all systems were performed. It was found that the most stable structures correlate with the highest donation effects. Therefore, more polarizable ammonia molecules exhibit higher donation than water and thus make stronger bonds to copper. This can be demonstrated by the fact that the NH 3 molecule always tries to occupy the first solvation shell in mixed ammine-aqua complexes

  20. Quantum chemical study of the structure, spectroscopy and reactivity of NO+.(H2O)n=1-5 clusters

    Science.gov (United States)

    Linton, Kirsty A.; Wright, Timothy G.; Besley, Nicholas A.

    2018-03-01

    Quantum chemical methods including Møller-Plesset perturbation (MP2) theory and density functional theory (DFT) have been used to study the structure, spectroscopy and reactivity of NO+.(H2O)n=1-5 clusters. MP2/6-311++G** calculations are shown to describe the structure and spectroscopy of the clusters well. DFT calculations with exchange-correlation functionals with a low fraction of Hartree-Fock exchange give a binding energy of NO+.(H2O) that is too high and incorrectly predict the lowest energy structure of NO+.(H2O)2, and this error may be associated with a delocalization of charge onto the water molecule directly binding to NO+. Ab initio molecular dynamics (AIMD) simulations were performed to study the NO+.(H2O)5 H+.(H2O)4 + HONO reaction to investigate the formation of HONO from NO+.(H2O)5. Whether an intracluster reaction to form HONO is observed depends on the level of electronic structure theory used. Of note is that methods that accurately describe the relative energies of the product and reactant clusters did not show reactions on the timescales studied. This suggests that in the upper atmosphere the reaction may occur owing to the energy present in the NO+.(H2O)5 complex following its formation. This article is part of the theme issue `Modern theoretical chemistry'.

  1. Exploration of bulk and interface behavior of gas molecules and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid using equilibrium and nonequilibrium molecular dynamics simulation and quantum chemical calculation.

    Science.gov (United States)

    Yang, Quan; Achenie, Luke E K

    2018-04-18

    Ionic liquids (ILs) show brilliant performance in separating gas impurities, but few researchers have performed an in-depth exploration of the bulk and interface behavior of penetrants and ILs thoroughly. In this research, we have performed a study on both molecular dynamics (MD) simulation and quantum chemical (QC) calculation to explore the transport of acetylene and ethylene in the bulk and interface regions of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]-[BF4]). The diffusivity, solubility and permeability of gas molecules in the bulk were researched with MD simulation first. The subdiffusion behavior of gas molecules is induced by coupling between the motion of gas molecules and the ions, and the relaxation processes of the ions after the disturbance caused by gas molecules. Then, QC calculation was performed to explore the optical geometry of ions, ion pairs and complexes of ions and penetrants, and interaction potential for pairs and complexes. Finally, nonequilibrium MD simulation was performed to explore the interface structure and properties of the IL-gas system and gas molecule behavior in the interface region. The research results may be used in the design of IL separation media.

  2. Quantum chemical calculations and spectroscopic measurements of spectroscopic and thermodynamic properties of given uranyl complexes in aqueous solutions with possible environmental and industrial applications

    Directory of Open Access Journals (Sweden)

    Višňak Jakub

    2016-01-01

    Full Text Available A brief introduction into computational methodology and preliminary results for spectroscopic (excitation energies, vibrational frequencies in ground and excited electronic states and thermodynamic (stability constants, standard enthalpies and entropies of complexation reactions properties of some 1:1, 1:2 and 1:3 uranyl sulphato- and selenato- complexes in aqueos solutions will be given. The relativistic effects are included via Effective Core Potential (ECP, electron correlation via (TDDFT/B3LYP (dispersion interaction corrected and solvation is described via explicit inclusion of one hydration sphere beyond the coordinated water molecules. We acknowledge limits of this approximate description – more accurate calculations (ranging from semi-phenomenological two-component spin-orbit coupling up to four-component Dirac-Coulomb-Breit hamiltonian and Molecular Dynamics simulations are in preparation. The computational results are compared with the experimental results from Time-resolved Laser-induced Fluorescence Spectroscopy (TRLFS and UV-VIS spectroscopic studies (including our original experimental research on this topic. In case of the TRLFS and UV-VIS speciation studies, the problem of complex solution spectra decomposition into individual components is ill-conditioned and hints from theoretical chemistry could be very important. Qualitative agreement between our quantum chemical calculations of the spectroscopic properties and experimental data was achieved. Possible applications for geochemical modelling (e.g. safety studies of nuclear waste repositories, modelling of a future mining site and analytical chemical studies (including natural samples are discussed.

  3. Understanding Am3+/Cm3+ separation with H4TPAEN and its hydrophilic derivatives: a quantum chemical study.

    Science.gov (United States)

    Huang, Pin-Wen; Wang, Cong-Zhi; Wu, Qun-Yan; Lan, Jian-Hui; Song, Gang; Chai, Zhi-Fang; Shi, Wei-Qun

    2018-05-10

    Am3+/Cm3+ separation is an extremely hard but important task in nuclear waste treatment. In this study, Am and Cm complexes formed with a back-extraction agent N,N,N',N'-tetrakis[(6-carboxypyridin-2-yl)methyl]ethylene-diamine (H4TPAEN) and its two derivatives with hydrophilic substituents (methoxy and morpholine groups) were investigated using the density functional theory (DFT). The optimized geometrical structures indicated that the Am3+ cation matched better with the cavities of the three studied ligands than Cm3+, and the Am3+ cations were located deeper in the cavities of the ligands. The bond order and quantum theory of atoms in molecules (QTAIM) analyses suggested that ionic interactions dominated An-N and An-O (An = Cm and Am) bonds. However, weak and different extents of partial covalency could also be found in the Am-N and Cm-N bonds. The O donor atoms in the carboxylate groups preferably coordinated with Cm3+ rather than Am3+, whereas the N atoms preferred Am3+. Therefore, the Am3+/Cm3+ selectivity of H4TPAEN and its two hydrophilic derivatives may be ascribed to the competition between the An-N and An-O interactions and the few dissimilarities in their geometrical structures. Based on our calculations, the methoxy and morpholine groups in the two derivatives can serve as electron-donating groups and enhance the strength of the An-NPY bonds (NPY denotes the nitrogen atom of pyridine ring). When compared with the Am-complex, the Cm-complex exhibited significant strength effect, resulting in the relatively lower Am3+/Cm3+ separation ability of the H4TPAEN's hydrophilic derivatives.

  4. Quantum-chemical ab initio and B3LYP investigation of tricyanides and triisocyanides of Al, Ga, In

    International Nuclear Information System (INIS)

    Timoshkin, A.Yu.; Shefer, G.F.

    2000-01-01

    Ab initio and density functional B3LYP methods are used to obtain structural parameters, standard entropies and vibrational spectra of cyanides and isocyanides of trivalent Al, Ga, In for the first time. It is pointed out that for In cyanide form is more stable. There is divergence in data obtained in the framework of self-consistent field and by B3LYP methods what indicates importance of estimation of energy of electronic correlation and in the same time comparison of basic sets DZP and LANL2DZP demonstrates insufficiency of basic sets with effective potentials of skeleton for description molecular tricyanides of elements of the 3a group [ru

  5. Development of constraint algorithm for the number of electrons in molecular orbitals consisting mainly 4f atomic orbitals of rare-earth elements and its introduction to tight-binding quantum chemical molecular dynamics method

    International Nuclear Information System (INIS)

    Endou, Akira; Onuma, Hiroaki; Jung, Sun-ho

    2007-01-01

    Our original tight-binding quantum chemical molecular dynamics code, Colors', has been successfully applied to the theoretical investigation of complex materials including rare-earth elements, e.g., metal catalysts supported on a CeO 2 surface. To expand our code so as to obtain a good convergence for the electronic structure of a calculation system including a rare-earth element, we developed a novel algorithm to provide a constraint condition for the number of electrons occupying the selected molecular orbitals that mainly consist of 4f atomic orbitals of the rare-earth element. This novel algorithm was introduced in Colors. Using Colors, we succeeded in obtaining the classified electronic configurations of the 4f atomic orbitals of Ce 4+ and reduced Ce ions in a CeO 2 bulk model with one oxygen defect, which makes it difficult to obtain a good convergence using a conventional first-principles quantum chemical calculation code. (author)

  6. Dipicolinate salt of imidazole: Discovering its structure and properties using different experimental methodologies and quantum chemical investigations

    Science.gov (United States)

    Thirumurugan, R.; Anitha, K.

    2018-03-01

    A novel organic proton transfer complex of imidazolium dipicolinate (ID) has been synthesized and it was grown as single crystals using slow evaporation method. The molecular structure of synthesized compound and vibrational modes of its functional groups were confirmed by (1H and 13C) NMR, FTIR and FT-Raman spectroscopic studies, respectively. Single crystal X-ray diffraction (SCXRD) analysis confirmed the orthorhombic system with noncentrosymmetric (NCS), P212121, space group of grown ID crystal. UV-Vis-NIR spectral study confirmed its high optical transparency within the region of 285-1500 nm. Powder second harmonic generation (SHG) efficiency of ID crystal was confirmed and it was 6.8 times that of KDP crystal. TG-DTA and DSC analysis revealed the higher thermal stability of grown crystal as 249 °C. The dielectric response and mechanical behaviour of grown crystal were studied effectively. Density functional theory calculations were performed to probe the relationship between the structure and its properties including molecular optimization, Mulliken atomic charge distribution, frontier molecular orbital (FMOs) and molecular electrostatic potential map (MEP) analysis and first hyperpolarizability. All these experimental and computational results were discussed in this communication and it endorsed the ID compound as a potential NLO candidate could be employed in optoelectronics device applications in near future.

  7. The quantum-chemical modeling of structure and spectral characteristics for molecular complexes in system «penton-terlon»

    Directory of Open Access Journals (Sweden)

    Andrey V. Tokar

    2014-03-01

    Full Text Available The structure and spectral properties for molecular complexes, which formed by added monomer form of pentaplast as well as N-phenylbenzamide with some species of intermolecular interaction in system «penton-terlon» have been investigated at ab initio level of theory. It is shown, that the main contribution in total energy of molecules have included by dispersion forces, which realized between Chlorine atom of CH2Cl-group and Hydrogen atoms of benzene rings with amide fragment. The proposed theoretical models are validated in reflection of spectral and energetic characteristics of investigating system. Finally, the results of calculations are in good agreement with that data, which have been obtained for such type modeling previously.

  8. Prediction of pKa values for druglike molecules using semiempirical quantum chemical methods

    DEFF Research Database (Denmark)

    Jensen, Jan Halborg; Swain, Christopher J; Olsen, Lars

    2017-01-01

    Rapid yet accurate pKa prediction for druglike molecules is a key challenge in computational chemistry. This study uses PM6-DH+/COSMO, PM6/COSMO, PM7/COSMO, PM3/COSMO, AM1/COSMO, PM3/SMD, AM1/SMD, and DFTB3/SMD to predict the pKa values of 53 amine groups in 48 druglike compounds. The approach uses...... uncertainties of ±0.2-0.3 pH units, which make them statistically equivalent. However, for all but PM3/SMD and AM1/SMD the RMSEs are dominated by a single outlier, cefadroxil, caused by proton transfer in the zwitterionic protonation state. If this outlier is removed, the RMSE values for PM3/COSMO and AM1/COSMO...... drop to 1.0 ± 0.2 and 1.1 ± 0.3, whereas PM3/SMD and AM1/SMD remain at 1.5 ± 0.3 and 1.6 ± 0.3/0.4 pH units, making the COSMO-based predictions statistically better than the SMD-based predictions. For pKa calculations where a zwitterionic state is not involved or proton transfer in a zwitterionic state...

  9. A Quantum Chemical and Statistical Study of Phenolic Schiff Bases with Antioxidant Activity against DPPH Free Radical

    Directory of Open Access Journals (Sweden)

    El Hassane Anouar

    2014-04-01

    Full Text Available Phenolic Schiff bases are known as powerful antioxidants. To select the electronic, 2D and 3D descriptors responsible for the free radical scavenging ability of a series of 30 phenolic Schiff bases, a set of molecular descriptors were calculated by using B3P86 (Becke’s three parameter hybrid functional with Perdew 86 correlation functional combined with 6-31 + G(d,p basis set (i.e., at the B3P86/6-31 + G(d,p level of theory. The chemometric methods, simple and multiple linear regressions (SLR and MLR, principal component analysis (PCA and hierarchical cluster analysis (HCA were employed to reduce the dimensionality and to investigate the relationship between the calculated descriptors and the antioxidant activity. The results showed that the antioxidant activity mainly depends on the first and second bond dissociation enthalpies of phenolic hydroxyl groups, the dipole moment and the hydrophobicity descriptors. The antioxidant activity is inversely proportional to the main descriptors. The selected descriptors discriminate the Schiff bases into active and inactive antioxidants.

  10. FTIR, FT-Raman, FT-NMR, UV-visible and quantum chemical investigations of 2-amino-4-methylbenzothiazole.

    Science.gov (United States)

    Arjunan, V; Sakiladevi, S; Rani, T; Mythili, C V; Mohan, S

    2012-03-01

    The FT-IR (4000-400 cm(-1)) and FT-Raman (4000-100 cm(-1)) spectral measurements and complete assignments of the observed spectra of 2-amino-4-methylbenzothiazole (2A4MBT) have been proposed. Ab initio and DFT calculations have been performed and the structural parameters of the compound were determined from the optimised geometry with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities and Raman activities. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO, LUMO and band gap energies were measured by time-dependent DFT (TD-DFT) approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule. The influences of methyl and amino groups on the skeletal modes and on the proton chemical shifts have been investigated. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Structure and vibrational spectra of melaminium bis(trifluoroacetate) trihydrate: FT-IR, FT-Raman and quantum chemical calculations

    Science.gov (United States)

    Sangeetha, V.; Govindarajan, M.; Kanagathara, N.; Marchewka, M. K.; Gunasekaran, S.; Anbalagan, G.

    Melaminium bis(trifluoroacetate) trihydrate (MTFA), an organic material has been synthesized and single crystals of MTFA have been grown by the slow solvent evaporation method at room temperature. X-ray powder diffraction analysis confirms that MTFA crystal belongs to the monoclinic system with space group P2/c. The molecular geometry, vibrational frequencies and intensity of the vibrational bands have been interpreted with the aid of structure optimization based on density functional theory (DFT) B3LYP method with 6-311G(d,p) and 6-311++G(d,p) basis sets. The X-ray diffraction data have been compared with the data of optimized molecular structure. The theoretical results show that the crystal structure can be reproduced by optimized geometry and the vibrational frequencies show good agreement with the experimental values. The nuclear magnetic resonance (NMR) chemical shift of the molecule has been calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. HOMO-LUMO, and other related molecular and electronic properties are calculated. The Mulliken and NBO charges have also been calculated and interpreted.

  12. Quantum chemical studies on molecular structural conformations and hydrated forms of salicylamide and O-hydroxybenzoyl cyanide

    Science.gov (United States)

    Anandan, K.; Kolandaivel, P.; Kumaresan, R.

    Ab initio and density functional theory (DFT) methods have been employed to study the molecular structural conformations and hydrated forms of both salicylamide (SAM) and O-hydroxybenzoyl cyanide (OHBC). Molecular geometries and energetics have been obtained in the gaseous phase by employing the Møller-Plesset type 2 MP2/6-311G(2d,2p) and B3LYP/6-311G(2d,2p) levels of theory. The presence of an electron-releasing group (SAM) leads to an increase in the energy of the molecular system, while the presence of an electron-withdrawing group (OHBC) drastically decreases the energy. Chemical reactivity parameters (η and μ) have been calculated using the energy values of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) obtained at the Hartree-Fock (HF)/6-311G(2d,2p) level of theory for all the conformers and the principle of maximum hardness (MHP) has been tested. The condensed Fukui functions have been calculated using the atomic charges obtained through the natural bond orbital (NBO) analysis scheme for all the optimized structures at the B3LYP/6-311G(2d,2p) level of theory, and the most reactive sites of the molecules have been identified. Nuclear magnetic resonance (NMR) studies have been carried out at the B3LYP/6-311G(2d,2p) level of theory for all the conformers in the gaseous phase on the basis of the method of Cheeseman and coworkers. The calculated chemical shift values have been used to discuss the delocalization activity of the electron clouds. The dimeric structures of the most stable conformers of both SAM and OHBC in the gaseous phase have been optimized at the B3LYP/6-311G(2d,2p) level of theory, and the interaction energies have been calculated. The most stable conformers of both compounds bear an intramolecular hydrogen bond, which gives rise to the formation of a pseudo-aromatic ring. These conformers have been allowed to interact with the water molecule. Special emphasis has been given to analysis of the

  13. The Structure and Molecular Parameters of Camphene Determined by Fourier Transform Microwave Spectroscopy and Quantum Chemical Calculations

    Science.gov (United States)

    Neeman, Elias M.; Dréan, Pascal; Huet, T. R.

    2016-06-01

    The emission of volatile organic compounds, from plants has strong revelance for plant physiology, plant ecology and atmospheric chemistry. Camphene (C10H16) is a bicyclic monoterpene which is emitted in the atmosphere by biogenic sources. The structure of the unique stable conformer was optimized using density functional theory and ab initio calculations. The rotational spectrum of camphene was recorded in a supersonic jet expansion with a Fourier transform microwave spectrometer over the range 2-20 GHz. Signals from the parent species and from the ten 13C isotopomers were observed in natural abundance. The rotational and centrifugal distortion parameters were fitted to a Watson's Hamiltonian in the A-reduction. A magnetic hyperfine structure associated with the pairs of hydrogen nuclei in the methylene groups was observed and modeled.The rotational constants coupled to the equilibrium structure calculations were used to determine the r_0 and the r_m(1) gas-phase geometries of the carbon skeleton. The present work provides the first spectroscopic characterization of camphene in the gas phase and these results are also relevant for ozonolysis kinetics study through Criegee intermediates. R. Baraldi, F. Rapparini, O. Facini, D. Spano and P. Duce, Journal of Mediterranean Ecology, Vol.6, No.1, (2005). A. Bracho-Nunez, N. M. Knothe, S. Welter, M. Staudt, W. R. Costa, M. A. R. Liberato, M. T. F. Piedade, and J. Kesselmeier Biogeosciences, 10, 5855-5873, (2013). Minna Kivimäenpää, Narantsetseg Magsarjav, Rajendra Ghimire, Juha-Matti Markkanen, Juha Heijari, Martti Vuorinen and Jarmo K. Holopainen, Atmospheric Environment, 60, 477-485, (2012). R.C. de M. Oliveira and G. F. Bauerfeldt, J. Phys. Chem. A, 119 2802-2812 (2015)

  14. Structural analysis of ternary actinyl(V/VI) sorption complexes on gibbsite. A combined quantum chemical and spectroscopic approach

    Energy Technology Data Exchange (ETDEWEB)

    Gueckel, Katharina

    2013-10-08

    For the safety assessment of high-level nuclear waste repositories, it is mandatory to know the transportation paths of contaminants, e.g. actinyl ions, in the geological barrier. The most attention needs to be focused on the transport in aquifers, because water contamination, depending on retention and migration processes of radionuclides in the geosphere, is of primary environmental concern. The migration behavior of actinides in ground water is mainly controlled by aquatic speciations and sorption processes at water-mineral interfaces. Hence, the investigation of complexspecies in aqueous solutions and at mineral surfaces becomes essential for the safety assessment in the near and far field of nuclear repositories. For deep ground repositories, clay and clay minerals are considered as possible host rocks, because they show a low permeability and are expected to have a high retention capacity towards actinyl ions. But the complexity of naturally occurring minerals in particular their surface often hampers the unequivocal interpretation of results obtained from sorption experiments. The use of model phases only showing one particular functional group at the surfaces with a well defined surface topology is an appropriate approach for the understanding of the basic sorption processes. Aluminum oxide and hydroxides are of special interest because they represent main components in clays and clay minerals. In particular, gibbsite is widely used as a model system because it represents not only the most common crystalline aluminum hydroxide but also a ubiquitous weathering product of alumosilicates. Furthermore, the elemental structural unit of gibbsite, that is the Al(OH)6 octahedron, occurs ubiquitously as part of the structure of common clay minerals like kaolinite. In the present study, the sorption processes of U(VI) and Np(V) on gibbsite were studied under consideration of the aqueous speciation.

  15. On the isomers of pyridine-4-carboxaldoxime and its nitrate salt, X-ray crystal structure and quantum chemical calculations

    Science.gov (United States)

    Soliman, Saied M.; Albering, Jörg; Abu-Youssef, Morsy A. M.

    2017-07-01

    The reaction between nitric acid and pyridine-4-carboxaldoxime (P4A) afford the corresponding pyridinum nitrate salt (P4AN). Its X-ray structure is measured and compared with the related P4A salts. The DFT/B3LYP results showed that both the P4A and P4AN favored the Syn-I form which has the lowest energy among the other possible isomers. Transition state calculations predicted that the Syn-I form is the thermodynamically and kinetically most stable form. The X-ray solid state structure of the new nitrate salt (P4AN) indicated that the labile proton favored the N-atom of the pyridine ring. DFT studies showed that the same is true for its solution in polar solvents. In contrast, the pyridinium cation is not favored either in the gas phase or solution of P4AN in nonpolar solvent. In these cases, the proton favored to bond with one O-atom from the nitrate group. Second order interaction energies and Mayer bond order values revealed these results. The bond order of the Nsbnd H bond is higher in polar solvents as well as at the experimental structure than either in the gas phase or non polar solvents. The topology parameters obtained from the atoms in molecules (AIM) analysis were used to describe the nature of the Nsbnd H and Osbnd H bonds. The bond critical points (BCP) were found to be close to the H-atoms in case of stronger interaction.

  16. A 3D QSAR pharmacophore model and quantum chemical structure--activity analysis of chloroquine(CQ)-resistance reversal.

    Science.gov (United States)

    Bhattacharjee, Apurba K; Kyle, Dennis E; Vennerstrom, Jonathan L; Milhous, Wilbur K

    2002-01-01

    Using CATALYST, a three-dimensional QSAR pharmacophore model for chloroquine(CQ)-resistance reversal was developed from a training set of 17 compounds. These included imipramine (1), desipramine (2), and 15 of their analogues (3-17), some of which fully reversed CQ-resistance, while others were without effect. The generated pharmacophore model indicates that two aromatic hydrophobic interaction sites on the tricyclic ring and a hydrogen bond acceptor (lipid) site at the side chain, preferably on a nitrogen atom, are necessary for potent activity. Stereoelectronic properties calculated by using AM1 semiempirical calculations were consistent with the model, particularly the electrostatic potential profiles characterized by a localized negative potential region by the side chain nitrogen atom and a large region covering the aromatic ring. The calculated data further revealed that aminoalkyl substitution at the N5-position of the heterocycle and a secondary or tertiary aliphatic aminoalkyl nitrogen atom with a two or three carbon bridge to the heteroaromatic nitrogen (N5) are required for potent "resistance reversal activity". Lowest energy conformers for 1-17 were determined and optimized to afford stereoelectronic properties such as molecular orbital energies, electrostatic potentials, atomic charges, proton affinities, octanol-water partition coefficients (log P), and structural parameters. For 1-17, fairly good correlation exists between resistance reversal activity and intrinsic basicity of the nitrogen atom at the tricyclic ring system, frontier orbital energies, and lipophilicity. Significantly, nine out of 11 of a group of structurally diverse CQ-resistance reversal agents mapped very well on the 3D QSAR pharmacophore model.

  17. POSSIBLE NATURE OF THE RADIATION-INDUCED SIGNAL IN NAILS: HIGH-FIELD EPR, CONFIRMING CHEMICAL SYNTHESIS, AND QUANTUM CHEMICAL CALCULATIONS.

    Science.gov (United States)

    Tipikin, Dmitriy S; Swarts, Steven G; Sidabras, Jason W; Trompier, François; Swartz, Harold M

    2016-12-01

    Exposure of finger- and toe-nails to ionizing radiation generates an Electron Paramagnetic Resonance (EPR) signal whose intensity is dose dependent and stable at room temperature for several days. The dependency of the radiation-induced signal (RIS) on the received dose may be used as the basis for retrospective dosimetry of an individual's fortuitous exposure to ionizing radiation. Two radiation-induced signals, a quasi-stable (RIS2) and stable signal (RIS5), have been identified in nails irradiated up to a dose of 50 Gy. Using X-band EPR, both RIS signals exhibit a singlet line shape with a line width around 1.0 mT and an apparent g-value of 2.0044. In this work, we seek information on the exact chemical nature of the radiation-induced free radicals underlying the signal. This knowledge may provide insights into the reason for the discrepancy in the stabilities of the two RIS signals and help develop strategies for stabilizing the radicals in nails or devising methods for restoring the radicals after decay. In this work an analysis of high field (94 GHz and 240 GHz) EPR spectra of the RIS using quantum chemical calculations, the oxidation-reduction properties and the pH dependence of the signal intensities are used to show that spectroscopic and chemical properties of the RIS are consistent with a semiquinone-type radical underlying the RIS. It has been suggested that semiquinone radicals formed on trace amounts of melanin in nails are the basis for the RIS signals. However, based on the quantum chemical calculations and chemical properties of the RIS, it is likely that the radicals underlying this signal are generated from the radiolysis of L-3,4-dihydroxyphenylalanine (DOPA) amino acids in the keratin proteins. These DOPA amino acids are likely formed from the exogenous oxidation of tyrosine in keratin by the oxygen from the air prior to irradiation. We show that these DOPA amino acids can work as radical traps, capturing the highly reactive and unstable sulfur

  18. POSSIBLE NATURE OF THE RADIATION-INDUCED SIGNAL IN NAILS: HIGH-FIELD EPR, CONFIRMING CHEMICAL SYNTHESIS, AND QUANTUM CHEMICAL CALCULATIONS

    Science.gov (United States)

    Tipikin, Dmitriy S.; Swarts, Steven G.; Sidabras, Jason W.; Trompier, François; Swartz, Harold M.

    2016-01-01

    Exposure of finger- and toe-nails to ionizing radiation generates an Electron Paramagnetic Resonance (EPR) signal whose intensity is dose dependent and stable at room temperature for several days. The dependency of the radiation-induced signal (RIS) on the received dose may be used as the basis for retrospective dosimetry of an individual's fortuitous exposure to ionizing radiation. Two radiation-induced signals, a quasi-stable (RIS2) and stable signal (RIS5), have been identified in nails irradiated up to a dose of 50 Gy. Using X-band EPR, both RIS signals exhibit a singlet line shape with a line width around 1.0 mT and an apparent g-value of 2.0044. In this work, we seek information on the exact chemical nature of the radiation-induced free radicals underlying the signal. This knowledge may provide insights into the reason for the discrepancy in the stabilities of the two RIS signals and help develop strategies for stabilizing the radicals in nails or devising methods for restoring the radicals after decay. In this work an analysis of high field (94 GHz and 240 GHz) EPR spectra of the RIS using quantum chemical calculations, the oxidation–reduction properties and the pH dependence of the signal intensities are used to show that spectroscopic and chemical properties of the RIS are consistent with a semiquinone-type radical underlying the RIS. It has been suggested that semiquinone radicals formed on trace amounts of melanin in nails are the basis for the RIS signals. However, based on the quantum chemical calculations and chemical properties of the RIS, it is likely that the radicals underlying this signal are generated from the radiolysis of L-3,4-dihydroxyphenylalanine (DOPA) amino acids in the keratin proteins. These DOPA amino acids are likely formed from the exogenous oxidation of tyrosine in keratin by the oxygen from the air prior to irradiation. We show that these DOPA amino acids can work as radical traps, capturing the highly reactive and unstable

  19. 3-Dimensional atomic scale structure of the ionic liquid-graphite interface elucidated by AM-AFM and quantum chemical simulations

    Science.gov (United States)

    Page, Alister J.; Elbourne, Aaron; Stefanovic, Ryan; Addicoat, Matthew A.; Warr, Gregory G.; Voïtchovsky, Kislon; Atkin, Rob

    2014-06-01

    In situ amplitude modulated atomic force microscopy (AM-AFM) and quantum chemical simulations are used to resolve the structure of the highly ordered pyrolytic graphite (HOPG)-bulk propylammonium nitrate (PAN) interface with resolution comparable with that achieved for frozen ionic liquid (IL) monolayers using STM. This is the first time that (a) molecular resolution images of bulk IL-solid interfaces have been achieved, (b) the lateral structure of the IL graphite interface has been imaged for any IL, (c) AM-AFM has elucidated molecular level structure immersed in a viscous liquid and (d) it has been demonstrated that the IL structure at solid surfaces is a consequence of both thermodynamic and kinetic effects. The lateral structure of the PAN-graphite interface is highly ordered and consists of remarkably well-defined domains of a rhomboidal superstructure composed of propylammonium cations preferentially aligned along two of the three directions in the underlying graphite lattice. The nanostructure is primarily determined by the cation. Van der Waals interactions between the propylammonium chains and the surface mean that the cation is enriched in the surface layer, and is much less mobile than the anion. The presence of a heterogeneous lateral structure at an ionic liquid-solid interface has wide ranging ramifications for ionic liquid applications, including lubrication, capacitive charge storage and electrodeposition.In situ amplitude modulated atomic force microscopy (AM-AFM) and quantum chemical simulations are used to resolve the structure of the highly ordered pyrolytic graphite (HOPG)-bulk propylammonium nitrate (PAN) interface with resolution comparable with that achieved for frozen ionic liquid (IL) monolayers using STM. This is the first time that (a) molecular resolution images of bulk IL-solid interfaces have been achieved, (b) the lateral structure of the IL graphite interface has been imaged for any IL, (c) AM-AFM has elucidated molecular level

  20. Photoinduced intramolecular charge transfer (ICT) reaction in trans-methyl p-(dimethylamino) cinnamate: A combined fluorescence measurement and quantum chemical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Amrita [Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009 (India); Kar, Samiran [Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Guchhait, Nikhil [Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009 (India)], E-mail: nikhilg@postmark.net

    2006-01-05

    The photophysical behaviour of trans-methyl p-(dimethylamino) cinnamate (t-MDMAC) donor-acceptor system has been investigated by steady-state absorption and emission spectroscopy and quantum chemical calculations. The molecule t-MDMAC shows an emission from the locally excited state in non-polar solvents. In addition to weak local emission, a strong solvent dependent red shifted fluorescence in polar aprotic solvents is attributed to highly polar intramolecular charge transfer state. However, the formation of hydrogen-bonded clusters with polar protic solvents has been suggested from a linear correlation between the observed red shifted fluorescence band maxima with hydrogen bonding parameters ({alpha}). Calculations by ab initio and density functional theory show that the lone pair electron at nitrogen center is out of plane of the benzene ring in the global minimum ground state structure. In the gas phase, a potential energy surface along the twist coordinate at the donor (-NMe{sub 2}) and acceptor (-CH = CHCOOMe) sites shows stabilization of S{sub 1} state and destabilization S{sub 2} and S{sub 0} states. A similar potential energy calculation along the twist coordinate in acetonitrile solvent using non-equilibrium polarized continuum model also shows more stabilization of S{sub 1} state relative to other states and supports solvent dependent red shifted emission properties. In all types of calculations it is found that the nitrogen lone pair is delocalized over the benzene ring in the global minimum ground state and is localized on the nitrogen centre at the 90 deg. twisted configuration. The S{sub 1} energy state stabilization along the twist coordinate at the donor site and localized nitrogen lone pair at the perpendicular configuration support well the observed dual fluorescence in terms of proposed twisted intramolecular charge transfer (TICT) model.

  1. Chlorination pattern effect on thermodynamic parameters and environmental degradability for C₁₀-SCCPs: Quantum chemical calculation based on virtual combinational library.

    Science.gov (United States)

    Sun, Yuzhen; Pan, Wenxiao; Lin, Yuan; Fu, Jianjie; Zhang, Aiqian

    2016-01-01

    Short-chain chlorinated paraffins (SCCPs) are still controversial candidates for inclusion in the Stockholm Convention. The inherent mixture nature of SCCPs makes it rather difficult to explore their environmental behaviors. A virtual molecule library of 42,720 C10-SCCP congeners covering the full structure spectrum was constructed. We explored the structural effects on the thermodynamic parameters and environmental degradability of C10-SCCPs through semi-empirical quantum chemical calculations. The thermodynamic properties were acquired using the AM1 method, and frontier molecular orbital analysis was carried out to obtain the E(HOMO), E(LUMO) and E(LUMO)-E(HOMO) for degradability exploration at the same level. The influence of the chlorination degree (N(Cl)) on the relative stability and environmental degradation was elucidated. A novel structural descriptor, μ, was proposed to measure the dispersion of the chlorine atoms within a molecule. There were significant correlations between thermodynamic values and N(Cl), while the reported N(Cl)-dependent pollution profile of C10-SCCPs in environmental samples was basically consistent with the predicted order of formation stability of C10-SCCP congeners. In addition, isomers with large μ showed higher relative stability than those with small μ. This could be further verified by the relationship between μ and the reactivity of nucleophilic substitution and OH attack respectively. The C10-SCCP congeners with less Cl substitution and lower dispersion degree are susceptible to environmental degradation via nucleophilic substitution and hydroxyl radical attack, while direct photolysis of C10-SCCP congeners cannot readily occur due to the large E(LUMO)-E(HOMO) values. The chlorination effect and the conclusions were further checked with appropriate density functional theory (DFT) calculations. Copyright © 2015. Published by Elsevier B.V.

  2. Exploring the dynamics of reaction N((2)D)+C2H4 with crossed molecular-beam experiments and quantum-chemical calculations.

    Science.gov (United States)

    Lee, Shih-Huang; Chin, Chih-Hao; Chen, Wei-Kan; Huang, Wen-Jian; Hsieh, Chu-Chun

    2011-05-14

    We conducted the title reaction using a crossed molecular-beam apparatus, quantum-chemical calculations, and RRKM calculations. Synchrotron radiation from an undulator served to ionize selectively reaction products by advantage of negligibly small dissociative ionization. We observed two products with gross formula C(2)H(3)N and C(2)H(2)N associated with loss of one and two hydrogen atoms, respectively. Measurements of kinetic-energy distributions, angular distributions, low-resolution photoionization spectra, and branching ratios of the two products were carried out. Furthermore, we evaluated total branching ratios of various exit channels using RRKM calculations based on the potential-energy surface of reaction N((2)D)+C(2)H(4) established with the method CCSD(T)/6-311+G(3df,2p)//B3LYP/6-311G(d,p)+ZPE[B3LYP/6-311G(d,p)]. The combination of experimental and computational results allows us to reveal the reaction dynamics. The N((2)D) atom adds to the C=C π-bond of ethene (C(2)H(4)) to form a cyclic complex c-CH(2)(N)CH(2) that directly ejects a hydrogen atom or rearranges to other intermediates followed by elimination of a hydrogen atom to produce C(2)H(3)N; c-CH(2)(N)CH+H is the dominant product channel. Subsequently, most C(2)H(3)N radicals, notably c-CH(2)(N)CH, further decompose to CH(2)CN+H. This work provides results and explanations different from the previous work of Balucani et al. [J. Phys. Chem. A, 2000, 104, 5655], indicating that selective photoionization with synchrotron radiation as an ionization source is a good choice in chemical dynamics research.

  3. Molecular structure, electronic properties, NLO, NBO analysis and spectroscopic characterization of Gabapentin with experimental (FT-IR and FT-Raman) techniques and quantum chemical calculations

    Science.gov (United States)

    Sinha, Leena; Karabacak, Mehmet; Narayan, V.; Cinar, Mehmet; Prasad, Onkar

    2013-05-01

    Gabapentin (GP), structurally related to the neurotransmitter GABA (gamma-aminobutyric acid), mimics the activity of GABA and is also widely used in neurology for the treatment of peripheral neuropathic pain. It exists in zwitterionic form in solid state. The present communication deals with the quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of GP using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. In view of the fact that amino acids exist as zwitterions as well as in the neutral form depending on the environment (solvent, pH, etc.), molecular properties of both the zwitterionic and neutral form of GP have been analyzed. The fundamental vibrational wavenumbers as well as their intensities were calculated and compared with experimental FT-IR and FT-Raman spectra. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The electric dipole moment, polarizability and the first hyperpolarizability values of the GP have been calculated at the same level of theory and basis set. The nonlinear optical (NLO) behavior of zwitterionic and neutral form has been compared. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet-visible (UV-Vis) spectrum of the title molecule has also been calculated using TD-DFT method. The thermodynamic properties of both the zwitterionic and neutral form of GP at different temperatures have been calculated.

  4. Cob(I)alamin: insight into the nature of electronically excited states elucidated via quantum chemical computations and analysis of absorption, CD and MCD data.

    Science.gov (United States)

    Kornobis, Karina; Ruud, Kenneth; Kozlowski, Pawel M

    2013-02-07

    The nature of electronically excited states of the super-reduced form of vitamin B(12) (i.e., cob(I)alamin or B(12s)), a ubiquitous B(12) intermediate, was investigated by performing quantum-chemical calculations within the time-dependent density functional theory (TD-DFT) framework and by establishing their correspondence to experimental data. Using response theory, the electronic absorption (Abs), circular dichroism (CD) and magnetic CD (MCD) spectra of cob(I)alamin were simulated and directly compared with experiment. Several issues have been taken into considerations while performing the TD-DFT calculations, such as strong dependence on the applied exchange-correlation (XC) functional or structural simplification imposed on the cob(I)alamin. In addition, the low-lying transitions were also validated by performing CASSCF/MC-XQDPT2 calculations. By comparing computational results with existing experimental data a new level of understanding of electronic excitations has been established at the molecular level. The present study extends and confirms conclusions reached for other cobalamins. In particular, the better performance of the BP86 functional, rather than hybrid-type, was observed in terms of the excitations associated with both Co d and corrin π localized transitions. In addition, the lowest energy band was associated with multiple metal-to-ligand charge transfer excitations as opposed to the commonly assumed view of a single π → π* transition followed by vibrational progression. Finally, the use of the full cob(I)alamin structure, instead of simplified molecular models, shed new light on the spectral analyses of cobalamin systems and revealed new challenges of this approach related to long-range charge transfer excitations involving side chains.

  5. Synthesis, Characterization, Antimicrobial Studies and Corrosion Inhibition Potential of 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane: Experimental and Quantum Chemical Studies

    Directory of Open Access Journals (Sweden)

    Henry U. Nwankwo

    2016-02-01

    Full Text Available The macrocylic ligand, 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane (MHACD was synthesized by the demetallation of its freshly synthesized Ni(II complex (NiMHACD. Successful synthesis of NiMHACD and the free ligand (MHACD was confirmed by various characterization techniques, including Fourier transform infra-red (FT-IR, proton nuclear magnetic resonance (1H-NMR, carbon-13 nuclear magnetic resonance (13C-NMR, ultraviolet-visible (UV-vis, and energy dispersive x-ray (EDX spectroscopic techniques. The anti-bacteria activities of MHACD were investigated against Staphylococcus aureus and Enterococcus species and the results showed that MHACD possesses a spectrum of activity against the two bacteria. The electrochemical cyclic voltammetry study on MHACD revealed that it is a redox active compound with promising catalytic properties in electrochemical applications. The inhibition potential of MHACD for mild steel corrosion in 1 M HCl was investigated using potentiodynamic polarization method. The results showed that MHACD inhibits steel corrosion as a mixed-type inhibitor, and the inhibition efficiency increases with increasing concentration of MHACD. The adsorption of MHACD obeys the Langmuir adsorption isotherm; it is spontaneous and involves competitive physisorption and chemisorption mechanisms. Quantum chemical calculations revealed that the energy of the highest occupied molecular orbital (HOMO of MHACD is high enough to favor forward donation of charges to the metal during adsorption and corrosion inhibition. Natural bond orbital (NBO analysis revealed the presence of various orbitals in the MHACD that are capable of donating or accepting electrons under favorable conditions.

  6. Complexation reactions in pyridine and 2,6-dimethylpyridine-water system: The quantum-chemical description and the path to liquid phase separation

    Science.gov (United States)

    Chernia, Zelig; Tsori, Yoav

    2018-03-01

    Phase separation in substituted pyridines in water is usually described as an interplay between temperature-driven breakage of hydrogen bonds and the associating interaction of the van der Waals force. In previous quantum-chemical studies, the strength of hydrogen bonding between one water and one pyridine molecules (the 1:1 complex) was assigned a pivotal role. It was accepted that the disassembly of the 1:1 complex at a critical temperature leads to phase separation and formation of the miscibility gap. Yet, for over two decades, notable empirical data and theoretical arguments were presented against that view, thus revealing the need in a revised quantum-mechanical description. In the present study, pyridine-water and 2,6-dimethylpyridine-water systems at different complexation stages are calculated using high level Kohn-Sham theory. The hydrophobic-hydrophilic properties are accounted for by the polarizable continuum solvation model. Inclusion of solvation in free energy of formation calculations reveals that 1:1 complexes are abundant in the organically rich solvents but higher level oligomers (i.e., 2:1 dimers with two pyridines and one water molecule) are the only feasible stable products in the more polar media. At the critical temperature, the dissolution of the external hydrogen bonds between the 2:1 dimer and the surrounding water molecules induces the demixing process. The 1:1 complex acts as a precursor in the formation of the dimers but is not directly involved in the demixing mechanism. The existence of the miscibility gap in one pyridine-water system and the lack of it in another is explained by the ability of the former to maintain stable dimerization. Free energy of formation of several reaction paths producing the 2:1 dimers is calculated and critically analyzed.

  7. Rotational spectra of rare isotopic species of fluoroiodomethane: determination of the equilibrium structure from rotational spectroscopy and quantum-chemical calculations.

    Science.gov (United States)

    Puzzarini, Cristina; Cazzoli, Gabriele; López, Juan Carlos; Alonso, José Luis; Baldacci, Agostino; Baldan, Alessandro; Stopkowicz, Stella; Cheng, Lan; Gauss, Jürgen

    2012-07-14

    Supported by accurate quantum-chemical calculations, the rotational spectra of the mono- and bi-deuterated species of fluoroiodomethane, CHDFI and CD(2)FI, as well as of the (13)C-containing species, (13)CH(2)FI, were recorded for the first time. Three different spectrometers were employed, a Fourier-transform microwave spectrometer, a millimeter/submillimter-wave spectrometer, and a THz spectrometer, thus allowing to record a huge portion of the rotational spectrum, from 5 GHz up to 1.05 THz, and to accurately determine the ground-state rotational and centrifugal-distortion constants. Sub-Doppler measurements allowed to resolve the hyperfine structure of the rotational spectrum and to determine the complete iodine quadrupole-coupling tensor as well as the diagonal elements of the iodine spin-rotation tensor. The present investigation of rare isotopic species of CH(2)FI together with the results previously obtained for the main isotopologue [C. Puzzarini, G. Cazzoli, J. C. López, J. L. Alonso, A. Baldacci, A. Baldan, S. Stopkowicz, L. Cheng, and J. Gauss, J. Chem. Phys. 134, 174312 (2011); G. Cazzoli, A. Baldacci, A. Baldan, and C. Puzzarini, Mol. Phys. 109, 2245 (2011)] enabled us to derive a semi-experimental equilibrium structure for fluoroiodomethane by means of a least-squares fit procedure using the available experimental ground-state rotational constants together with computed vibrational corrections. Problems related to the missing isotopic substitution of fluorine and iodine were overcome thanks to the availability of an accurate theoretical equilibrium geometry (computed at the coupled-cluster singles and doubles level augmented by a perturbative treatment of triple excitations).

  8. Incidence of Extraprostatic Extension at Radical Prostatectomy with Pure Gleason Score 3 + 3 = 6 (Grade Group 1) Cancer: Implications for Whether Gleason Score 6 Prostate Cancer Should be Renamed "Not Cancer" and for Selection Criteria for Active Surveillance.

    Science.gov (United States)

    Hassan, Oudai; Han, Misop; Zhou, Amy; Paulk, Adina; Sun, Yue; Al-Harbi, Abdullah; Alrajjal, Ahmed; Baptista Dos Santos, Filipa; Epstein, Jonathan I

    2018-06-01

    We assessed the risk of locally aggressive behavior in pure Gleason score 6 (Grade Group 1) prostate cancer using contemporary grading criteria. To our knowledge this has been studied in only 1 prior cohort. We evaluated consecutive radical prostatectomy specimens from an academic institution, including those from 3,291 men with Gleason score 6 and 4,202 with Gleason score 3 + 4 = 7 (Grade Group 2) disease between 2005 and 2016. For dichotomous variables the Pearson chi-square test was used. Of the 3,288 Gleason score 6 cancer cases 128 (3.9%) showed focal extraprostatic extension compared to 593 of the 4,202 (14.1%) with Gleason score 3 + 4 = 7 (p <0.0001). Of the 3,288 Gleason score 6 cancer cases 79 (2.4%) showed nonfocal extraprostatic extension compared to 639 of the 4,202 (15.2%) with Gleason score 3 + 4 = 7 (p <0.0001). The incidence of focal extraprostatic extension with Gleason score 3 + 4 = 7 with less than 5% Gleason pattern 4 was 129 of 1,147 cases (11.2%), which was between Gleason scores 6 and 3 + 4 = 7 with greater than 5% Gleason pattern 4. The incidence of nonfocal extraprostatic extension in Gleason score 3 + 4 = 7 with less than 5% Gleason pattern 4 was 96 of 1,147 cases (8.4%), which was between Gleason scores 6 and 3 + 4 = 7 with greater than 5% Gleason pattern 4. One of the 3,290 Gleason score 6 cases (0.03%) showed seminal vesicle invasion compared to 93 of the 4,202 (2.2%) of Gleason score 3 + 4 = 7 (p <0.0001). A limitation of our study was its retrospective design. It is not rare for pure Gleason score 6 prostate cancer to locally extend out of the prostate 3.9% focally and 2.4% nonfocally. In extremely rare cases Gleason score 6 can be associated with seminal vesicle invasion and yet not lymph node metastases. Our overall findings support the argument for continuing to use the term cancer for these tumors. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  9. Quotient semigroups and extension semigroups

    Indian Academy of Sciences (India)

    Introduction. Abelian groups and semigroups play an important role in the classification of C. ∗. -algebras and their extensions. ... -algebra extension theory and K K-theory, it is crucial to study the theory of quotient semigroups from the ...

  10. Multi-scale multi-physics computational chemistry simulation based on ultra-accelerated quantum chemical molecular dynamics method for structural materials in boiling water reactor

    International Nuclear Information System (INIS)

    Miyamoto, Akira; Sato, Etsuko; Sato, Ryo; Inaba, Kenji; Hatakeyama, Nozomu

    2014-01-01

    In collaboration with experimental experts we have reported in the present conference (Hatakeyama, N. et al., “Experiment-integrated multi-scale, multi-physics computational chemistry simulation applied to corrosion behaviour of BWR structural materials”) the results of multi-scale multi-physics computational chemistry simulations applied to the corrosion behaviour of BWR structural materials. In macro-scale, a macroscopic simulator of anode polarization curve was developed to solve the spatially one-dimensional electrochemical equations on the material surface in continuum level in order to understand the corrosion behaviour of typical BWR structural material, SUS304. The experimental anode polarization behaviours of each pure metal were reproduced by fitting all the rates of electrochemical reactions and then the anode polarization curve of SUS304 was calculated by using the same parameters and found to reproduce the experimental behaviour successfully. In meso-scale, a kinetic Monte Carlo (KMC) simulator was applied to an actual-time simulation of the morphological corrosion behaviour under the influence of an applied voltage. In micro-scale, an ultra-accelerated quantum chemical molecular dynamics (UA-QCMD) code was applied to various metallic oxide surfaces of Fe 2 O 3 , Fe 3 O 4 , Cr 2 O 3 modelled as same as water molecules and dissolved metallic ions on the surfaces, then the dissolution and segregation behaviours were successfully simulated dynamically by using UA-QCMD. In this paper we describe details of the multi-scale, multi-physics computational chemistry method especially the UA-QCMD method. This method is approximately 10,000,000 times faster than conventional first-principles molecular dynamics methods based on density-functional theory (DFT), and the accuracy was also validated for various metals and metal oxides compared with DFT results. To assure multi-scale multi-physics computational chemistry simulation based on the UA-QCMD method for

  11. Quantum-chemical ab initio calculations on the three isomers of diborabenzene (C{sub 4}H{sub 4}B{sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jaswinder; Raabe, Gerhard [Inst. fuer Organische Chemie, RWTH Aachen Univ. (Germany); Wang Yuekui [Key Lab. of Chemical Biology and Molecular Engineering of the Education Ministry, Inst. of Molecular Science, Shanxi Univ., Taiyuan, SH (China)

    2010-01-15

    Quantum-chemical ab initio calculations up to the ZPE+CCSD(T)/aug-cc-pVTZ/MP2/6-311++G** level were performed on three possible structural isomers of diborabenzene (C{sub 4}H{sub 4}B{sub 2}). All three molecules were found to be local minima on the C{sub 4}H{sub 4}B{sub 2} energy surface and to have closed shell singlet ground states. While the ground states of the 1,3- and 1,4-isomer are planar and of C{sub 2v} and D{sub 2h} symmetry, respectively, 1,2-diborabenzene is non-planar with a C{sub 2} axis passing through the center of the BB bond and the middle of the opposite carbon-carbon bond as the only symmetry element. The energetically most favourable 1,3-diborabenzene was found to be about 19 and 36 kcal/mol lower in energy than the 1,2- and the 1,4-isomer. Planar 1,3- and 1,4-diborabenzene have three doubly occupied {pi} orbitals while non-planar 1,2-diborabenzene has also three doubly occupied orbitals which can be derived from the {pi} orbitals of its 3.7 kcal/mol energetically less favourable planar form (''{pi}=like'' orbitals). The lowest unoccupied orbitals of all three isomers have {sigma} symmetry with large coefficients at the two boron atoms. These orbitals are lower in energy than the lowest unoccupied molecular orbitals (LUMOs) of e. g. benzene and pyridine and might cause pronounced acceptor properties which could be one of the reasons for the elusiveness of the title compounds. The results of bond separation reactions show that cyclic conjugation stabilizes all three diborabenzenes relative to their isolated fragments. The most effective stabilization energy of about 24 kcal/mol was found for the energetically lowest 1,3-isomer. This value amounts to approximately one third of the experimental value for the bond separation energy of pyridine. In all cases the energetically lowest triplet states are significantly (16 - 24 kcal/mol) higher in energy than the singlet ground states. Also among the triplets the 1,3-isomer is the

  12. Quantum chemical analysis of thermodynamics of 2D cluster formation of alkanes at the water/vapor interface in the presence of aliphatic alcohols.

    Science.gov (United States)

    Vysotsky, Yu B; Kartashynska, E S; Belyaeva, E A; Fainerman, V B; Vollhardt, D; Miller, R

    2015-11-21

    Using the quantum chemical semi-empirical PM3 method it is shown that aliphatic alcohols favor the spontaneous clusterization of vaporous alkanes at the water surface due to the change of adsorption from the barrier to non-barrier mechanism. A theoretical model of the non-barrier mechanism for monolayer formation is developed. In the framework of this model alcohols (or any other surfactants) act as 'floats', which interact with alkane molecules of the vapor phase using their hydrophobic part, whereas the hydrophilic part is immersed into the water phase. This results in a significant increase of contact effectiveness of alkanes with the interface during the adsorption and film formation. The obtained results are in good agreement with the existing experimental data. To test the model the thermodynamic and structural parameters of formation and clusterization are calculated for vaporous alkanes C(n)H(2n+2) (n(CH3) = 6-16) at the water surface in the presence of aliphatic alcohols C(n)H(2n+1)OH (n(OH) = 8-16) at 298 K. It is shown that the values of clusterization enthalpy, entropy and Gibbs' energy per one monomer of the cluster depend on the chain lengths of corresponding alcohols and alkanes, the alcohol molar fraction in the monolayers formed, and the shift of the alkane molecules with respect to the alcohol molecules Δn. Two possible competitive structures of mixed 2D film alkane-alcohol are considered: 2D films 1 with single alcohol molecules enclosed by alkane molecules (the alcohols do not form domains) and 2D films 2 that contain alcohol domains enclosed by alkane molecules. The formation of the alkane films of the first type is nearly independent of the surfactant type present at the interface, but depends on their molar fraction in the monolayer formed and the chain length of the compounds participating in the clusterization, whereas for the formation of the films of the second type the interaction between the hydrophilic parts of the surfactant is

  13. Dimension and extensions

    CERN Document Server

    Aarts, JM

    1993-01-01

    Two types of seemingly unrelated extension problems are discussed in this book. Their common focus is a long-standing problem of Johannes de Groot, the main conjecture of which was recently resolved. As is true of many important conjectures, a wide range of mathematical investigations had developed, which have been grouped into the two extension problems. The first concerns the extending of spaces, the second concerns extending the theory of dimension by replacing the empty space with other spaces. The problem of de Groot concerned compactifications of spaces by means of an adjunction of a set of minimal dimension. This minimal dimension was called the compactness deficiency of a space. Early success in 1942 lead de Groot to invent a generalization of the dimension function, called the compactness degree of a space, with the hope that this function would internally characterize the compactness deficiency which is a topological invariant of a space that is externally defined by means of compact extensions of a...

  14. Post-hoc analysis of MCI186-17, the extension study to MCI186-16, the confirmatory double-blind, parallel-group, placebo-controlled study of edaravone in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Takahashi, Fumihiro; Takei, Koji; Tsuda, Kikumi; Palumbo, Joseph

    2017-10-01

    In the 24-week double-blind study of edaravone in ALS (MCI186-16), edaravone did not show a statistically significant difference versus placebo for the primary efficacy endpoint. For post-hoc analyses, two subpopulations were identified in which edaravone might be expected to show efficacy: the efficacy-expected subpopulation (EESP), defined by scores of ≥2 points on all 12 items of the ALS Functional Rating Scale-Revised (ALSFRS-R) and a percent predicted forced vital capacity (%FVC) ≥80% at baseline; and the definite/probable EESP 2 years (dpEESP2y) subpopulation which, in addition to EESP criteria, had definite or probable ALS diagnosed by El Escorial revised criteria, and disease duration of ≤2 years. In the 36-week extension study of MCI186-16, a 24-week double-blind comparison followed by 12 weeks of open-label edaravone (MCI186-17; NCT00424463), analyses of ALSFRS-R scores of the edaravone-edaravone group and edaravone-placebo group for the full analysis set (FAS) and EESP, as prospectively defined, were reported in a previous article. Here we additionally report results in patients who met dpEESP2y criteria at the baseline of MCI186-16. In the dpEESP2y, the difference in ALSFRS-R changes from 24 to 48 weeks between the edaravone-edaravone and edaravone-placebo groups was 2.79 (p = 0.0719), which was greater than the differences previously reported for the EESP and the FAS. The pattern of adverse events in the dpEESP2y did not show any additional safety findings to those from the earlier prospective study. In conclusion, this post-hoc analysis suggests a potential effect of edaravone between 24 and 48 weeks in patients meeting dpEESP2y criteria at baseline.

  15. Sociologists in Extension

    Science.gov (United States)

    Christenson, James A.; And Others

    1977-01-01

    The article describes the work activities of the extension sociologist, the relative advantage and disadvantage of extension roles in relation to teaching/research roles, and the relevance of sociological training and research for extension work. (NQ)

  16. No oxygen isotope exchange between water and APS-sulfate at surface temperature: Evidence from quantum chemical modeling and triple-oxygen isotope experiments

    Science.gov (United States)

    Kohl, Issaku E.; Asatryan, Rubik; Bao, Huiming

    2012-10-01

    In both laboratory experiments and natural environments where microbial dissimilatory sulfate reduction (MDSR) occurs in a closed system, the δ34S ((34S/32S)sample/(34S/32S)standard - 1) for dissolved SO42- has been found to follow a typical Rayleigh-Distillation path. In contrast, the corresponding δ18O ((18O/16O)sample/(18O/16O)standard) - 1) is seen to plateau with an apparent enrichment of between 23‰ and 29‰ relative to that of ambient water under surface conditions. This apparent steady-state in the observed difference between δ18O and δ18OO can be attributed to any of these three steps: (1) the formation of adenosine-5'-phosphosulfate (APS) from ATP and SO42-, (2) oxygen exchange between sulfite (or other downstream sulfoxy-anions) and water later in the MDSR reaction chain and its back reaction to APS and sulfate, and (3) the re-oxidation of produced H2S or precursor sulfoxy-anions to sulfate in environments containing Fe(III) or O2. This study examines the first step as a potential pathway for water oxygen incorporation into sulfate. We examined the structures and process of APS formation using B3LYP/6-31G(d,p) hybrid density functional theory, implemented in the Gaussian-03 program suite, to predict the potential for oxygen exchange. We conducted a set of in vitro, enzyme-catalyzed, APS formation experiments (with no further reduction to sulfite) to determine the degree of oxygen isotope exchange between the APS-sulfate and water. Triple-oxygen-isotope labeled water was used in the reactor solutions to monitor oxygen isotope exchange between water and APS sulfate. The formation and hydrolysis of APS were identified as potential steps for oxygen exchange with water to occur. Quantum chemical modeling indicates that the combination of sulfate with ATP has effects on bond strength and symmetry of the sulfate. However, these small effects impart little influence on the integrity of the SO42- tetrahedron due to the high activation energy required for

  17. Rational design and characterization of high-efficiency planar A–π–D–π–A type electron donors in small molecule organic solar cells: A quantum chemical approach

    International Nuclear Information System (INIS)

    Wang, Dongmei; Ding, Weilu; Geng, Zhiyuan; Wang, Li; Geng, Yun; Su, Zhongmin; Yu, Hailing

    2014-01-01

    Taking the reported donor DR3TBDT as reference, a series of A–π–D–π–A type donor molecules involving different planar donor cores were designed and investigated by using density functional theory (DFT)/time-dependent DFT methods. Preliminary calculations on geometries, energy levels and spectrum properties show that four of the designed molecules (4, 5, 12 and 13) could become potential donor replacements of DR3TBDT due to their good planarity, larger light harvesting efficiencies and similar exciton migration capability. Additionally, several factors influencing on short-circuit current density (J sc ) were analyzed by in-depth quantum chemical investigations on the transition density matrix, charge transfer indexes, exciton binding energy and Gibbs free energy loss in charge dissociation process. Comparative analyses demonstrate that 4 with indaceno[1,2-b:5,6-b′]dithiophene donor core has more significant electron transfer character and favorable exciton dissociation capability for enhancing the J sc , and would be potentially promising donor material in organic solar cells. - Graphical abstract: Display Omitted - Highlights: • A series of A–π–D–π–A type donors with different donor core for OSC were designed. • The relationship between donor properties and device performance is explored by DFT. • An In-depth quantum chemical investigation on the affecting factors on J sc . • The efficiency of new donor 4 may surpass the reported donor DR3TBDT

  18. Geometrical criteria versus quantum chemical criteria for assessment of intramolecular hydrogen bond (IMHB) interaction: A computational comparison into the effect of chlorine substitution on IMHB of salicylic acid in its lowest energy ground state conformer

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Bijan Kumar [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India); Guchhait, Nikhil, E-mail: nikhil.guchhait@rediffmail.com [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India)

    2013-02-01

    Highlights: ► Intramolecular hydrogen bonding (IMHB) in salicylic acid and its chloro derivatives. ► A complex effect of +R and −I effect of chlorine substituents on IMHB energy. ► Interplay between IMHB energy and aromaticity. ► Directional nature of IMHB from quantum chemical assessment. ► Quantum chemical treatment vs. geometrical criteria to assess weak interaction. - Abstract: Density functional theory based computational study has been performed to characterize intramolecular hydrogen bonding (IMHB) interaction in a series of salicylic acid derivatives varying in chlorine substitution on the benzene ring. The molecular systems studied are salicylic acid, 5-chlorosalicylic acid, 3,5-dichlorosalicylic acid and 3,5,6-tricholorosalicylic acid. Major emphasis is rendered on the analysis of IMHB interaction by calculation of electron density ρ(r) and Laplacian ∇{sup 2}ρ(r) at the bond critical point using atoms-in-molecule theory. Topological features, energy densities based on ρ(r) through perturbing the intramolecular H-bond distances suggest that at equilibrium geometry the IMHB interaction develops certain characteristics typical of covalent interaction. The interplay between aromaticity and resonance-assisted hydrogen bonding (RAHB) is discussed using both geometrical and magnetic criteria as the descriptors of aromaticity. The optimized geometry features, molecular electrostatic potential map analysis are also found to produce a consensus view in relation with the formation of RAHB in these systems.

  19. Molecular dynamics and quantum chemical calculation studies on 4,4-dimethyl-3-thiosemicarbazide as corrosion inhibitor in 2.5 M H{sub 2}SO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Musa, Ahmed Y., E-mail: ahmed.musa@ymail.com [Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor (Malaysia); Kadhum, Abdul Amir H.; Mohamad, Abu Bakar; Takriff, Mohd Sobri [Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor (Malaysia)

    2011-09-15

    Highlights: {yields} This work deals with a study of chemical additives for corrosion inhibition of mild steel in acidic conditions. {yields} The effects of the additive 4,4-dimethyl-3-thiosemicarbazide (DTS) on mild steel were studied by means of electrochemical techniques. {yields} Quantum chemical calculations and molecular dynamic model were performed to characterize the inhibition mechanism. {yields} The calculations provided information that helps in the analysis/interpretation of the experimental work. - Abstract: The inhibition of mild steel corrosion in a 2.5 M H{sub 2}SO{sub 4} solution by 4,4-dimethyl-3-thiosemicarbazide (DTS) was studied at 30 deg. C using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Quantum chemical parameters were calculated for DTS using PM3-SCF method. The molecular dynamic method was performed to simulate the adsorption of the DTS molecules on Fe surface. Results showed that DTS performed excellent as inhibitor for mild steel corrosion in a 2.5 M H{sub 2}SO{sub 4} solution and indicated that the inhibition efficiencies increase with the concentration of inhibitor. Theoretical results indicated that DTS could adsorb on the mild steel surface firmly through heteroatoms.

  20. Geometrical criteria versus quantum chemical criteria for assessment of intramolecular hydrogen bond (IMHB) interaction: A computational comparison into the effect of chlorine substitution on IMHB of salicylic acid in its lowest energy ground state conformer

    International Nuclear Information System (INIS)

    Paul, Bijan Kumar; Guchhait, Nikhil

    2013-01-01

    Highlights: ► Intramolecular hydrogen bonding (IMHB) in salicylic acid and its chloro derivatives. ► A complex effect of +R and −I effect of chlorine substituents on IMHB energy. ► Interplay between IMHB energy and aromaticity. ► Directional nature of IMHB from quantum chemical assessment. ► Quantum chemical treatment vs. geometrical criteria to assess weak interaction. - Abstract: Density functional theory based computational study has been performed to characterize intramolecular hydrogen bonding (IMHB) interaction in a series of salicylic acid derivatives varying in chlorine substitution on the benzene ring. The molecular systems studied are salicylic acid, 5-chlorosalicylic acid, 3,5-dichlorosalicylic acid and 3,5,6-tricholorosalicylic acid. Major emphasis is rendered on the analysis of IMHB interaction by calculation of electron density ρ(r) and Laplacian ∇ 2 ρ(r) at the bond critical point using atoms-in-molecule theory. Topological features, energy densities based on ρ(r) through perturbing the intramolecular H-bond distances suggest that at equilibrium geometry the IMHB interaction develops certain characteristics typical of covalent interaction. The interplay between aromaticity and resonance-assisted hydrogen bonding (RAHB) is discussed using both geometrical and magnetic criteria as the descriptors of aromaticity. The optimized geometry features, molecular electrostatic potential map analysis are also found to produce a consensus view in relation with the formation of RAHB in these systems

  1. Adsorption and Corrosion Inhibition Studies of Some Selected Dyes as Corrosion Inhibitors for Mild Steel in Acidic Medium: Gravimetric, Electrochemical, Quantum Chemical Studies and Synergistic Effect with Iodide Ions

    Directory of Open Access Journals (Sweden)

    Thabo Peme

    2015-09-01

    Full Text Available The corrosion inhibition properties of some organic dyes, namely Sunset Yellow (SS, Amaranth (AM, Allura Red (AR, Tartrazine (TZ and Fast Green (FG, for mild steel corrosion in 0.5 M HCl solution, were investigated using gravimetric, potentiodynamic polarization techniques and quantum chemical calculations. The results showed that the studied dyes are good corrosion inhibitors with enhanced inhibition efficiencies. The inhibition efficiency of all the studied dyes increases with increase in concentration, and decreases with increase in temperature. The results showed that the inhibition efficiency of the dyes increases in the presence of KI due to synergistic interactions of the dye molecules with iodide (I− ions. Potentiodynamic polarization results revealed that the studied dyes are mixed-type inhibitors both in the absence and presence of KI. The adsorption of the studied dyes on mild steel surface, with and without KI, obeys the Langmuir adsorption isotherm and involves physical adsorption mechanism. Quantum chemical calculations revealed that the most likely sites in the dye molecules for interactions with mild steel are the S, O, and N heteroatoms.

  2. Adsorption and Corrosion Inhibition Studies of Some Selected Dyes as Corrosion Inhibitors for Mild Steel in Acidic Medium: Gravimetric, Electrochemical, Quantum Chemical Studies and Synergistic Effect with Iodide Ions.

    Science.gov (United States)

    Peme, Thabo; Olasunkanmi, Lukman O; Bahadur, Indra; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-09-02

    The corrosion inhibition properties of some organic dyes, namely Sunset Yellow (SS), Amaranth (AM), Allura Red (AR), Tartrazine (TZ) and Fast Green (FG), for mild steel corrosion in 0.5 M HCl solution, were investigated using gravimetric, potentiodynamic polarization techniques and quantum chemical calculations. The results showed that the studied dyes are good corrosion inhibitors with enhanced inhibition efficiencies. The inhibition efficiency of all the studied dyes increases with increase in concentration, and decreases with increase in temperature. The results showed that the inhibition efficiency of the dyes increases in the presence of KI due to synergistic interactions of the dye molecules with iodide (I(-)) ions. Potentiodynamic polarization results revealed that the studied dyes are mixed-type inhibitors both in the absence and presence of KI. The adsorption of the studied dyes on mild steel surface, with and without KI, obeys the Langmuir adsorption isotherm and involves physical adsorption mechanism. Quantum chemical calculations revealed that the most likely sites in the dye molecules for interactions with mild steel are the S, O, and N heteroatoms.

  3. Group Work

    Science.gov (United States)

    Wilson, Kristy J.; Brickman, Peggy; Brame, Cynthia J.

    2018-01-01

    Science, technology, engineering, and mathematics faculty are increasingly incorporating both formal and informal group work in their courses. Implementing group work can be improved by an understanding of the extensive body of educational research studies on this topic. This essay describes an online, evidence-based teaching guide published by…

  4. Can hydroxylamine be a more potent nucleophile for the reactivation of tabun-inhibited AChE than prototype oxime drugs? An answer derived from quantum chemical and steered molecular dynamics studies.

    Science.gov (United States)

    Lo, Rabindranath; Ganguly, Bishwajit

    2014-07-29

    Organophosphorus nerve agents are highly toxic compounds which strongly inhibit acetylcholinesterase (AChE) in the blood and in the central nervous system (CNS). Tabun is one of the highly toxic organophosphorus (OP) compounds and is resistant to many oxime drugs formulated for the reactivation of AChE. The reactivation mechanism of tabun-conjugated AChE with various drugs has been examined with density functional theory and ab initio quantum chemical calculations. The presence of a lone-pair located on the amidic group resists the nucleophilic attack at the phosphorus center of the tabun-conjugated AChE. We have shown that the newly designed drug candidate N-(pyridin-2-yl)hydroxylamine, at the MP2/6-31+G*//M05-2X/6-31G* level in the aqueous phase with the polarizable continuum solvation model (PCM), is more effective in reactivating the tabun-conjugated AChE than typical oxime drugs. The rate determining activation barrier with N-(pyridin-2-yl)hydroxylamine was found to be ∼1.7 kcal mol(-1), which is 7.2 kcal mol(-1) lower than the charged oxime trimedoxime (one of the most efficient reactivators in tabun poisonings). The greater nucleophilicity index (ω(-)) and higher CHelpG charge of pyridinylhydroxylamine compared to TMB4 support this observation. Furthermore, we have also examined the reactivation process of tabun-inhibited AChE with some other bis-quaternary oxime drug candidates such as methoxime (MMB4) and obidoxime. The docking analysis suggests that charged bis-quaternary pyridinium oximes have greater binding affinity inside the active-site gorge of AChE compared to the neutral pyridinylhydroxylamine. The peripheral ligand attached to the neutral pyridinylhydroxylamine enhanced the binding with the aromatic residues in the active-site gorge of AChE through effective π-π interactions. Steered molecular dynamics (SMD) simulations have also been performed with the charged oxime (TMB4) and the neutral hydroxylamine. From protein-drug interaction

  5. Potential energy profile, structural, vibrational and reactivity descriptors of trans-2-methoxycinnamic acid by FTIR, FT-Raman and quantum chemical studies

    Science.gov (United States)

    Arjunan, V.; Anitha, R.; Thenmozhi, S.; Marchewka, M. K.; Mohan, S.

    2016-06-01

    The stable conformers of trans-2-methoxycinnamic acid (trans-2MCA) are determined by potential energy profile analysis. The energies of the s-cis and s-trans conformers of trans-2MCA determined by B3LYP/cc-pVTZ method are -612.9788331 Hartrees and -612.9780953 Hartrees, respectively. The vibrational and electronic investigations of the stable s-cis and s-trans conformers of trans-2-methoxycinnamic acid have been carried out extensively with FTIR and FT-Raman spectral techniques. The s-cis conformer (I) with a (C16-C17-C18-O19) dihedral angle equal to 0° is found to be more favoured relative to the one s-trans (II) with (C16-C17-C18-O19) = 180°, possibly due to delocalization, hydrogen bonding and steric repulsion effects between the methoxy and acrylic acid groups. The DFT studies are performed with B3LYP method by utilizing 6-311++G** and cc-pVTZ basis sets to determine the structure, thermodynamic properties, vibrational characteristics and chemical shifts of the compound. The total dipole moments of the conformers determined by B3LYP/cc-pVTZ method are 3.35 D and 4.87 D for s-cis and s-trans, respectively. It reveals the higher polarity of s-trans conformer of trans-2MCA molecule. The electronic and steric influence of the methoxy group on the skeletal frequencies has been analysed. The energies of the frontier molecular orbitals and the LUMO-HOMO energy gap have been determined. The MEP of s-cis conformer lie in the range +1.374e × 10-2 to -1.374e × 10-2 while for s-trans it is +1.591e × 10-2 to -1.591e × 10-2. The total electron density of s-cis conformer lie in the range +5.273e × 10-2 to -5.273e × 10-2 while for s-trans it is +5.403e × 10-2 to -5.403e × 10-2. The MEP and total electron density shows that the s-cis conformer is less polar, less reactive and more stable than the s-trans conformer. All the reactivity descriptors of the molecule have been discussed. Intramolecular electronic interactions and their stabilisation energies have analysed

  6. Permutation groups

    CERN Document Server

    Passman, Donald S

    2012-01-01

    This volume by a prominent authority on permutation groups consists of lecture notes that provide a self-contained account of distinct classification theorems. A ready source of frequently quoted but usually inaccessible theorems, it is ideally suited for professional group theorists as well as students with a solid background in modern algebra.The three-part treatment begins with an introductory chapter and advances to an economical development of the tools of basic group theory, including group extensions, transfer theorems, and group representations and characters. The final chapter feature

  7. Influence of more extensive radiotherapy and adjuvant chemotherapy on long-term outcome of early-stage Hodgkin's disease: a meta-analysis of 23 randomized trials involving 3,888 patients. International Hodgkin's Disease Collaborative Group

    DEFF Research Database (Denmark)

    Specht, L.; Gray, R.G.; Clarke, M.J.

    1998-01-01

    PURPOSE: To assess the effect of more extensive radiotherapy and of adjuvant combination chemotherapy on long-term outcome of early-stage Hodgkin's disease. METHODS: In a collaborative worldwide systematic overview, individual patient data were centrally reviewed on 1,974 patients in eight.......7%; P counterbalanced by a nonsignificant excess of deaths from other...... causes (12.4% v 10.0% 10-year risk). CONCLUSION: More extensive radiotherapy fields or the addition of chemotherapy to radiotherapy in the initial treatment of early-stage Hodgkin's disease had a large effect on disease control, but only a small effect on overall survival. Recurrences could be prevented...

  8. Practical routes to (SiH₃)₃P: applications in group IV semiconductor activation and in group III-V molecular synthesis.

    Science.gov (United States)

    Tice, Jesse B; Chizmeshya, A V G; Tolle, J; D' Costa, V R; Menendez, J; Kouvetakis, J

    2010-05-21

    The (SiH₃)₃P hydride is introduced as a practical source for n-doping of group IV semiconductors and as a highly-reactive delivery agent of -(SiH₃)₂P functionalities in exploratory synthesis. In contrast to earlier methods, the compound is produced here in high purity quantitative yields via a new single-step method based on reactions of SiH₃Br and (Me₃Sn)₃P, circumventing the need for toxic and unstable starting materials. As an initial demonstration of its utility we synthesized monosubstituted Me₂M-P(SiH₃)₂ (M = Al, Ga, In) derivatives of Me₃M containing the (SiH₃)₂P ligand for the first time, in analogy to the known Me₂M-P(SiMe₃)₂ counterparts. A dimeric structure of Me₂M-P(SiH₃)₂ is proposed on the basis of spectroscopic characterizations and quantum chemical simulations. Next, in the context of materials synthesis, the (SiH₃)₃P compound was used to dope germanium for the first time by building a prototype p(++)Si(100)/i-Ge/n-Ge photodiode structure. The resultant n-type Ge layers contained active carrier concentrations of 3-4 × 10¹⁹ atoms cm⁻³ as determined by spectroscopic ellipsometry and confirmed by SIMS. Strain analysis using high resolution XRD yielded a Si content of 4 × 10²⁰ atoms cm⁻³ in agreement with SIMS and within the range expected for incorporating Si₃P type units into the diamond cubic Ge matrix. Extensive characterizations for structure, morphology and crystallinity indicate that the Si co-dopant plays essentially a passive role and does not compromise the device quality of the host material nor does it fundamentally alter its optical properties.

  9. Journal of Agricultural Extension

    African Journals Online (AJOL)

    Scope of journal The Journal of Agricultural Extension" is devoted to the advancement of knowledge of agricultural extension services and practice through the publication of original and empirically based research, ... Vol 22, No 1 (2018) ... Symbol recognition and interpretation of HIV/AIDS pictorial messages among rural ...

  10. Priorities for Extension.

    Science.gov (United States)

    Hayward, J. A.

    Agricultural extension is one component in an array including research, training, education, marketing, international trade, etc. which develop together to bring about growth, and sustained growth determines the priorities for extension. These priorities depend inevitably on the stage of development of a country or region, and on the current…

  11. Nuclear plant life extension

    International Nuclear Information System (INIS)

    Negin, C.A.

    1989-01-01

    The nuclear power industry's addressing of life extension is a natural trend in the maturation of this technology after 20 years of commercial operation. With increasing emphasis on how plants are operated, and less on how to build them, attention is turning on to maximizing the use of these substantial investments. The first studies of life extension were conducted in the period from 1978 and 1982. These were motivated by the initiation, by the Nuclear Regulatory Commission (NRC), of studies to support decommissioning rulemaking. The basic conclusions of those early studies that life extension is feasible and worth pursuing have not been changed by the much more extensive investigations that have since been conducted. From an engineering perspective, life extension for nuclear plants is fundamentally the same as for fossil plants

  12. newspapers' agricultural agenda setting and extension agents ...

    African Journals Online (AJOL)

    p2333147

    Keywords: Newspapers', agricultural, extension agents' agenda setting. ABSTRACT ... from the priorities of political or other interest groups to the news priorities of media ... people. The questions that arise are-: what are the sources operating for ... The ADPs presently adopt the training and visit (T & V) system of extension.

  13. Creating Teams Increases Extension Educator Productivity

    Science.gov (United States)

    Chalker-Scott, Linda; Daniels, Catherine H.; Martini, Nicole

    2016-01-01

    The Garden Team at Washington State University is a transdisciplinary group of faculty, staff, and students with expertise in applied plant and soil sciences and an interest in Extension education. The team's primary mission is to create current, relevant, and peer-reviewed materials as Extension publications for home gardeners. The average yearly…

  14. Dettol: Managing Brand Extensions

    OpenAIRE

    Anand Kumar Jaiswal; Arpita Srivastav; Dhwani Kothari

    2009-01-01

    This case is about evolution of a parent brand and its subsequent extensions into different product categories. Dettol as a brand has immense trust and loyalty from the consumers. Since the 1930s when Dettol was introduced in India, it has occupied a distinct position in the mind of its consumers. To achieve fast growth and leverage the strong brand equity of Dettol, Reckitt Benckiser India Limited (RBIL) rolled out a number of brand extensions. Some of these extensions such as Dettol soap an...

  15. X-Band Electron Paramagnetic Resonance Comparison of Mononuclear Mn(IV)-oxo and Mn(IV)-hydroxo Complexes and Quantum Chemical Investigation of Mn(IV) Zero-Field Splitting.

    Science.gov (United States)

    Leto, Domenick F; Massie, Allyssa A; Colmer, Hannah E; Jackson, Timothy A

    2016-04-04

    X-band electron paramagnetic resonance (EPR) spectroscopy was used to probe the ground-state electronic structures of mononuclear Mn(IV) complexes [Mn(IV)(OH)2(Me2EBC)](2+) and [Mn(IV)(O)(OH)(Me2EBC)](+). These compounds are known to effect C-H bond oxidation reactions by a hydrogen-atom transfer mechanism. They provide an ideal system for comparing Mn(IV)-hydroxo versus Mn(IV)-oxo motifs, as they differ by only a proton. Simulations of 5 K EPR data, along with analysis of variable-temperature EPR signal intensities, allowed for the estimation of ground-state zero-field splitting (ZFS) and (55)Mn hyperfine parameters for both complexes. From this analysis, it was concluded that the Mn(IV)-oxo complex [Mn(IV)(O)(OH)(Me2EBC)](+) has an axial ZFS parameter D (D = +1.2(0.4) cm(-1)) and rhombicity (E/D = 0.22(1)) perturbed relative to the Mn(IV)-hydroxo analogue [Mn(IV)(OH)2(Me2EBC)](2+) (|D| = 0.75(0.25) cm(-1); E/D = 0.15(2)), although the complexes have similar (55)Mn values (a = 7.7 and 7.5 mT, respectively). The ZFS parameters for [Mn(IV)(OH)2(Me2EBC)](2+) were compared with values obtained previously through variable-temperature, variable-field magnetic circular dichroism (VTVH MCD) experiments. While the VTVH MCD analysis can provide a reasonable estimate of the magnitude of D, the E/D values were poorly defined. Using the ZFS parameters reported for these complexes and five other mononuclear Mn(IV) complexes, we employed coupled-perturbed density functional theory (CP-DFT) and complete active space self-consistent field (CASSCF) calculations with second-order n-electron valence-state perturbation theory (NEVPT2) correction, to compare the ability of these two quantum chemical methods for reproducing experimental ZFS parameters for Mn(IV) centers. The CP-DFT approach was found to provide reasonably acceptable values for D, whereas the CASSCF/NEVPT2 method fared worse, considerably overestimating the magnitude of D in several cases. Both methods were poor in

  16. Extensions of the standard model

    International Nuclear Information System (INIS)

    Ramond, P.

    1983-01-01

    In these lectures we focus on several issues that arise in theoretical extensions of the standard model. First we describe the kinds of fermions that can be added to the standard model without affecting known phenomenology. We focus in particular on three types: the vector-like completion of the existing fermions as would be predicted by a Kaluza-Klein type theory, which we find cannot be realistically achieved without some chiral symmetry; fermions which are vector-like by themselves, such as do appear in supersymmetric extensions, and finally anomaly-free chiral sets of fermions. We note that a chiral symmetry, such as the Peccei-Quinn symmetry can be used to produce a vector-like theory which, at scales less than M/sub W/, appears to be chiral. Next, we turn to the analysis of the second hierarchy problem which arises in Grand Unified extensions of the standard model, and plays a crucial role in proton decay of supersymmetric extensions. We review the known mechanisms for avoiding this problem and present a new one which seems to lead to the (family) triplication of the gauge group. Finally, this being a summer school, we present a list of homework problems. 44 references

  17. Spacetime extensions Pt. 1

    International Nuclear Information System (INIS)

    Racz, I.

    1991-09-01

    The problem of the existence of local extensions of spacetime is considered. It is shown that for a spacetime including an incomplete inextendible non-coiling causal geodesic curve there exists a particular C k (resp. C k- ) local extension provided that the curvature and its covariant derivatives are well behaved up to order k + 1 (resp. k) along a family of causal geodetics (around the chosen one). (R.P.) 15 refs

  18. Type extension trees

    DEFF Research Database (Denmark)

    Jaeger, Manfred

    2006-01-01

    We introduce type extension trees as a formal representation language for complex combinatorial features of relational data. Based on a very simple syntax this language provides a unified framework for expressing features as diverse as embedded subgraphs on the one hand, and marginal counts...... of attribute values on the other. We show by various examples how many existing relational data mining techniques can be expressed as the problem of constructing a type extension tree and a discriminant function....

  19. Less extensive surgery compared to extensive surgery

    DEFF Research Database (Denmark)

    Lauszus, Finn F; Petersen, Astrid C; Neumann, Gudrun

    2014-01-01

    -up by hospital data files, general practitioner, death certificate, and autopsy report. Revision of histopathology by a single pathologist. Main outcome measures: Survival and relapse by clinical data, stage, and type of surgery. RESULTS: The incidence of AGCT was 1.37 per year per 100,000 women (95% CI: 1.08, 1.......68). The median follow-up time was 15 years and for the 79 surviving women 22 years. Stage I was found in 94% of cases. Relapse occurred in 24% of women in stage I and 100% of the other stages. Survival in stage I was 95%, 89% and 84% after 5, 10 and 20 years respectively. Increased survival of stage I......: The survival of women was better in AGCT than in epithelial ovarian tumor. Age and type of surgery, besides stage, influenced survival. Total abdominal hysterectomy and bilateral salpingo-oophorectomy is the recommended treatment with advancing age. At younger age less extensive surgery was associated...

  20. Quantum-chemical evaluation of the lability of π-electronic systems in N-benzoyl derivatives of phosphorus and sulfur imines

    International Nuclear Information System (INIS)

    Egorov, Yu.P.; Pen'kovskii, V.V.; Boldeskul, I.E.

    1986-01-01

    The charges on atoms, the bond indices, their components, and the energies of the highest occupied π orbitals of four N-benzoyl derivatives of phosphorus and sulfur imines have been calculated by the CNDO/2 method in an spd basis. According to the results obtained, the π system of a bridging sulfur-nitrogen group is more labile than a phosphorus-nitrogen group, in agreement with the experimental evaluations of the transmission of the electronic effects of substituents in these systems. An interpretation of this lability has been given

  1. DFTB3: Extension of the self-consistent-charge density-functional tight-binding method (SCC-DFTB).

    Science.gov (United States)

    Gaus, Michael; Cui, Qiang; Elstner, Marcus

    2012-04-10

    The self-consistent-charge density-functional tight-binding method (SCC-DFTB) is an approximate quantum chemical method derived from density functional theory (DFT) based on a second-order expansion of the DFT total energy around a reference density. In the present study we combine earlier extensions and improve them consistently with, first, an improved Coulomb interaction between atomic partial charges, and second, the complete third-order expansion of the DFT total energy. These modifications lead us to the next generation of the DFTB methodology called DFTB3, which substantially improves the description of charged systems containing elements C, H, N, O, and P, especially regarding hydrogen binding energies and proton affinities. As a result, DFTB3 is particularly applicable to biomolecular systems. Remaining challenges and possible solutions are also briefly discussed.

  2. Quantum chemical study of regular and irregular geometries of MgO nanoclusters : Effects on magnetizability, electronic properties and physical characteristics

    NARCIS (Netherlands)

    Manzetti, Sergio; Yakovlev, Alexei

    2017-01-01

    Advanced materials and surfaces are key components in nanotechnology and are applied by their magnetizable and spintronic properties, high-frequency scattering, and properties attributing to nanoelectronics and nanomagnetic components. Earth oxides are a group of materials with catalytic effects in

  3. Subring Depth, Frobenius Extensions, and Towers

    Directory of Open Access Journals (Sweden)

    Lars Kadison

    2012-01-01

    Full Text Available The minimum depth d(B,A of a subring B⊆A introduced in the work of Boltje, Danz and Külshammer (2011 is studied and compared with the tower depth of a Frobenius extension. We show that d(B,A < ∞ if A is a finite-dimensional algebra and Be has finite representation type. Some conditions in terms of depth and QF property are given that ensure that the modular function of a Hopf algebra restricts to the modular function of a Hopf subalgebra. If A⊇B is a QF extension, minimum left and right even subring depths are shown to coincide. If A⊇B is a Frobenius extension with surjective Frobenius, homomorphism, its subring depth is shown to coincide with its tower depth. Formulas for the ring, module, Frobenius and Temperley-Lieb structures are noted for the tower over a Frobenius extension in its realization as tensor powers. A depth 3 QF extension is embedded in a depth 2 QF extension; in turn certain depth n extensions embed in depth 3 extensions if they are Frobenius extensions or other special ring extensions with ring structures on their relative Hochschild bar resolution groups.

  4. Extension agents and conflict narratives

    DEFF Research Database (Denmark)

    Bond, Jennifer Lauren

    2016-01-01

    Purpose: This work investigated the narratives of development extensionists in relation to natural resource conflict, in order to understand the competing discourses surrounding the wicked problems of natural resource management in Laikipia County, Kenya. Methodology: Q methodology was used...... to elicit the conflict narratives present among extension professionals. A concourse of 221 statements were devised from interviews and group discussions with key informants and a final sample of 49 statements was used for the sorting. Thirteen Q-sorts were undertaken with among rural extension...... professionals from government, non-government, faith-based and private organizations. Findings: Four factors were elicited from the data, labelled—A: ‘Improved Leadership’; B: ‘Resource-centred conflict’; C: ‘Improved Governance’; and D: ‘Improved Management’. Practical Implications: Narratives of neo...

  5. Evidence for excited state intramolecular charge transfer reaction in donor-acceptor molecule 5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid methyl ester: Experimental and quantum chemical approach

    International Nuclear Information System (INIS)

    Kumar Paul, Bijan; Samanta, Anuva; Kar, Samiran; Guchhait, Nikhil

    2010-01-01

    Intramolecular charge transfer (ICT) reaction has been investigated in 5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid methyl ester (DPDAME) using spectroscopic techniques. The molecule DPDAME shows local emission in non-polar solvent and dual emission in polar solvents. Solvatochromic effects on the Stokes shifted emission band clearly demonstrate the charge transfer character of the excited state. Quantum chemical calculations have been performed at Hartree-Fock (HF) and density functional theoretical (DFT) levels to correlate the experimental findings. Potential energy curves (PECs) for the ICT reaction have been evaluated along the donor twist angle at DFT and time dependent density functional theory (TDDFT) levels for the ground and excited states, respectively, using B3LYP hybrid functional and 6-31G** basis set. The solvent effects on the spectral properties have been explored theoretically at the same level with time dependent density functional theory-polarized continuum model (TDDFT-PCM) and the theoretical results are found to well substantiate the solvent polarity dependent Stokes shifted emission of DPDAME. Huge enhancement of dipole moment (Δμ=16.42 D) of the molecule following photoexcitation dictates the highly polar character of the excited state. Although elucidation of PECs does not exactly predict the operation of ICT according to twisted intramolecular charge transfer (TICT) model in DPDAME, lowering of vertical transition energy as a function of the donor twist coordinate scripts the occurrence of red shifted emission as observed experimentally.

  6. Spectroscopic (FT-IR, FT-Raman, and UV-visible) and quantum chemical studies on molecular geometry, Frontier molecular orbitals, NBO, NLO and thermodynamic properties of 1-acetylindole.

    Science.gov (United States)

    Shukla, Vikas K; Al-Abdullah, Ebtehal S; El-Emam, Ali A; Sachan, Alok K; Pathak, Shilendra K; Kumar, Amarendra; Prasad, Onkar; Bishnoi, Abha; Sinha, Leena

    2014-12-10

    Quantum chemical calculations of ground state energy, geometrical structure and vibrational wavenumbers of 1-acetylindole were carried out using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. The FT-IR and FT-Raman spectra were recorded in the condensed state. The fundamental vibrational wavenumbers were calculated and a good correlation between experimental and scaled calculated wavenumbers has been accomplished. Electric dipole moment, polarizability and first static hyperpolarizability values of 1-acetylindole have been calculated at the same level of theory and basis set. The results show that the 1-acetylindole molecule possesses nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV-Visible spectrum of the molecule was recorded in the region 200-500nm and the electronic properties like HOMO and LUMO energies and composition were obtained using TD-DFT method. The calculated energies and oscillator strengths are in good correspondence with the experimental data. The thermodynamic properties of the compound under investigation were calculated at different temperatures. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Comparison of Model Systems (M+n·[CrX63−] and M3CrX6 + 18MX Based on Quantum-Chemical Calculations (X: F, Cl

    Directory of Open Access Journals (Sweden)

    Vyacheslav Kremenetsky

    2016-01-01

    Full Text Available On the basis of quantum-chemical calculations the most stable particle compositions are estimated in such model systems as (M+n·[CrCl6] and M3CrCl6 + 18MCl (M = Na, K, and Cs. In all systems these particles are positively charged. For systems (M+n·[CrCl6], (M+n·[CrF6], M3CrF6 + 18MCl, M3CrF6 + 18MF, and M3CrCl6 + 18MCl (M = Na, K, and Cs a number of energy parameters characterizing the state of the system before and after electron transfer are calculated. The results indicate the possibility of electron transfer from the cathode to the melt system, which is in the initial state. However, this possibility cannot be realized in systems where LUMOs (lowest unoccupied molecular orbitals have purely ligand character. In this case, the preliminary deformation of a cationic shell of electroactive species is required; it transforms the initial system to the transition state. However, in all considered systems the search of the transition state should be carried close to the initial state Pi. This greatly simplifies a problem and transforms it from a purely theoretical sphere to the field of practical tasks that do not require exceptional cost of computer time.

  8. Dual-and quad-core tartarato-complexes of vanadium(V): quantum-chemical calculations of structural and spectroscopic parameters; Dvojjadrove a stvorjadrove tartaratokomplexy vanadu(V): kvantovochemicke vypocty strukturnych a spektroskopickych parametrov

    Energy Technology Data Exchange (ETDEWEB)

    Oreskova, G; Simunek, J; Noga, J [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia)

    2012-04-25

    Geometry and spectral properties of the complex anion [V4O8 ((R, R)-tart) 2] 4 - were theoretically investigated by quantum-chemical calculations in gas phase or by using PCM model. Geometry optimization was done by us using the functionals BP86, B3LYP as well as by functional class M06. The best match with experimental data was given by M06 functionals. In the optimal geometry we assigned to individual relation a type of vibration active in infrared spectra. Wave numbers calculated by BP86 method are in a very good agreement with experiment, unlike the M06 functionals. For anion in the experimental geometry, we determined an area of maximum absorption (UV-VIS spectra) by calculating excitation energies. The calculated values of the absorption maxima are in a very good agreement with experiment and they successfully explain the celerity of the complex. For geometry optimized by BP86 functional in a gas phase as well as including the solvent we calculated NMR chemical shifts by B3LYP and B3PW91 functionals. The best results with respect to the experiment were given by the method B3PW91 for optimized geometry in a gas phase. (authors)

  9. Organometallic derivatives of furan. LII. Synthesis of carbofunctional furylsilanes and their 1H, 13C, and 29Si NMR spectroscopic and quantum-chemical investigation

    International Nuclear Information System (INIS)

    Lukevits, E.; Erchak, N.P.; Castro, I.; Popelis, Yu.Yu.; Kozyrev, A.K.; Anoshkin, V.I.; Kovalev, I.F.

    1986-01-01

    Under the standard conditions for the synthesis of furan compounds it is possible to obtain the carbofunctional derivatives of silylated furfural with retention of the trimethylsilyl group in the ring. By NMR and CNDO/2 LCAO MO methods and also as a result of the investigation of the chemical characteristics of silylated furfural and its carbofunctional derivatives it was established that the introduction of a trimethylsilyl group at position 5 of the furan ring does not change the reactivity of the carbofunctional substituents at position 2. The electronic effects of the substituents are hardly transmitted through the furan ring at all. The effect of substituents in the carbofunctional furylsilanes on the electronic structure of the ring is additive

  10. Android Access Control Extension

    Directory of Open Access Journals (Sweden)

    Anton Baláž

    2015-12-01

    Full Text Available The main objective of this work is to analyze and extend security model of mobile devices running on Android OS. Provided security extension is a Linux kernel security module that allows the system administrator to restrict program's capabilities with per-program profiles. Profiles can allow capabilities like network access, raw socket access, and the permission to read, write, or execute files on matching paths. Module supplements the traditional Android capability access control model by providing mandatory access control (MAC based on path. This extension increases security of access to system objects in a device and allows creating security sandboxes per application.

  11. Life extension economic analysis

    International Nuclear Information System (INIS)

    Smithling, A.P.

    1992-01-01

    Life extension economic analyses of fossil fueled power plants need the development of consistent methods which consider the capital costs associated with component replacement or repair and estimates of normal station capital expenditures over the units remaining life. In order to link capital and production costs, Niagra Mohawk Power Corp. develops most and worst cases. A most case includes capital components that would definitely need replacement or modification for life extension. The worst case scenario contains must case capital costs plus various components which may need replacement or modification. In addition, two forecasted conditions are used, base case capacity and low capacity

  12. Augmented therapy of extensive Hodgkin's disease: radiation to known disease or prolongation of induction chemotherapy did not improve survival--results of a cancer and leukemia group B study

    International Nuclear Information System (INIS)

    Coleman, Morton; Rafla, Sameer; Propert, Kathleen J.; Glicksman, Arvin; Peterson, Bruce; Nissen, Nis; Brunner, Kurt; Holland, James F.; Anderson, James R.; Gottlieb, Arlan; Kaufman, Thomas

    1998-01-01

    Purpose: This prospective randomized trial in extensive untreated Hodgkin's disease was undertaken to assess the potential benefit of augmented therapy (12 months chemotherapy or radiation to known disease) compared to standard 6 months chemotherapy. Patient and Methods: A total of 258 patients, mostly Stage IV, were randomized to four treatment regimens consisting of six cycles of CCNU, vinblastine, procarbazine, and prednisone (CVPP); 12 cycles of CVPP; six cycles of CVPP followed by 25 Gy radiotherapy; or three cycles CVPP, 25 Gy radiotherapy, and three cycles CVPP. Results: Complete remissions were achieved in 65% of all patients. A 58% overall 5-year survival rate was obtained. Relapses in irradiated areas of known disease occurred in only 6% of responding patients. There was, however, no statistical difference in response frequency, disease-free survival, or overall survival among the four regimens. Elderly patients responded less frequently. Conclusion: While radiotherapy provided control of local (known) disease, no impact on overall survival was apparent. Likewise, doubling the duration of chemotherapy did not improve response or survival. Augmentation of therapy with either radiotherapy or more chemotherapy in this study was of no benefit compared to the standard 6 months of treatment

  13. Crystal and molecular structures of benzo[4,5]imidazo[1,2-c]quinazolin-6-one and 10-carboxybenzo[4,5]imidazo[1,2-c]quinazolin-6-one: A quantum-chemical study of their tautomerism

    International Nuclear Information System (INIS)

    Koval’chukova, O. V.; Stash, A. I.; Strashnov, P. V.; Neborak, E. V.; Strashnova, S. B.; Zaitsev, B. E.

    2011-01-01

    Benzo[4,5]imidazo[1,2-c]quinazolin-6-one and 10-carboxybenzo[4,5]imidazo[1,2-c]quinazolin-6-one were isolated in the crystalline state and studied by X-ray diffraction. The crystal and molecular structures of these compounds were determined by X-ray diffraction. The energy characteristics of the tautomeric and ionic forms were calculated by the quantum-chemical PM3 method.

  14. Mobile Applications for Extension

    Science.gov (United States)

    Drill, Sabrina L.

    2012-01-01

    Mobile computing devices (smart phones, tablets, etc.) are rapidly becoming the dominant means of communication worldwide and are increasingly being used for scientific investigation. This technology can further our Extension mission by increasing our power for data collection, information dissemination, and informed decision-making. Mobile…

  15. Structure of pyridine and quinoline vinyl ethers according to data from 1H and 13C NMR spectra and quantum-chemical calculations

    International Nuclear Information System (INIS)

    Afonin, A.V.; Voronov, V.K.; Andriankov, M.A.; Danovich, D.K.

    1987-01-01

    A systematic investigation of the structure of the vinyl ethers of heterocyclic compounds has not been undertaken. The present work was devoted to investigation of the stereochemical and electronic structure of the vinyl ethers of pyridine and quinoline. The PMR spectra of the samples were recorded for 5% solutions in deuterochloroform on a Tesla BS-497 spectrometer at 100 MHz. The 13 C NMR spectra were recorded on a Tesla BS-567A spectrometer at 25.1 MHz in deuterochloroform with the samples at concentrations of 30%. The internal standard was HMDS. The vinyl ethers of pyridine and quinoline exist preferentially in the nonplanar S-trans conformation. In the vinyl esters of pyridine and quinoline the p-π conjugation is concurrent in nature and depends on the position of the vinyloxy group in the heterocycle

  16. Extension arm facilitated pegylation of alphaalpha-hemoglobin with modifications targeted exclusively to amino groups: functional and structural advantages of free Cys-93(beta) in the PEG-Hb adduct.

    Science.gov (United States)

    Li, Dongxia; Hu, Tao; Manjula, Belur N; Acharya, Seetharama A

    2009-11-01

    Cys-93(beta) of hemoglobin (Hb) was reversibly protected as a mixed disulfide with thiopyridine during extension arm facilitated (EAF) PEGylation and its influence on the structural and functional properties of the EAF-PEG-Hb has been investigated. Avoiding PEGylation of Cys-93(beta) in the EAF-PEG-Hb lowers the level of perturbation of heme pocket, alpha1beta2 interface, autoxidation, heme loss, and the O(2) affinity, as compared to the EAF-PEG-Hb with PEGylation of Cys-93(beta).The structural and functional advantages of reversible protection of Cys-93(beta) during EAF PEGylation of oxy-Hb has been compared with Euro PEG-Hb generated by EAF PEGylation of deoxy Hb where Cys-93(beta) is free in the final product. The alphaalpha-fumaryl cross-linking and EAF PEGylation targeted exclusively to Lys residues has been combined together for generation of second-generation EAF-PEG-Hb with lower oxygen affinity. The PEG chains engineered on Lys as well as PEGylation of Cys-93(beta) independently contribute to the stabilization of oxy conformation of Hb and hence increase the oxygen affinity of Hb. However, oxygen affinity of the EAF-PEG-alphaalpha-Hb is more sensitive to the presence of PEGylation on Cys-93(beta) than that of the EAF-PEG-Hb. The present modified EAF PEGylation platform is expected to facilitate the design of novel versions of the EAF-PEG-Hbs that can now integrate the advantages of avoiding PEGylation of Cys-93(beta).

  17. Nonradiative Decay Route of Cinnamate Derivatives Studied by Frequency and Time Domain Laser Spectroscopy in the Gas Phase, Matrix Isolation FTIR Spectroscopy and Quantum Chemical Calculations

    Science.gov (United States)

    Ebata, Takayuki

    2017-06-01

    The nonraddiative dececy route involving trans → cis photo-isomerization from the S_1 (ππ*) state has been investigated for several trans-cinnamate derivatives, which are known as sunscreen reagents. We examined two types of substitution effects. One is structural isomer such as ortho-, meta-, and para-hydroxy-methylcinnmate (o-, m-, p-HMC). The S_1 lifetime of p-HMC is less than 8 ps at zero-point level, and it undergoes rapid S_1 → ^1nπ* → T_1 decay via multiple conical intersections. Finally, the trans → cis isomerization proceeds in the T_1 state. On the other hand, both o- and m-HMC show very slow decay. Their S_1 lifetimes are in the order of 100 ps even at the excess energy of 2000-3000 \\wn. The other is the effect of the complexity of ester group in para-subsitituted species, such as para-methoxy-methyl, -ethyl and -2ethylhexyl cinnamate (p-MMC, p-MEC, p-M2EHC). p-MMC and p-MEC show sharp S_0 → S_1 (ππ*) vibronic bands, while p-M2EHC shows only broad structureless feature even under the jet-cooled condition. In addition, we found that the S_0 → ^1nπ* absorption appears at 1000 \\wn below the S_0 → S_1 (ππ*) transition in p-MEC and p-M2EHC, but not in p-MMC. Thus, the complexity of the ester group is very important for the appearance of the ^1nπ* state.

  18. The quantum chemical causality of pMHC-TCR biological avidity: Peptide atomic coordination data and the electronic state of agonist N termini

    Directory of Open Access Journals (Sweden)

    Georgios S.E. Antipas

    2015-06-01

    Full Text Available The quantum state of functional avidity of the synapse formed between a peptide-Major Histocompatibility Complex (pMHC and a T cell receptor (TCR is a subject not previously touched upon. Here we present atomic pair correlation meta-data based on crystalized tertiary structures of the Tax (HTLV-1 peptide along with three artificially altered variants, all of which were presented by the (Class I HLA-A201 protein in complexation with the human (CD8+ A6TCR. The meta-data reveal the existence of a direct relationship between pMHC-TCR functional avidity (agonist/antagonist and peptide pair distribution function (PDF. In this context, antagonist peptides are consistently under-coordinated in respect to Tax. Moreover, Density Functional Theory (DFT datasets in the BLYP/TZ2P level of theory resulting from relaxation of the H species on peptide tertiary structures reveal that the coordination requirement of agonist peptides is also expressed as a physical observable of the protonation state of their N termini: agonistic peptides are always found to retain a stable ammonium (NH3+ terminal group while antagonist peptides are not.

  19. Experimental and quantum chemical studies of a new organic proton transfer compound, 1H-imidazole-3-ium-3-hydroxy-2,4,6-trinitrophenolate

    Science.gov (United States)

    Dhamodharan, P.; Sathya, K.; Dhandapani, M.

    2018-02-01

    A new proton transfer compound, 1H-imidazole-3-ium-3-hydroxy-2,4,6-trinitrophenolate (IMHTP), was crystallized by slow evaporation-solution growth technique. 1H and 13C NMR spectral studies confirm the molecular structure of the grown crystal. Single crystal X-ray diffraction study confirms that IMHTP crystallizes in monoclinic system with space group P21/c. Thermal curves (TG/DTA) show that the material is thermally stable up to 198 °C. The crystal emits fluorescence at 510 nm, proving its utility in making green light emitting materials in optical applications. The stable molecular structure was optimized by Gaussian 09 program with B3LYP/6-311++G(d,p) level of basis set. The frontier molecular orbital study shows that the charge transfer interaction occurs within the complex. The calculated first-order hyperpolarizability value of IMHTP is 44 times higher than that the reference material, urea. The electrostatic potential map was used to probe into electrophilic and nucleophilic reactive sites present in the molecule.

  20. Spectroscopic [FT-IR and FT-Raman] and molecular modeling (MM) study of benzene sulfonamide molecule using quantum chemical calculations

    Science.gov (United States)

    Vinod, K. S.; Periandy, S.; Govindarajan, M.

    2016-07-01

    The spectroscopic and molecular modeling (MM) study includes, FT-IR, FT-Raman and 13C NMR and 1H NMR spectra of the Benzene sulfonamide were recorded for the analysis. The observed experimental and theoretical frequencies (IR and Raman) were assigned according to their distinctive region. The present study of this title molecule have been carried out by hybrid computational calculations of HF and DFT (B3LYP) methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets and the corresponding results are tabulated. The structural modifications of the compound due to the substitutions of NH2 and SO2 were investigated. The minimum energy conformers of the compound were studied using conformational analysis. The alternations of the vibrational pattern of the base structure related to the substitutions were analyzed. The thermodynamic parameters (such as zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment) of Benzene sulfonamide have been calculated. The donor acceptor interactions of the compound and the corresponding UV transitions are found out using NBO analysis. The NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts related to TMS were compared. A quantum computational study on the electronic and optical properties absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by HF and DFT methods. The energy gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand group. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase and

  1. Extension without Cut

    OpenAIRE

    Straßburger , Lutz

    2012-01-01

    International audience; In proof theory one distinguishes sequent proofs with cut and cut-free sequent proofs, while for proof complexity one distinguishes Frege-systems and extended Frege-systems. In this paper we show how deep inference can provide a uniform treatment for both classifications, such that we can define cut-free systems with extension, which is neither possible with Frege-systems, nor with the sequent calculus. We show that the propositional pigeon-hole principle admits polyno...

  2. Theoretical study of the electronic structure of f-element complexes by quantum chemical methods; Analyse de la structure electronique des complexes contenant des elements F par des methodes de la chimie quantique

    Energy Technology Data Exchange (ETDEWEB)

    Vetere, V

    2002-09-15

    This thesis is related to comparative studies of the chemical properties of molecular complexes containing lanthanide or actinide trivalent cations, in the context of the nuclear waste disposal. More precisely, our aim was a quantum chemical analysis of the metal-ligand bonding in such species. Various theoretical approaches were compared, for the inclusion of correlation (density functional theory, multiconfigurational methods) and of relativistic effects (relativistic scalar and 2-component Hamiltonians, relativistic pseudopotentials). The performance of these methods were checked by comparing computed structural properties to published experimental data, on small model systems: lanthanide and actinide tri-halides and on X{sub 3}M-L species (X=F, Cl; M=La, Nd, U; L = NH{sub 3}, acetonitrile, CO). We have thus shown the good performance of density functionals combined with a quasi-relativistic method, as well as of gradient-corrected functionals associated with relativistic pseudopotentials. In contrast, functionals including some part of exact exchange are less reliable to reproduce experimental trends, and we have given a possible explanation for this result . Then, a detailed analysis of the bonding has allowed us to interpret the discrepancies observed in the structural properties of uranium and lanthanides complexes, based on a covalent contribution to the bonding, in the case of uranium(III), which does not exist in the lanthanide(III) homologues. Finally, we have examined more sizeable systems, closer to experimental species, to analyse the influence of the coordination number, of the counter-ions and of the oxidation state of uranium, on the metal-ligand bonding. (author)

  3. Lubin-Tate extensions, an elementary approach

    International Nuclear Information System (INIS)

    Ershov, Yu L

    2007-01-01

    We give an elementary proof of the assertion that the Lubin-Tate extension L≥K is an Abelian extension whose Galois group is isomorphic to U K /N L/K (U L ) for arbitrary fields K that have Henselian discrete valuation rings with finite residue fields. The term 'elementary' only means that the proofs are algebraic (that is, no transcedental methods are used)

  4. Abelian groups

    CERN Document Server

    Fuchs, László

    2015-01-01

    Written by one of the subject’s foremost experts, this book focuses on the central developments and modern methods of the advanced theory of abelian groups, while remaining accessible, as an introduction and reference, to the non-specialist. It provides a coherent source for results scattered throughout the research literature with lots of new proofs. The presentation highlights major trends that have radically changed the modern character of the subject, in particular, the use of homological methods in the structure theory of various classes of abelian groups, and the use of advanced set-theoretical methods in the study of undecidability problems. The treatment of the latter trend includes Shelah’s seminal work on the undecidability in ZFC of Whitehead’s Problem; while the treatment of the former trend includes an extensive (but non-exhaustive) study of p-groups, torsion-free groups, mixed groups, and important classes of groups arising from ring theory. To prepare the reader to tackle these topics, th...

  5. Continuous multivariate exponential extension

    International Nuclear Information System (INIS)

    Block, H.W.

    1975-01-01

    The Freund-Weinman multivariate exponential extension is generalized to the case of nonidentically distributed marginal distributions. A fatal shock model is given for the resulting distribution. Results in the bivariate case and the concept of constant multivariate hazard rate lead to a continuous distribution related to the multivariate exponential distribution (MVE) of Marshall and Olkin. This distribution is shown to be a special case of the extended Freund-Weinman distribution. A generalization of the bivariate model of Proschan and Sullo leads to a distribution which contains both the extended Freund-Weinman distribution and the MVE

  6. Extensive air showers

    CERN Document Server

    Rao, M V S

    1997-01-01

    Ultrahigh energy cosmic rays carry information about their sources and the intervening medium apart from providing a beam of particles for studying certain features of high energy interactions currently inaccessible at man-made accelerators. They can at present be studied only via the extensive air showers (EAS's) they generate while passing through the Earth's atmosphere, since their fluxes are too low for the experiments of limited capability flown in balloons and satellites. The EAS is generated by a series of interactions of the primary cosmic ray and its progeny with the atmospheric nucle

  7. Quantum-chemical modeling of smectite clays

    Science.gov (United States)

    Aronowitz, S.; Coyne, L.; Lawless, J.; Rishpon, J.

    1982-01-01

    A self-consistent charge extended Hueckel program is used in modeling isomorphic substitution of Al(3+) by Na(+), K(+), Mg(2+), Fe(2+), and Fe(3+) in the octahedral layer of a dioctahedral smectite clay, such as montmorillonite. Upon comparison of the energies involved in the isomorphic substitution, it is found that the order for successful substitution is as follows: Al(3+), Fe(3+), Mg(2+), Fe(2+), Na(+), which is equivalent to Ca(2+), and then K(+). This ordering is found to be consistent with experimental observation. The calculations also make it possible to determine the possible penetration of metal ions into the clay's 2:1 crystalline layer. For the cases studied, this type of penetration can occur at elevated temperatures into regions where isomorphic substitution has occurred with metal ions that bear a formal charge of less than 3+. The computed behavior of the electronic structure in the presence of isomorphic substitution is found to be similar to behavior associated with semiconductors.

  8. Electrochemical, surface analytical and quantum chemical studies ...

    Indian Academy of Sciences (India)

    subject of numerous studies due to their high technological value and wide range .... Mulliken population analysis of atoms in triazole derivatives, depending on the ... 2102–0003) with an accelerating voltage of 20 kV, at a scan speed=slow 5 and ... the corrosion rate can also be determined by Tafel extra- polation of either ...

  9. Molecular dynamics simulations and quantum chemical calculations ...

    African Journals Online (AJOL)

    Molecular dynamic simulation results indicate that the imidazoline derivative molecules uses the imidazoline ring to effectively adsorb on the surface of iron, with the alkyl hydrophobic tail forming an n shape (canopy like covering) at geometry optimization and at 353 K. The n shape canopy like covering to a large extent may ...

  10. SOME QUANTUM CHEMICAL STUDY ON THE STRUCTURAL ...

    African Journals Online (AJOL)

    Preferred Customer

    unoccupied molecular orbital (LUMO) energy, HOMO-LUMO gap energy, RHF energy, some of important bond ..... Sobczak, J.M.; Glowiak, T.; Zio, J.J. Transition Met.Chem. ... Wiley-VCH: Velang GmbH, Weinheim (Germany); 2000. (b) Becke ...

  11. On loop extensions and cohomology of loops

    OpenAIRE

    Benítez, Rolando Jiménez; Meléndez, Quitzeh Morales

    2015-01-01

    In this paper are defined cohomology-like groups that classify loop extensions satisfying a given identity in three variables for association identities, and in two variables for the case of commutativity. It is considered a large amount of identities. This groups generalize those defined in works of Nishigori [2] and of Jhonson and Leedham-Green [4]. It is computed the number of metacyclic extensions for trivial action of the quotient on the kernel in one particular case for left Bol loops a...

  12. Coal Combustion Products Extension Program

    Energy Technology Data Exchange (ETDEWEB)

    Tarunjit S. Butalia; William E. Wolfe

    2006-01-11

    40% by 2010, the CCP Extension Program be expanded at OSU, with support from state and federal agencies, utilities, trade groups, and the university, to focus on the following four specific areas of promise: (a) Expanding use in proven areas (such as use of fly ash in concrete); (b) Removing or reducing regulatory and perceptual barriers to use (by working in collaboration with regulatory agencies); (c) Developing new or under-used large-volume market applications (such as structural fills); and (d) Placing greater emphasis on FGD byproducts utilization.

  13. Ground System Extensibility Considerations

    Science.gov (United States)

    Miller, S. W.; Greene, E.

    2017-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners, such as NASA's Earth Observation System (EOS), NOAA's current POES, the Japan Aerospace Exploration Agency's (JAXA) Global Change Observation Mission - Water (GCOM-W1), and DoD's Defense Meteorological Satellite Program (DMSP). The CGS provides a wide range of support to a number of national and international missions, including command and control, mission management, data acquisition and routing, and environmental data processing and distribution. The current suite of CGS-supported missions has demonstrated the value of interagency and international partnerships to address global observation needs. With its established infrastructure and existing suite of missions, the CGS is extensible to a wider array of potential new missions. This paper will describe how the inherent scalability and extensibility of the CGS enables the addition of these new missions, with an eye on global enterprise needs in the 2020's and beyond.

  14. Bond energies of ThO+ and ThC+: A guided ion beam and quantum chemical investigation of the reactions of thorium cation with O2 and CO

    Science.gov (United States)

    Cox, Richard M.; Citir, Murat; Armentrout, P. B.; Battey, Samuel R.; Peterson, Kirk A.

    2016-05-01

    Kinetic energy dependent reactions of Th+ with O2 and CO are studied using a guided ion beam tandem mass spectrometer. The formation of ThO+ in the reaction of Th+ with O2 is observed to be exothermic and barrierless with a reaction efficiency at low energies of k/kLGS = 1.21 ± 0.24 similar to the efficiency observed in ion cyclotron resonance experiments. Formation of ThO+ and ThC+ in the reaction of Th+ with CO is endothermic in both cases. The kinetic energy dependent cross sections for formation of these product ions were evaluated to determine 0 K bond dissociation energies (BDEs) of D0(Th+-O) = 8.57 ± 0.14 eV and D0(Th+-C) = 4.82 ± 0.29 eV. The present value of D0 (Th+-O) is within experimental uncertainty of previously reported experimental values, whereas this is the first report of D0 (Th+-C). Both BDEs are observed to be larger than those of their transition metal congeners, TiL+, ZrL+, and HfL+ (L = O and C), believed to be a result of lanthanide contraction. Additionally, the reactions were explored by quantum chemical calculations, including a full Feller-Peterson-Dixon composite approach with correlation contributions up to coupled-cluster singles and doubles with iterative triples and quadruples (CCSDTQ) for ThC, ThC+, ThO, and ThO+, as well as more approximate CCSD with perturbative (triples) [CCSD(T)] calculations where a semi-empirical model was used to estimate spin-orbit energy contributions. Finally, the ThO+ BDE is compared to other actinide (An) oxide cation BDEs and a simple model utilizing An+ promotion energies to the reactive state is used to estimate AnO+ and AnC+ BDEs. For AnO+, this model yields predictions that are typically within experimental uncertainty and performs better than density functional theory calculations presented previously.

  15. Intramolecular CH···O hydrogen bonds in the AI and BI DNA-like conformers of canonical nucleosides and their Watson-Crick pairs. Quantum chemical and AIM analysis.

    Science.gov (United States)

    Yurenko, Yevgen P; Zhurakivsky, Roman O; Samijlenko, Svitlana P; Hovorun, Dmytro M

    2011-08-01

    The aim of this work is to cast some light on the H-bonds in double-stranded DNA in its AI and BI forms. For this purpose, we have performed the MP2 and DFT quantum chemical calculations of the canonical nucleoside conformers, relative to the AI and BI DNA forms, and their Watson-Crick pairs, which were regarded as the simplest models of the double-stranded DNA. Based on the atoms-in-molecules analysis (AIM), five types of the CH···O hydrogen bonds, involving bases and sugar, were detected numerically from 1 to 3 per a conformer: C2'H···O5', C1'H···O2, C6H···O5', C8H···O5', and C6H···O4'. The energy values of H-bonds occupy the range of 2.3-5.6 kcal/mol, surely exceeding the kT value (0.62 kcal/mol). The nucleoside CH···O hydrogen bonds appeared to "survive" turns of bases against the sugar, sometimes in rather large ranges of the angle values, pertinent to certain conformations, which points out to the source of the DNA lability, necessary for the conformational adaptation in processes of its functioning. The calculation of the interactions in the dA·T nucleoside pair gives evidence, that additionally to the N6H···O4 and N1···N3H canonical H-bonds, between the bases adenine and thymine the third one (C2H···O2) is formed, which, though being rather weak (about 1 kcal/mol), satisfies the AIM criteria of H-bonding and may be classified as a true H-bond. The total energy of all the CH···O nontraditional intramolecular H-bonds in DNA nucleoside pairs appeared to be commensurable with the energy of H-bonds between the bases in Watson-Crick pairs, which implies their possible important role in the DNA shaping.

  16. Bond energies of ThO{sup +} and ThC{sup +}: A guided ion beam and quantum chemical investigation of the reactions of thorium cation with O{sub 2} and CO

    Energy Technology Data Exchange (ETDEWEB)

    Cox, Richard M; Citir, Murat; Armentrout, P. B., E-mail: armentrout@chem.utah.edu [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850 (United States); Battey, Samuel R.; Peterson, Kirk A. [Department of Chemistry, Washington State University, Pullman, Washington 99164-4630 (United States)

    2016-05-14

    Kinetic energy dependent reactions of Th{sup +} with O{sub 2} and CO are studied using a guided ion beam tandem mass spectrometer. The formation of ThO{sup +} in the reaction of Th{sup +} with O{sub 2} is observed to be exothermic and barrierless with a reaction efficiency at low energies of k/k{sub LGS} = 1.21 ± 0.24 similar to the efficiency observed in ion cyclotron resonance experiments. Formation of ThO{sup +} and ThC{sup +} in the reaction of Th{sup +} with CO is endothermic in both cases. The kinetic energy dependent cross sections for formation of these product ions were evaluated to determine 0 K bond dissociation energies (BDEs) of D{sub 0}(Th{sup +}–O) = 8.57 ± 0.14 eV and D{sub 0}(Th{sup +}–C) = 4.82 ± 0.29 eV. The present value of D{sub 0} (Th{sup +}–O) is within experimental uncertainty of previously reported experimental values, whereas this is the first report of D{sub 0} (Th{sup +}–C). Both BDEs are observed to be larger than those of their transition metal congeners, TiL{sup +}, ZrL{sup +}, and HfL{sup +} (L = O and C), believed to be a result of lanthanide contraction. Additionally, the reactions were explored by quantum chemical calculations, including a full Feller-Peterson-Dixon composite approach with correlation contributions up to coupled-cluster singles and doubles with iterative triples and quadruples (CCSDTQ) for ThC, ThC{sup +}, ThO, and ThO{sup +}, as well as more approximate CCSD with perturbative (triples) [CCSD(T)] calculations where a semi-empirical model was used to estimate spin-orbit energy contributions. Finally, the ThO{sup +} BDE is compared to other actinide (An) oxide cation BDEs and a simple model utilizing An{sup +} promotion energies to the reactive state is used to estimate AnO{sup +} and AnC{sup +} BDEs. For AnO{sup +}, this model yields predictions that are typically within experimental uncertainty and performs better than density functional theory calculations presented previously.

  17. Modelling of retention of pesticides in reversed-phase high-performance liquid chromatography: Quantitative structure-retention relationships based on solute quantum-chemical descriptors and experimental (solvatochromic and spin-probe) mobile phase descriptors

    International Nuclear Information System (INIS)

    D'Archivio, Angelo Antonio; Ruggieri, Fabrizio; Mazzeo, Pietro; Tettamanti, Enzo

    2007-01-01

    A quantitative structure-retention relationship (QSRR) analysis based on multilinear regression (MLR) and artificial neural networks (ANNs) is carried out to model the combined effect of solute structure and eluent composition on the retention behaviour of pesticides in isocratic reversed-phase high-performance liquid chromatography (RP-HPLC). The octanol-water partition coefficient and four quantum chemical descriptors (the total dipole moment, the mean polarizability, the anisotropy of the polarizability and a descriptor of hydrogen-bonding based on the atomic charges on acidic and basic chemical functionalities) are considered as solute descriptors. In order to identify suitable mobile phase descriptors, encoding composition-dependent properties of both methanol- and acetonitrile-containing mobile phases, the Kamlet-Taft solvatochromic parameters (polarity-dipolarity, hydrogen-bond acidity and hydrogen-bond basicity, π * , α and β, respectively) and the 14 N hyperfine-splitting constant (a N ) of a spin-probe dissolved in the eluent are examined. A satisfactory description of mobile phase properties influencing the solute retention is provided by a N and β or alternatively π * and β. The two seven-parameter models resulting from combination of a N and β, or π * and β, with the solute descriptors were tested on a set of 26 pesticides representative of 10 different chemical classes in a wide range of mobile phase composition (30-60% (v/v) water-methanol and 30-70% (v/v) water-acetonitrile). Within the explored experimental range, the acidity of the eluent, as quantified by α, is almost constant, and this parameter is in fact irrelevant. The results reveal that a N and π * , that can be considered as interchangeable mobile phase descriptors, are the most influent variables in the respective models. The predictive ability of the proposed models, as tested on an external data set, is quite good (Q 2 close to 0.94) when a MLR approach is used, but the

  18. Modelling of retention of pesticides in reversed-phase high-performance liquid chromatography: Quantitative structure-retention relationships based on solute quantum-chemical descriptors and experimental (solvatochromic and spin-probe) mobile phase descriptors

    Energy Technology Data Exchange (ETDEWEB)

    D' Archivio, Angelo Antonio [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy)]. E-mail: darchivi@univaq.it; Ruggieri, Fabrizio [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy); Mazzeo, Pietro [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy); Tettamanti, Enzo [Dipartimento di Scienze Biomediche Comparate, Universita di Teramo, P.zzale A. Moro 45, 64100 Teramo (Italy)

    2007-06-19

    A quantitative structure-retention relationship (QSRR) analysis based on multilinear regression (MLR) and artificial neural networks (ANNs) is carried out to model the combined effect of solute structure and eluent composition on the retention behaviour of pesticides in isocratic reversed-phase high-performance liquid chromatography (RP-HPLC). The octanol-water partition coefficient and four quantum chemical descriptors (the total dipole moment, the mean polarizability, the anisotropy of the polarizability and a descriptor of hydrogen-bonding based on the atomic charges on acidic and basic chemical functionalities) are considered as solute descriptors. In order to identify suitable mobile phase descriptors, encoding composition-dependent properties of both methanol- and acetonitrile-containing mobile phases, the Kamlet-Taft solvatochromic parameters (polarity-dipolarity, hydrogen-bond acidity and hydrogen-bond basicity, {pi} {sup *}, {alpha} and {beta}, respectively) and the {sup 14}N hyperfine-splitting constant (a {sub N}) of a spin-probe dissolved in the eluent are examined. A satisfactory description of mobile phase properties influencing the solute retention is provided by a {sub N} and {beta} or alternatively {pi} {sup *} and {beta}. The two seven-parameter models resulting from combination of a {sub N} and {beta}, or {pi} {sup *} and {beta}, with the solute descriptors were tested on a set of 26 pesticides representative of 10 different chemical classes in a wide range of mobile phase composition (30-60% (v/v) water-methanol and 30-70% (v/v) water-acetonitrile). Within the explored experimental range, the acidity of the eluent, as quantified by {alpha}, is almost constant, and this parameter is in fact irrelevant. The results reveal that a {sub N} and {pi} {sup *}, that can be considered as interchangeable mobile phase descriptors, are the most influent variables in the respective models. The predictive ability of the proposed models, as tested on an

  19. Utilization pattern of extension tools and methods by Agricultural Extension Agents

    Directory of Open Access Journals (Sweden)

    M Surudhi

    2018-05-01

    Full Text Available A study was conducted in Krishnagiri district of Tamil Nadu state to understand the utilization pattern of extension tools and methods by the agricultural extension agents. As ICT revolution is slowly conquering the rural sector, it becomes imperative that the agricultural extension agents transform themselves to the changing times and develop competencies in utilizing these ICTs.  The study explored the usage of various extension tools and methods by the change agents and the constraints faced in utilizing them. The findings revealed that the extension functionaries frequently used the individual contact methods viz., telephone, office calls and farm and home visits in the process of transfer of technology. Least efforts were shown in sending SMS based communication. Meetings were the common and frequently adopted group contact method. Demonstrations, farmer field school, farmer’s interest groups, field trips and farmer training programmes were moderately adopted. Posters, leaflets and pre-season campaigns were the widely adopted mass contact methods. They possess least skill in utilizing farm magazines, presenting television and radio programmes, which are among the most popular and most efficient mass contact methods. The extension functionaries need to be trained adequately on the wider use of electronic communication methods like e mails, and SMS in the local language. Efforts should be taken up to sensitize the importance and train the extension agents in the usage of different group and mass contact methods.

  20. Turning an Extension Aide into an Extension Agent

    Science.gov (United States)

    Seevers, Brenda; Dormody, Thomas J.

    2010-01-01

    For any organization to remain sustainable, a renewable source of faculty and staff needs to be available. The Extension Internship Program for Juniors and Seniors in High School is a new tool for recruiting and developing new Extension agents. Students get "hands on" experience working in an Extension office and earn college credit…

  1. Relatively hyperbolic extensions of groups and Cannon–Thurston ...

    Indian Academy of Sciences (India)

    In [6], the existence of a Cannon–Thurston map for the embedding i: K → G was proved, where K and G are respectively the Cayley graphs of K and G. In this paper, we will generalize these results to the case where the kernel is strongly hyperbolic relative to a cusp subgroup. One of our main theorems states: Theorem 2.10 ...

  2. Saipa Group, Iran - using strategic brand extensions to build relationships

    DEFF Research Database (Denmark)

    Hollensen, Svend; Wilson, Jonathan

    2010-01-01

    The purpose of the article is to provide insight into how branding is used in an innovative manner, when looking to generate brand equity and strengthen stakeholder relations - by a global car manufacturing company, governed by Iranian Islamic law. Following this, suggested areas of discussion...

  3. Spacetime extensions II

    Energy Technology Data Exchange (ETDEWEB)

    Racz, Istvan, E-mail: iracz@rmki.kfki.h [RMKI, H-1121 Budapest, Konkoly Thege Miklos ut 29-33 (Hungary)

    2010-08-07

    The global extendibility of smooth causal geodesically incomplete spacetimes is investigated. Denote by {gamma} one of the incomplete non-extendible causal geodesics of a causal geodesically incomplete spacetime (M, g{sub ab}). First, it is shown that it is always possible to select a synchronized family of causal geodesics {Gamma} and an open neighbourhood U of a final segment of {gamma} in M such that U comprises members of {Gamma}, and suitable local coordinates can be defined everywhere on U provided that {gamma} does not terminate either on a tidal force tensor singularity or on a topological singularity. It is also shown that if, in addition, the spacetime (M, g{sub ab}) is globally hyperbolic, and the components of the curvature tensor, and its covariant derivatives up to order k - 1 are bounded on U, and also the line integrals of the components of the kth-order covariant derivatives are finite along the members of {Gamma}-where all the components are meant to be registered with respect to a synchronized frame field on U-then there exists a C{sup k-} extension {Phi} : (M,g{sub ab}) {yields}(M,g{sub ab}) so that for each {gamma}-bar from {Gamma}, which is inextendible in (M, g{sub ab}), the image, {Phi}{gamma}-bar, is extendible in (M,g{sub ab}). Finally, it is also proved that whenever {gamma} does terminate on a topological singularity (M, g{sub ab}) cannot be generic.

  4. Web Extensible Display Manager

    Energy Technology Data Exchange (ETDEWEB)

    Slominski, Ryan [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Larrieu, Theodore L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2018-02-01

    Jefferson Lab's Web Extensible Display Manager (WEDM) allows staff to access EDM control system screens from a web browser in remote offices and from mobile devices. Native browser technologies are leveraged to avoid installing and managing software on remote clients such as browser plugins, tunnel applications, or an EDM environment. Since standard network ports are used firewall exceptions are minimized. To avoid security concerns from remote users modifying a control system, WEDM exposes read-only access and basic web authentication can be used to further restrict access. Updates of monitored EPICS channels are delivered via a Web Socket using a web gateway. The software translates EDM description files (denoted with the edl suffix) to HTML with Scalable Vector Graphics (SVG) following the EDM's edl file vector drawing rules to create faithful screen renderings. The WEDM server parses edl files and creates the HTML equivalent in real-time allowing existing screens to work without modification. Alternatively, the familiar drag and drop EDM screen creation tool can be used to create optimized screens sized specifically for smart phones and then rendered by WEDM.

  5. New polymer systems: Chain extension by dianhydrides

    Science.gov (United States)

    Rhein, R. A.; Ingham, J. D.

    1974-01-01

    Three anhydrides provide effective chain extension of hydroxy-terminated polyalkylene oxides and polybutadienes. Novel feature of these anhydride reactants is that they are difunctional as anhydrides, but they are tetrafunctional if conditions are selected that lead to total esterification or reaction of all carboxyl groups.

  6. Equivalence relations of AF-algebra extensions

    Indian Academy of Sciences (India)

    In this paper, we consider equivalence relations of *-algebra extensions and describe the relationship between the isomorphism equivalence and the unitary equivalence. We also show that a certain group homomorphism is the obstruction for these equivalence relations to be the same.

  7. Anionic water pentamer and hexamer clusters: An extensive study of structures and energetics

    Science.gov (United States)

    Ünal, Aslı; Bozkaya, Uǧur

    2018-03-01

    An extensive study of structures and energetics for anionic pentamer and hexamer clusters is performed employing high level ab initio quantum chemical methods, such as the density-fitted orbital-optimized linearized coupled-cluster doubles (DF-OLCCD), coupled-cluster singles and doubles (CCSD), and coupled-cluster singles and doubles with perturbative triples [CCSD(T)] methods. In this study, sixteen anionic pentamer clusters and eighteen anionic hexamer clusters are reported. Relative, binding, and vertical detachment energies (VDE) are presented at the complete basis set limit (CBS), extrapolating energies of aug4-cc-pVTZ and aug4-cc-pVQZ custom basis sets. The largest VDE values obtained at the CCSD(T)/CBS level are 9.9 and 11.2 kcal mol-1 for pentamers and hexamers, respectively, which are in very good agreement with the experimental values of 9.5 and 11.1 kcal mol-1. Our binding energy results, at the CCSD(T)/CBS level, indicate strong bindings in anionic clusters due to hydrogen bond interactions. The average binding energy per water molecules is -5.0 and -5.3 kcal mol-1 for pentamers and hexamers, respectively. Furthermore, our results demonstrate that the DF-OLCCD method approaches to the CCSD(T) quality for anionic clusters. The inexpensive analytic gradients of DF-OLCCD compared to CCSD or CCSD(T) make it very attractive for high-accuracy studies.

  8. Design extension conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bujor, A.; Harwood, C.; Lei, Q.; Viktorov, A., E-mail: christopher.harwood@cnsc-ccsn.gc.ca [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada)

    2013-07-01

    The CNSC has introduced the term Design Extension Conditions (DEC) in regulatory document RD-337 version 2, 'Design of New Nuclear Power Plants' which was issued for public consultation in July 2012. The primary drivers for this change compared with the earlier version of RD-337 are to maintain alignment with the equivalent International Atomic Energy Agency (IAEA) safety standard and to introduce changes resulting from lessons learned from the Fukushima Daiichi accident. RD-337 version 2 and the accompanying guidance document GD-337 establish high level design requirements and expectations for new Nuclear Power Plants (NPPs), including those pertaining to DEC. Other regulatory documents provide requirements for safety analysis and accident management as well as other aspect relevant to DEC. Nevertheless, the currently available guidance specific to DEC is not comprehensive, while the practices just begin to emerge. CNSC and industry stakeholders are actively discussing how the high level requirements and expectations will be applied in various fields. This paper is a summary of a CNSC discussion paper that is being developed to encourage substantive stakeholder discussions. The topic of DEC is being advanced rapidly both nationally and internationally. With this in mind, this paper does not intend to provide a final established position, but rather to stimulate discussion on the subject of DEC. This paper provides the definition of DEC, gives background information relating to the adoption of the term, describes the identification of DECs and the underlying principles associated with design, analysis, operational and procedural requirements. As described in this paper, DEC and associated requirements apply to new NPPs. Applicability to existing NPPs is also discussed. (author)

  9. A Classification of BPEL Extensions

    Directory of Open Access Journals (Sweden)

    Oliver Kopp

    2011-10-01

    Full Text Available The Business Process Execution Language (BPEL has emerged as de-facto standard for business processes implementation. This language is designed to be extensible for including additional valuable features in a standardized manner. There are a number of BPEL extensions available. They are, however, neither classified nor evaluated with respect to their compliance to the BPEL standard. This article fills this gap by providing a framework for classifying BPEL extensions, a classification of existing extensions, and a guideline for designing BPEL extensions.

  10. On Central Extensions of Associative Dialgebras

    Science.gov (United States)

    Rakhimov, Isamiddin S.

    2016-03-01

    The concept of central extensions plays an important in constructing extensions of algebras. This technique has been successfully used in the classification problem of certain classes of algebras. In 1978 Skjelbred and Sund reduced the classification of nilpotent Lie algebras in a given dimension to the study of orbits under the action of automorphism group on the space of second degree cohomology of a smaller Lie algebra with coefficients in a trivial module. Then W. de Graaf applied the Skjelbred and Sund method to the classification problem of low-dimensional nilpotent Lie and associative algebras over some fields. The main purpose of this note is to establish elementary properties of central extensions of associative dialgebras and apply the above mentioned method to the classification of low dimensional nilpotent associative dialgebras.

  11. On an extension of the Weil algebra

    International Nuclear Information System (INIS)

    Palev, Ch.

    An extension of the Weil algebra Wsub(n), generated by an appropriate topology is considered. The topology is introduced in such a way that algebraic operations in Wsub(n) to be continuous. The algebraic operations in Wsub(n) are extended by a natural way to a complement, which is noted as an extended Weil algebra. It turns out that the last algebra contains isomorphically the Heisenberg group. By the same way an arbitrary enveloping algebra of a Lie group may be extended. The extended algebra will contain the initial Lie group. (S.P.)

  12. Think - Baltic Extension / Kalle Kask

    Index Scriptorium Estoniae

    Kask, Kalle

    2002-01-01

    Tallinna TÜ Rehabilitatsiooni tehnoloogia keskus korraldas pressikonverentsi, kus tutvustati osalemist EL V raamprogrammis Think - Baltic Extension, mis on suunatud puuetega inimeste tööhõive tagamisele

  13. Robotic hand with modular extensions

    Science.gov (United States)

    Salisbury, Curt Michael; Quigley, Morgan

    2015-01-20

    A robotic device is described herein. The robotic device includes a frame that comprises a plurality of receiving regions that are configured to receive a respective plurality of modular robotic extensions. The modular robotic extensions are removably attachable to the frame at the respective receiving regions by way of respective mechanical fuses. Each mechanical fuse is configured to trip when a respective modular robotic extension experiences a predefined load condition, such that the respective modular robotic extension detaches from the frame when the load condition is met.

  14. Repeat Customer Success in Extension

    Science.gov (United States)

    Bess, Melissa M.; Traub, Sarah M.

    2013-01-01

    Four multi-session research-based programs were offered by two Extension specialist in one rural Missouri county. Eleven participants who came to multiple Extension programs could be called "repeat customers." Based on the total number of participants for all four programs, 25% could be deemed as repeat customers. Repeat customers had…

  15. Frames and extension problems I

    DEFF Research Database (Denmark)

    Christensen, Ole

    2014-01-01

    In this article we present a short survey of frame theory in Hilbert spaces. We discuss Gabor frames and wavelet frames and set the stage for a discussion of various extension principles; this will be presented in the article Frames and extension problems II (joint with H.O. Kim and R.Y. Kim)....

  16. Why Do Extension Agents Resign?

    Science.gov (United States)

    Manton, Linda Nunes; van Es, J. C.

    1985-01-01

    Past and current Illinois extension agents were surveyed via mail questionnaires as to reasons for staying or leaving extension programs. Reasons for leaving included family changes, family moves, opportunity to advance, better salary/benefits, dissatisfaction with administration, and too much time away from family. (CT)

  17. Universal extensions to simulate specifications

    NARCIS (Netherlands)

    Hesselink, Wim H.

    A previous paper introduced eternity variables as an alternative to the prophecy variables of Abadi and Lamport and proved the formalism to be semantically complete: every simulation F. K -> L that preserves quiescence contains a composition of a history extension, an extension with eternity

  18. Journal of Agricultural Extension submitted to Agricultural Extension ...

    African Journals Online (AJOL)

    PROF. MADUKWE

    ... typically confront narrower range of labour markets than men, and lower wage ... capabilities of women and by extension the household, female household ..... gap in accessibility to productive resources between male and female heads of.

  19. Advancing the Public Value Movement: Sustaining Extension during Tough Times

    Science.gov (United States)

    Franz, Nancy K.

    2011-01-01

    Extension must more fully and adeptly embrace the public value movement to be sustainable as a publicly funded organization, or our demise as an organization will continue. The public value steps outlined here and piloted with several Extension systems and national work groups can be informative for others interested in capturing and sharing the…

  20. Learning Joomla! 3 extension development

    CERN Document Server

    Plummer, Tim

    2013-01-01

    A practical guide with step-by-step examples that build on each other so you can learn by doing and get hands-on knowledge about creating your plugins, modules, and components in Joomla.""Learning Joomla! 3 Extension Development, Third Edition"" is for developers who want to create their own Joomla extensions. It is assumed you will have some basic PHP, HTML, and CSS knowledge, but you don't need any prior Joomla programming experience. This book will also be useful to people who just want to make minor customizations to existing Joomla extensions and build on the work of others in the open so

  1. Programming Reactive Extensions and LINQ

    CERN Document Server

    Liberty, Jesse

    2011-01-01

    Pro Reactive Extensions and LINQ is a deep dive into the next important technology for .NET developers: Reactive Extensions. This in-depth tutorial goes beyond what is available anywhere else to teach how to write WPF, Silverlight, and Windows Phone applications using the Reactive Extensions (Rx) to handle events and asynchronous method calls. Reactive programming allows you to turn those aspects of your code that are currently imperative into something much more event-driven and flexible. For this reason, it's sometimes referred to as LINQ for Events. Reactive programming hinges on the concep

  2. Extensions of the Standard Model

    CERN Document Server

    Zwirner, Fabio

    1996-01-01

    Rapporteur talk at the International Europhysics Conference on High Energy Physics, Brussels (Belgium), July 27-August 2, 1995. This talk begins with a brief general introduction to the extensions of the Standard Model, reviewing the ideology of effective field theories and its practical implications. The central part deals with candidate extensions near the Fermi scale, focusing on some phenomenological aspects of the Minimal Supersymmetric Standard Model. The final part discusses some possible low-energy implications of further extensions near the Planck scale, namely superstring theories.

  3. Characteristics and Motivational Factors of Effective Extension Advisory Leaders: Implications for Building Strong Extension Advisory Councils

    Directory of Open Access Journals (Sweden)

    Joy Kish

    2014-10-01

    Full Text Available The purpose of this study was to determine the characteristics and motivational factors of effective Extension advisory leaders. This Delphi study was conducted with a selected group of County Extension Directors and a group of Extension State Advisory Leaders. The study identified 10 characteristics that distinguish an effective Extension advisory leader. Some of these characteristics are explicit and easy to observe, while others are implicit and difficult to directly observe. Therefore, it is practical to use directly observable characteristics of effective advisory leaders when selecting volunteers. Once potential volunteers are spotted in the community, implicit characteristics of effective advisory leaders should be used to further screen them before they are selected. The study also identified the eight most important factors motivating individuals to volunteer as effective advisory leaders. Understanding these motivational factors is helpful for creating an environment for attracting and retaining effective volunteers. Understanding their motivation for volunteer work and creating an environment for them to meet the motivating factors for volunteering will lead to volunteer satisfaction and retention. The findings of this study can be used to build strong Extension advisory councils.

  4. Research-extension-farmer linkages

    African Journals Online (AJOL)

    agricultural research and extension services, Government in 1990 set up a number of ... charged with the role of articulating the most appropriate research and ... production of 1800 copies of NARO bulletin, 1000 copies of Uganda Journal of ...

  5. Journal of Environmental Extension: Submissions

    African Journals Online (AJOL)

    Journal of Environmental Extension is purely academic and accepts positional or ... and so responsibility for the content and macro formatting remain of the author. ... For research articles, the methodology, result analysis (statistical tests to be ...

  6. Boiler-turbine life extension

    Energy Technology Data Exchange (ETDEWEB)

    Natzkov, S. [TOTEMA, Ltd., Sofia (Bulgaria); Nikolov, M. [CERB, Sofia (Bulgaria)

    1995-12-01

    The design life of the main power equipment-boilers and turbines is about 105 working hours. The possibilities for life extension are after normatively regulated control tests. The diagnostics and methodology for Boilers and Turbines Elements Remaining Life Assessment using up to date computer programs, destructive and nondestructive control of metal of key elements of units equipment, metal creep and low cycle fatigue calculations. As well as data for most common damages and some technical decisions for elements life extension are presented.

  7. Towards effective extension delivery approach and strategies for ...

    African Journals Online (AJOL)

    Towards effective extension delivery approach and strategies for food security poverty ... Journal Home > Vol 6, No 1 (2010) > ... groups, promotion of best practices and environment friendly initiatives among others were recommended.

  8. Farmers and Extension Personnel View of Constraints to Effective ...

    African Journals Online (AJOL)

    E M IGBOKWE

    effectiveness of agricultural extension services in Oyo State, Nigeria. ... of farmers but include assisting farmer to form groups, dealing with marketing issues, ... traditional methods of farming system and animal husbandry practice, hence.

  9. Graev metrics on free products and HNN extensions

    DEFF Research Database (Denmark)

    Slutsky, Konstantin

    2014-01-01

    We give a construction of two-sided invariant metrics on free products (possibly with amalgamation) of groups with two-sided invariant metrics and, under certain conditions, on HNN extensions of such groups. Our approach is similar to the Graev's construction of metrics on free groups over pointed...

  10. The effects of sleep extension on sleep and cognitive performance in adolescents with chronic sleep reduction: an experimental study

    NARCIS (Netherlands)

    Dewald-Kaufmann, J.F.; Oort, F.J.; Meijer, A.M.

    2013-01-01

    Objective: To investigate the effects of gradual sleep extension in adolescents with chronic sleep reduction. Outcome variables were objectively measured sleep and cognitive performance. Methods: Participants were randomly assigned to either a sleep extension group (gradual sleep extension by

  11. Agricultural extension and mass media.

    Science.gov (United States)

    Perraton, H

    1983-12-01

    To learn more about the use of the mass media for agricultural extension, the World Bank has considered the efforts of 2 units: INADES-formation in West Africa and the Extension Aids Branch of Malawi. The INADES-formation study focuses on Cameroon but also considers work in Rwanda and the Ivory Coast. Some general conclusions emerge from a comparison of the 2 organizations. Malawi operates an extension service which reaches farmers through extension agents, through farmer training centers, and through mass media. The Extension Aids Branch (EAB) has responsibility for its media work and broadcasts 4 1/2 hours of radio each week. Its 6 regular radio programs include a general program which interviews farmers, a music request program in which the music is interspersed with farming advice, a farming family serial, and a daily broadcast of agricultural news and information. The 17 cinema vans show some agricultural films, made by EAB, some entertainment films, and some government information films from departments other than the ministry of agriculture. EAB also has a well-developed program of research and evaluation of its own work. INADES-formation, the training section of INADES, works towards social and economic development of the population. It teaches peasant farmers and extension agents and does this through running face-to-face seminars, by publishing a magazine, "Agripromo," and through correspondence courses. In 1978-79 INADES-formation enrolled some 4500 farmers and extension agents as students. Both of these organizations work to teach farmers better agriculture techniques, and both were created in response to the fact that agricultural extension agents cannot meet all the farmers in their area. Despite the similarity of objective, there are differences in methods and philosophy. The EAB works in a single country and uses a variety of mass media, with print playing a minor role. INADES-formation is an international and nongovernmental organization and its

  12. EXTENSION EDUCATION SYMPOSIUM: Getting the most out of your extension appointment and still having a life.

    Science.gov (United States)

    Powers, W; Cockett, N; Lardy, G

    2017-04-01

    Managing the demands of an academic appointment in extension can be a challenging task. Demands from constituent groups, expectations of supervisors, and rigors of promotion and tenure processes can create pressures that young faculty did not expect. Throw in spousal and family duties and you have created a situation that many will find hard to navigate. However, there are ways to cope and, even better news, there are ways to excel in meeting the demands of an academic appointment and enjoying life. Because many new extension faculty members do not have prior experience in extension, best practices in documenting programs and extension scholarship over the pretenure period are provided in this paper. Appointments that include both research and extension are quite common at many land grant universities. The advantages of joint appointments are numerous and include the fact that more and more grant agencies are seeking integrated research, teaching, and/or extension projects. However, the time demands of joint appointments can be challenging. Joint appointments can be designed to help faculty members conduct important translational research and have it be applied in a production setting. By seeking commonalities in research and extension efforts, joint appointments can be very synergistic. Development of highly successful programs requires planning on the front end with an emphasis on an in-depth needs assessment to determine stakeholder needs for both research and extension. Impact assessment should be part of this planning effort. Performing as a successful extension faculty member while maintaining relationships outside of work is challenging and requires deliberate effort on the part of employees and supervisors to realize there is more to life than work. Some authors have referred to this as work-life balance, but it may be more helpful to think of it as work-life effectiveness. To do this, one needs to 1) define what success looks like, 2) set boundaries and

  13. RURAL EXTENSION EPISTEMOLOGY AND THE TIME OF TOTAL EXTENSION

    Directory of Open Access Journals (Sweden)

    Silvio Calgaro Neto

    2016-09-01

    Full Text Available This article is dedicated to explore the field of knowledge related to rural extension. In general, a three complementary perspective is used as theoretical strategy to present this epistemological study. The first perspective, seeks to accomplish a brief archeology of rural extension, identifying the remarkable historical passages. At the second, we look to some theoretical models through the modern epistemological platform. Finally, the third perspective, aims to present a methodological proposal that contemplate this epistemic characteristics, relating with the contemporary transformations observed in the knowledge construction and technological transference for a rural development. Keywords: Total institutions. University.

  14. Lattices in group manifolds

    International Nuclear Information System (INIS)

    Lisboa, P.; Michael, C.

    1982-01-01

    We address the question of designing optimum discrete sets of points to represent numerically a continuous group manifold. We consider subsets which are extensions of the regular discrete subgroups. Applications to Monte Carlo simulation of SU(2) and SU(3) gauge theory are discussed. (orig.)

  15. Definable group extensions and o-minimal group cohomology via spectral sequences

    OpenAIRE

    Barriga, Eliana

    2013-01-01

    Se presenta el fundamento teórico para las sucesiones espectrales de Lyndon-Hochschild-Serre como una herramienta para estudiar la cohomología de grupos y con ésta las extensiones de grupos en la categoría de los grupos definibles. También se presentan varios resultados en módulos definibles y acciones, extensiones definibles y cohomología de grupos definibles. Estos tienen aplicaciones en el estudio de los grupos definibles no definiblemente compactos en teorías o-minimales (see [1]).

  16. Evaluation of group theoretical characteristics using the symbolic manipulation language MAPLE

    International Nuclear Information System (INIS)

    Taneri, U.; Paldus, J.

    1994-01-01

    Relying on theoretical developments exploiting quasispin and the pseudo-orthogonal group in the Hubbard model of cyclic polyenes, the general expressions for generating polynomials, providing the dimensional information for relevant irreducible representations, were derived. These generating polynomials result from 1-dimensional formulas through rather tedious algebraic manipulations involving ratios of polynomials with fractional powers. It is shown that these expressions may be efficiently handled using the symbolic manipulation language MAPLE and the dimensional information for an arbitrary spin, isospin, and quasimomentum obtained. Exploitation of symbolic computation for other group theoretical problems that are relevant in quantum chemical calculations and their relationship with Guassian polynomial based combinatorial approaches is also briefly addressed and various possible applications outlined

  17. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  18. Predicting group of metabolites available in partially purified tomato ...

    African Journals Online (AJOL)

    GREGORY

    2011-12-16

    Dec 16, 2011 ... Faculty of Engineering, International Islamic University Malaysia, Gombak, 50728 Kuala Lumpur, ... research had applied HPLC to identify and quantify the ..... energies of organic molecules with quantum chemical methods. J.

  19. verbal extensions: valency decreasing extensions in the basà ...

    African Journals Online (AJOL)

    Finance

    London: Hodder. Education. Imoh, P.M., 2013. Verbal extensions: Valency increasing operations in Basà verbal system. Paper presented at the West African Languages Congress (WALC) and 26th Annual. Conference of the Linguistic Association of Nigeria (26th CLAN), 29th July to 2nd August. 2013, University of Ibadan, ...

  20. Is boundary extension emotionally selective?

    Science.gov (United States)

    Ménétrier, Emmanuelle; Didierjean, André; Vieillard, Sandrine

    2013-01-01

    When they have to memorize a picture, people usually build a memory trace including more extensive boundaries than the original picture, a phenomenon known as boundary extension or BE. This article looks at whether the emotion category expressed (i.e., happiness, pleasure, irritation, or anger) by actors in short films could have an influence on the BE effect. The results showed that positively valenced emotions (happiness, pleasure) led to an extension effect, while the negatively valenced ones (anger, irritation) did not produce any significant memory distortion. The arousal dimension of emotions had no significant effect on BE. The current results were discussed in the light of previous studies on the links between BE and emotions.

  1. NDE and plant life extension

    International Nuclear Information System (INIS)

    Liu, S.N.; Ammirato, F.V.; Nottingham, L.D.

    1991-01-01

    Component life extension is the process of making run-repair-replace decisions for plant components and includes a thorough analysis of the capability of the component to perform throughout the projected lifetime. For many critical plant components, nondestructive evaluation (NDE) is essential in determining whether the component can be operated safely and economically in the extended life period and to help utilities determine safe and economic inspection intervals. NDE technology is required for not only detecting defects that could grow to a size of concern during extended lifetimes, but also will be called upon to measure and monitor accumulating material degradation that strongly affects component reliability. This paper discusses the role of NDE in life extension by reviewing three examples--a reactor pressure vessel, steam turbine-generator rotors, and generator retaining rings. In each example, the contribution of NDE to life extension decisions is described. (author)

  2. Elbow arthroscopy: valgus extension overload.

    Science.gov (United States)

    Ahmad, Christopher S; Conway, John E

    2011-01-01

    Valgus torque combined with deceleration produces high compression and shear forces acting on the posteromedial olecranon and the posteromedial trochlea. This valgus extension overload process may cause posteromedial trochlea chondromalacia, chondral flap formation, osteochondrosis, subchondral erosion, a subchondral insufficiency fracture, and marginal exostosis formation. Olecranon pathologies include proximal stress reaction, a posteromedial tip stress fracture, a transverse proximal process stress fracture, exostosis formation, exostosis fragmentation, and intra-articular loose bodies. Symptoms include posteromedial elbow pain during the deceleration phase of the throwing motion. The extension impingement test reproduces posterior or posteromedial pain similar to that experienced while throwing. Special radiographic techniques and CT scans can show loose bodies and osteophyte fragmentation. Surgical treatment is indicated when symptoms persist despite nonsurgical management. Based on clinical and basic science research, all patients with valgus extension overload should be comprehensively evaluated for medial ulnar collateral ligament insufficiency. Surgical treatment is limited to the resection of osteophytes only; normal olecranon should not be resected.

  3. Zinc Porphyrins Possessing Three p-Carboxyphenyl Groups: Effect of the Donor Strength of Push-Groups on the Efficiency of Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Ram B. Ambre

    2016-06-01

    Full Text Available Zinc porphyrins decorated with three p-carboxyphenyl anchoring groups and various “push” substituents of varied electron-donating strengths were prepared in good yields by facile and straightforward ways. The effect of electron-donating strength of the donor molecules on the overall power conversion efficiency was evaluated with the help of photophysical, electrochemical, photovoltaic spectroscopy and quantum chemical calculations. It is observed from the photophysical and Infrared (IR spectroscopic data that multi-anchoring dyes are more stable and bind more strongly to the TiO2 surface than their one-anchor counterparts. The properties like a three-step synthesis, high overall yields, possible mass production on a gram-scale and strong binding affinities with TiO2 surfaces make them a suitable choice for commercial applications. Zn1NH3A, with electron donating and anti-aggregation characteristics, achieved the highest efficiency of 6.50%.

  4. On extensions of superconformal algebras

    International Nuclear Information System (INIS)

    Nagi, Jasbir

    2005-01-01

    Starting from vector fields that preserve a differential form on a Riemann sphere with Grassmann variables, one can construct a superconformal algebra by considering central extensions of the algebra of vector fields. In this paper, the N=4 case is analyzed closely, where the presence of weight zero operators in the field theory forces the introduction of noncentral extensions. How this modifies the existing field theory, representation theory, and Gelfand-Fuchs constructions is discussed. It is also discussed how graded Riemann sphere geometry can be used to give a geometrical description of the central charge in the N=1 theory

  5. Structure-dependent tuning of electro-optic and thermoplastic properties in triphenyl groups containing molecular glasses

    Energy Technology Data Exchange (ETDEWEB)

    Traskovskis, Kaspars, E-mail: kaspars.traskovskis@rtu.lv [Riga Technical University, Faculty of Materials Science and Applied Chemistry, 3/7 Paula Valdena Street, Riga LV-1048 (Latvia); Zarins, Elmars; Laipniece, Lauma [Riga Technical University, Faculty of Materials Science and Applied Chemistry, 3/7 Paula Valdena Street, Riga LV-1048 (Latvia); Tokmakovs, Andrejs [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, Riga LV-1063 (Latvia); Kokars, Valdis [Riga Technical University, Faculty of Materials Science and Applied Chemistry, 3/7 Paula Valdena Street, Riga LV-1048 (Latvia); Rutkis, Martins [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, Riga LV-1063 (Latvia)

    2015-04-01

    The series of seven molecular compounds composed of D–π–A chromophores and triphenylmethyl auxiliary groups were characterized by UV–Vis spectroscopy, differential scanning calorimetry and quantum chemical calculations. Nonlinear optical (NLO) properties of compounds were determined by second harmonic generation measurements in corona poled thin glassy films. The results show that triphenylmethyl auxiliary groups are effective at shielding undesirable dipole interactions in solid phase thus increasing NLO efficiency of materials. Thermal stability up to 108 °C was achieved for a polar order in poled samples. - Highlights: • Triphenylmethyl groups can be used to reduce solid phase dipole interactions in organic molecular materials. • NLO efficiency of a poled material is higher, if a number of present triphenyl groups increases. • NLO efficiency of materials decreases, if polarity of used chromophores increases. • Thermal stability of polar order up to 108 °C can be achieved in poled organic glasses.

  6. On root class residuality of HNN-extensions

    International Nuclear Information System (INIS)

    Tieudjo, D.

    2004-08-01

    A sufficient condition or root-class residuality of HNN-extensions with root-class residual base group is proven; namely if G = -1 1Ht = K, φ> is the HNN-extension with base group A, stable letter t and associated subgroups H and K via the isomorphism φ, then G is root-class residual if group A is root-class residual and there exists a homomorphism σ of group G onto some group of a root-class such that σ is one-to-one on H. For the particular case when H = K and σ is the identical map, it is shown that G is root-class residual if and only if A is root-class residual and subgroup H of A is root-class separable. These results are generalized to multiple HNN-extensions. (author)

  7. Climate change and group dynamics

    NARCIS (Netherlands)

    Postmes, Tom

    2015-01-01

    The characteristics and views of people sceptical about climate change have been analysed extensively. A study now confirms that sceptics in the US have some characteristics of a social movement, but shows that the same group dynamics propel believers

  8. African Journal of Livestock Extension

    African Journals Online (AJOL)

    African Journal of Livestock Extension aims to bring to the fore the role and significance of livestock in maintaining rural, peri-urban and urban households, vis-à-vis its impact on poverty alleviation, household nutritional status, economic coping strategy and provision of employment. The focus of the journal relates to all ...

  9. Extensiveness of Farmers' Buying Process

    NARCIS (Netherlands)

    Kool, M.; Meulenberg, M.T.G.; Broens, D.F.

    1997-01-01

    In this article we study farmers' buying processes, in particular the selection of a supplier for a given farm input. Extensiveness of farmers' buying processes is defined as the degree information acquisition and alternative evaluation effort carried out to prepare that selection. Hypotheses,

  10. Cross System Extensions (CSE) experience

    International Nuclear Information System (INIS)

    Johnston, T.Y.

    1990-08-01

    Cross System Extension (CSE) provides VM/XA systems with the ability to share minidisks and spool in loosely coupled environment. CSE will also cooperate with the VM/HPO Inter System Facility (ISF) in sharing minidisks between VM/XA and VM/HPO to XA, reliability of CSE, and some operational considerations when running with it

  11. Extension Resources for International Trade

    Science.gov (United States)

    Seal, Susan D.

    2016-01-01

    With the opening of additional trade partnerships, the reduction of global transportation and communication costs, and the increase in demand for U.S. agricultural products and services, international trade is an area of great importance to more and more Extension clients and stakeholders. This article provides information about the primary…

  12. Agricultural Extension. A Reference Manual.

    Science.gov (United States)

    Maunder, Addison, H.

    The basic philosophy of agricultural extension was established in the more highly developed countries over the past century. Newly formed nations, the rural population of which formerly maintained a subsistence agriculture with limited industry, found it essential to establish a better-balanced economy. This led to a variety of rural services and…

  13. An extension of Babinet's principle

    International Nuclear Information System (INIS)

    da Silveira, R.

    1990-07-01

    It is shown that the diffraction pattern produced by any of two complementary screens and the one produced by a slit having the shape of their boundary, oscillates in opposite phase. This extension of Babinet's principle is illustrated with examples from nuclear scattering and classical optics

  14. Extension properties of states on operator algebras

    Science.gov (United States)

    Hamhalter, Jan

    1995-08-01

    We summarize and deepen some recent results concerning the extension problem for states on operator algebras and general quantum logics. In particular, we establish equivalence between the Gleason extension property, the Hahn-Banach extension property, and the universal state extension property of projection logics. Extensions of Jauch-Piron states are investigated.

  15. Diagram Techniques in Group Theory

    Science.gov (United States)

    Stedman, Geoffrey E.

    2009-09-01

    Preface; 1. Elementary examples; 2. Angular momentum coupling diagram techniques; 3. Extension to compact simple phase groups; 4. Symmetric and unitary groups; 5. Lie groups and Lie algebras; 6. Polarisation dependence of multiphoton processes; 7. Quantum field theoretic diagram techniques for atomic systems; 8. Applications; Appendix; References; Indexes.

  16. Extensive Focal Epithelial Hyperplasia: A Case Report.

    Science.gov (United States)

    Mansouri, Zahra; Bakhtiari, Sedigheh; Noormohamadi, Robab

    2015-01-01

    Focal epithelial hyperplasia (FEH) or Heck's disease is a rare viral infection of the oral mucosa caused by human papilloma virus especially subtypes 13 or 32. The frequency of this disease varies widely from one geographic region and ethnic groups to another. This paper reports an Iranian case of extensive focal epithelial hyperplasia. A 35-year-old man with FEH is described, in whom the lesions had persisted for more than 25 years. The lesion was diagnosed according to both clinical and histopathological features. Dental practitioner should be aware of these types of lesions and histopathological examination together and a careful clinical observation should be carried out for a definitive diagnosis.

  17. Extension Education Symposium: Getting the Most Out of Your Extension Appointment and Still Having a Life

    OpenAIRE

    Powers, W.; Cockett, Noelle E.; Lardy, Gregory P.

    2017-01-01

    Managing the demands of an academic appointment in extension can be a challenging task. Demands from constituent groups, expectations of supervisors, and rigors of promotion and tenure processes can create pressures that young faculty did not expect. Throw in spousal and family duties and you have created a situation that many will find hard to navigate. However, there are ways to cope and, even better news, there are ways to excel in meeting the demands of an academic appointment and enjoyin...

  18. Groupoid extensions of mapping class representations for bordered surfaces

    DEFF Research Database (Denmark)

    Andersen, Jørgen Ellegaard; Bene, Alex; Penner, Robert

    2009-01-01

    by explicit formulae depending upon six essential cases, and the kernel and image of the groupoid representation are computed. Furthermore, this provides groupoid extensions of any representation of the mapping class group that factors through its action on the fundamental group of the surface including...

  19. Participatory Contact Farmer Selection: Survey of two Extension ...

    African Journals Online (AJOL)

    This paper tested individual and group socio-metric nomination of potential contact farmers and compared the nominations with the CFs working in two extension circles. It was shown that only three (3) CFs out of eight (8) in the study appeared on both the individual and group nominations. It was recommended that EAs ...

  20. Curve collection, extension of databases

    International Nuclear Information System (INIS)

    Gillemot, F.

    1992-01-01

    Full text: Databases: generally calculated data only. The original measurements: diagrams. Information loss between them Expensive research eg. irradiation, aging, creep etc. Original curves should be stored for reanalysing. The format of the stored curves: a. Data in ASCII files, only numbers b. Other information in strings in a second file Same name, but different extension. Extensions shows the type of the test and the type of the file. EXAMPLES. TEN is tensile information, TED is tensile data, CHN is Charpy informations, CHD is Charpy data. Storing techniques: digitalised measurements, digitalising old curves stored on paper. Use: making catalogues, reanalysing, comparison with new data. Tools: mathematical software packages like quattro, genplot, exel, mathcad, qbasic, pascal, fortran, mathlab, grapher etc. (author)

  1. New examples of frobenius extensions

    CERN Document Server

    Kadison, Lars

    1999-01-01

    This volume is based on the author's lecture courses to algebraists at Munich and at G�teborg. He presents, for the first time in book form, a unified approach from the point of view of Frobenius algebras/extensions to diverse topics, such as Jones' subfactor theory, Hopf algebras and Hopf subalgebras, the Yang-Baxter Equation and 2-dimensional topological quantum field theories. Other Features: Initial steps toward a theory of noncommutative ring extensions. Self-contained sections on Azumaya algebras and strongly separable algebras. Applications and generalizations of Morita theory and Azumaya algebra due to Hirata and Sugano. Understanding the text requires no prior background in Frobenius algebras or Hopf algebras. An index and a thorough list of further references are included. There is an appendix giving a brief historical guide to the literature.

  2. Linear programming foundations and extensions

    CERN Document Server

    Vanderbei, Robert J

    2001-01-01

    Linear Programming: Foundations and Extensions is an introduction to the field of optimization. The book emphasizes constrained optimization, beginning with a substantial treatment of linear programming, and proceeding to convex analysis, network flows, integer programming, quadratic programming, and convex optimization. The book is carefully written. Specific examples and concrete algorithms precede more abstract topics. Topics are clearly developed with a large number of numerical examples worked out in detail. Moreover, Linear Programming: Foundations and Extensions underscores the purpose of optimization: to solve practical problems on a computer. Accordingly, the book is coordinated with free efficient C programs that implement the major algorithms studied: -The two-phase simplex method; -The primal-dual simplex method; -The path-following interior-point method; -The homogeneous self-dual methods. In addition, there are online JAVA applets that illustrate various pivot rules and variants of the simplex m...

  3. Managing BWR plant life extension

    International Nuclear Information System (INIS)

    Ianni, P.W.; Kiss, E.

    1985-01-01

    Recent studies have confirmed that extending the useful life of a large nuclear plant can be justified with very high cost benefit ratio. In turn, experience with large power plant systems and equipment has shown that a well-integrated and -managed plan is essential in order to achieve potential economic benefits. Consequently, General Electric's efforts have been directed at establishing a life extension plan that considers alternative options and cost-effective steps that can be taken in early life, those appropriate during middle life, and those required in late life. This paper briefly describes an approach designed to provide the plant owner a maximum of flexibility in developing a life extension plan

  4. Perineural extension of facial melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Kalina, Peter [Mayo Clinic, Department of Radiology, Rochester, Minnesota (United States); Bevilacqua, Paula

    2005-05-01

    A 64-year-old man presented with a pigmented cutaneous lesion on the right side of his face along with right facial numbness. Histological examination revealed malignant melanoma. Magnetic resonance imaging (MRI) revealed perineural extension along the entire course of the maxillary division of the right trigeminal nerve. This is a rare but important manifestation of the spread of head and neck malignancy. (orig.)

  5. Recall in extensive form games

    OpenAIRE

    Klaus Ritzberger

    1999-01-01

    This paper considers characterizations of perfect recall in extensive form games. It is shown that perfect recall can be expressed in terms of choices without any reference to infomation sets. When information sets are taken into account, it is decomposable into an ordering of information sets and that players do not forget what they knew nor what they did. Thus, if information sets are partially ordered, then perfect recall is implied by the player's inability to refine her information from ...

  6. Dosimetry of β extensive sources

    International Nuclear Information System (INIS)

    Rojas C, E.L.; Lallena R, A.M.

    2002-01-01

    In this work, we have been studied, making use of the Penelope Monte Carlo simulation code, the dosimetry of β extensive sources in situations of spherical geometry including interfaces. These configurations are of interest in the treatment of the called cranealfaringyomes of some synovia leisure of knee and other problems of interest in medical physics. Therefore, its application can be extended toward problems of another areas with similar geometric situation and beta sources. (Author)

  7. Conformal Extensions of the Standard Model with Veltman Conditions

    DEFF Research Database (Denmark)

    Antipin, Oleg; Mojaza, Matin; Sannino, Francesco

    2014-01-01

    Using the renormalisation group framework we classify different extensions of the standard model according to their degree of naturality. A new relevant class of perturbative models involving elementary scalars is the one in which the theory simultaneously satisfies the Veltman conditions...... and is conformal at the classical level. We term these extensions perturbative natural conformal (PNC) theories. We show that PNC models are very constrained and thus highly predictive. Among the several PNC examples that we exhibit, we discover a remarkably simple PNC extension of the standard model in which...

  8. Evaluation of group electronegativities and hardness (softness) of group 14 elements and containing functional groups through density functional theory and correlation with NMR spectra data

    International Nuclear Information System (INIS)

    Vivas-Reyes, R.; Aria, A.

    2008-01-01

    Quantum Chemical calculations for group 14 elements of Periodic Table (C, Si, Ge, Sn, Pb) and their functional groups have been carried out using Density Functional Theory (DFT) based reactivity descriptors such as group electronegativities, hardness and softness. DFT calculations were performed for a large series of tetra coordinated Sn compounds of the CH 3 SnRR'X type, where X is a halogen and R and R' are alkyl, halogenated alkyl, alkoxy, or alkyl thio groups. The results were interpreted in terms of calculated electronegativity and hardness of the SnRR'X groups, applying a methodology previously developed by Geerlings and coworkers (J. Phys. Chem. 1993, 97, 1826). These calculations allowed to see the regularities concerning the influence of the nature of organic groups RR' and inorganic group X on electronegativities and hardness of the SnRR'X groups; in this case, it was found a very good correlation between the electronegativity of the fragment and experimental 119 Sn chemical shifts, a property that sensitively reflects the change in the valence electronic structure of molecules. This work was complemented with the study of some compounds of the EX and ER types, where E= C, Si, Ge, Sn and R= CH 3 , H, which was performed to study the influence that the central atom has on the electronegativity and hardness of molecules, or whether these properties are mainly affected for the type of ligand bound to the central atom. All these calculations were performed using the B3PW91 functional together with the 6-3 1 1 + + G basis set level for H, C, Si, Ge, F, Cl and Br atoms and the 3-21G for Sn and I atoms. (author)

  9. Evaluation of group electronegativities and hardness (softness) of group 14 elements and containing functional groups through density functional theory and correlation with NMR spectra data

    Energy Technology Data Exchange (ETDEWEB)

    Vivas-Reyes, R.; Aria, A. [Universidad de Cartagena, Cartagena (Colombia). Facultad de Ciencias Naturales y Exactas. Grupo de Quimica Cuantica y Computacional]. E-mail: rvivasr@unicartagena.edu.co

    2008-07-01

    Quantum Chemical calculations for group 14 elements of Periodic Table (C, Si, Ge, Sn, Pb) and their functional groups have been carried out using Density Functional Theory (DFT) based reactivity descriptors such as group electronegativities, hardness and softness. DFT calculations were performed for a large series of tetra coordinated Sn compounds of the CH{sub 3}SnRR'X type, where X is a halogen and R and R' are alkyl, halogenated alkyl, alkoxy, or alkyl thio groups. The results were interpreted in terms of calculated electronegativity and hardness of the SnRR'X groups, applying a methodology previously developed by Geerlings and coworkers (J. Phys. Chem. 1993, 97, 1826). These calculations allowed to see the regularities concerning the influence of the nature of organic groups RR' and inorganic group X on electronegativities and hardness of the SnRR'X groups; in this case, it was found a very good correlation between the electronegativity of the fragment and experimental {sup 119}Sn chemical shifts, a property that sensitively reflects the change in the valence electronic structure of molecules. This work was complemented with the study of some compounds of the EX and ER types, where E= C, Si, Ge, Sn and R= CH{sub 3}, H, which was performed to study the influence that the central atom has on the electronegativity and hardness of molecules, or whether these properties are mainly affected for the type of ligand bound to the central atom. All these calculations were performed using the B3PW91 functional together with the 6-3 1 1 + + G basis set level for H, C, Si, Ge, F, Cl and Br atoms and the 3-21G for Sn and I atoms. (author)

  10. Group X

    Energy Technology Data Exchange (ETDEWEB)

    Fields, Susannah

    2007-08-16

    This project is currently under contract for research through the Department of Homeland Security until 2011. The group I was responsible for studying has to remain confidential so as not to affect the current project. All dates, reference links and authors, and other distinguishing characteristics of the original group have been removed from this report. All references to the name of this group or the individual splinter groups has been changed to 'Group X'. I have been collecting texts from a variety of sources intended for the use of recruiting and radicalizing members for Group X splinter groups for the purpose of researching the motivation and intent of leaders of those groups and their influence over the likelihood of group radicalization. This work included visiting many Group X websites to find information on splinter group leaders and finding their statements to new and old members. This proved difficult because the splinter groups of Group X are united in beliefs, but differ in public opinion. They are eager to tear each other down, prove their superiority, and yet remain anonymous. After a few weeks of intense searching, a list of eight recruiting texts and eight radicalizing texts from a variety of Group X leaders were compiled.

  11. Group Flow and Group Genius

    Science.gov (United States)

    Sawyer, Keith

    2015-01-01

    Keith Sawyer views the spontaneous collaboration of group creativity and improvisation actions as "group flow," which organizations can use to function at optimum levels. Sawyer establishes ideal conditions for group flow: group goals, close listening, complete concentration, being in control, blending egos, equal participation, knowing…

  12. Professional development and extension programs

    Energy Technology Data Exchange (ETDEWEB)

    Bereznai, G. [University of Ontario Institute of Technology, Oshawa, ON (Canada)

    2015-07-01

    Professional Development (PD) refers to the means by which people acquire, develop, maintain and enhance the specialist knowledge and skills needed to practice in their profession. Extension Programs (aka Continuing Education) are offered by most post-secondary degree/diploma/certificate granting institutions.The courses are typically taken on a part-time basis, and course delivery often includes distance learning technology. An important implementation of PD is via workplace training, industry specific seminars, workshops and non-credit courses offered by a wide range of service providers.

  13. Professional development and extension programs

    International Nuclear Information System (INIS)

    Bereznai, G.

    2015-01-01

    Professional Development (PD) refers to the means by which people acquire, develop, maintain and enhance the specialist knowledge and skills needed to practice in their profession. Extension Programs (aka Continuing Education) are offered by most post-secondary degree/diploma/certificate granting institutions.The courses are typically taken on a part-time basis, and course delivery often includes distance learning technology. An important implementation of PD is via workplace training, industry specific seminars, workshops and non-credit courses offered by a wide range of service providers.

  14. New Stethoscope With Extensible Diaphragm.

    Science.gov (United States)

    Takashina, Tsunekazu; Shimizu, Masashi; Muratake, Torakazu; Mayuzumi, Syuichi

    2016-08-25

    This study compared the diagnostic efficacy of the common suspended diaphragm stethoscope (SDS) with a new extensible diaphragm stethoscope (EDS) for low-frequency heart sounds. The EDS was developed by using an ethylene propylene diene monomer diaphragm. The results showed that the EDS enhanced both the volume and quality of low-frequency heart sounds, and improved the ability of examiners to auscultate such heart sounds. Based on the results of the sound analysis, the EDS is more efficient than the SDS. (Circ J 2016; 80: 2047-2049).

  15. Japanese plant life extension program

    International Nuclear Information System (INIS)

    Yoshitsugu, M.

    1988-01-01

    As one of the main items of up-grading light water reactor program in Japan, plant life extension has been recommended by Advisory Committee of Ministry of International trade and Industry and the practical work has begun to be carried out. It is overviewed here. After preliminary works, including investigation on the state of the arts through a entrusted survey work, participation in international meetings and exchange of informations with related organizations, actual work has just started. So-called critical components based on our experience during the past 17 years have been listed up and some experimental works inaugurated as from 1987

  16. Analyzing the natural resource extension needs of Spanish-speakers: A perspective from Florida

    Science.gov (United States)

    Miriam Wyman; Francisco Escobedo; Sebastian Varela; Cesar Asuaje; Henry Mayer; Mickie Swisher; Annie Hermansen

    2011-01-01

    Hispanics are the country's fastest growing minority group. The study reported here surveyed and assessed Extension agents from two demographically different regions in Florida on perceptions and attitudes about the need, quality, and dissemination of Spanish Extension materials. Results showed Extension programs are important sources of information for Spanish-...

  17. JESS: Java extensible snakes system

    Science.gov (United States)

    McInerney, Tim; Akhavan Sharif, M. Reza; Pashotanizadeh, Nasrin

    2005-04-01

    Snakes (Active Contour Models) are powerful model-based image segmentation tools. Although researchers have proven them especially useful in medical image analysis over the past decade, Snakes have remained primarily in the academic world and they have not become widely used in clinical practice or widely available in commercial packages. A number of confusing and specialized variants exist and there has been no standard open-source implementation available. To address this problem, we present a Java Extensible Snakes System (JESS) that is general, portable, and extensible. The system uses Java Swing classes to allow for the rapid development of custom graphical user interfaces (GUI's). It also incorporates the Java Advanced Imaging(JAI) class library, which provide custom image preprocessing, image display and general image I/O. The Snakes algorithm itself is written in a hierarchical fashion, consisting of a general Snake class and several subclasses that span the main variants of Snakes including a new, powerful, robust subdivision-curve Snake. These subclasses can be easily and quickly extended and customized for any specific segmentation and analysis task. We demonstrate the utility of these classes for segmenting various anatomical structures from 2D medical images. We also demonstrate the effectiveness of JESS by using it to rapidly build a prototype semi-automatic sperm analysis system. The JESS software will be made publicly available in early 2005.

  18. Bell, group and tangle

    International Nuclear Information System (INIS)

    Solomon, A. I.

    2010-01-01

    The 'Bell' of the title refers to bipartite Bell states, and their extensions to, for example, tripartite systems. The 'Group' of the title is the Braid Group in its various representations; while 'Tangle' refers to the property of entanglement which is present in both of these scenarios. The objective of this note is to explore the relation between Quantum Entanglement and Topological Links, and to show that the use of the language of entanglement in both cases is more than one of linguistic analogy.

  19. Experimental and quantum chemical simulations on the corrosion inhibition of mild steel by 3-((5-(3,5-dinitrophenyl)-1,3,4-thiadiazol-2-yl)imino)indolin-2-one

    Science.gov (United States)

    Al-Azawi, Khalida F.; Mohammed, Iman Mahdi; Al-Baghdadi, Shaimaa B.; Salman, Taghried A.; Issa, Hamsa A.; Al-Amiery, Ahmed A.; Gaaz, Tayser Sumer; Kadhum, Abdul Amir H.

    2018-06-01

    Iraq has been one of the most extensive oil and natural gas industries in the world. The corrosion of mild steel is costly and insufficiency process. It is responsible for great loss in manufacture and environment. Natural and organic inhibitors have been utilized for a long time to inhibit the corrosion. Selected thiadiazol derivative, namely 3-((5-(3,5-dinitrophenyl)-1,3,4-thiadiazol-2-yl)imino)indolin-2-one (TDIO) was investigated for it inhibitive impacts in 1 M HCl medium on corrosion of mild steel using weight loss and scanning electron microscope techniques. The maximum inhibition efficiency up to 90.7% at the maximum inhibitor concentration 0.5 mM. Surface morphology of results demonstrated that TDIO formed adsorbed film on surface of mild steel in hydrochloric acid solution. Give molecular based clarifications to the inhibitive impacts of the studied. The interactions between mild steel surface and the inhibitor molecules have been undertaken to further corroborate the methodological results.

  20. Residual nilpotence and residual solubility of groups

    International Nuclear Information System (INIS)

    Mikhailov, R V

    2005-01-01

    The properties of the residual nilpotence and the residual solubility of groups are studied. The main objects under investigation are the class of residually nilpotent groups such that each central extension of these groups is also residually nilpotent and the class of residually soluble groups such that each Abelian extension of these groups is residually soluble. Various examples of groups not belonging to these classes are constructed by homological methods and methods of the theory of modules over group rings. Several applications of the theory under consideration are presented and problems concerning the residual nilpotence of one-relator groups are considered.

  1. Group devaluation and group identification

    NARCIS (Netherlands)

    Leach, C.W.; Rodriguez Mosquera, P.M.; Vliek, M.L.W.; Hirt, E.

    2010-01-01

    In three studies, we showed that increased in-group identification after (perceived or actual) group devaluation is an assertion of a (preexisting) positive social identity that counters the negative social identity implied in societal devaluation. Two studies with real-world groups used order

  2. Lie groups and algebraic groups

    Indian Academy of Sciences (India)

    We give an exposition of certain topics in Lie groups and algebraic groups. This is not a complete ... of a polynomial equation is equivalent to the solva- bility of the equation ..... to a subgroup of the group of roots of unity in k (in particular, it is a ...

  3. Fluorescein-related extensive jaundice.

    Science.gov (United States)

    Kalkan, Asim; Turedi, Suleyman; Aydin, Ibrahim

    2015-03-01

    Fluorescein is a chemical dye frequently used in eye diseases to assess blood flow in the retina, choroid tissue, and iris. Although it has many known adverse effects, it has not previously been reported to lead to jaundice. The purpose of this case report was to emphasize that for patients presenting at the emergency department with jaundice symptoms, it should not be forgotten by emergency physicians that jaundice can develop after fluorescein angiography. Case: A 65-year-old woman presented at the emergency department with extensive jaundice that had developed on her entire body a few hours after fluorescein angiography applied because of vision impairment. The test results for all the diseases considered to cause jaundice were normal,and fluorescein-related jaundice was diagnosed. Conclusion: A detailed anamnesis should be taken when jaundice is seen in patients who have undergone fluorescein angiography, and it should not be forgotten that fluorescein dye is a rare cause of jaundice.

  4. An extension of fuzzy decisi

    Directory of Open Access Journals (Sweden)

    Basem Mohamed Elomda

    2013-07-01

    Full Text Available This paper presents a new extension to Fuzzy Decision Maps (FDMs by allowing use of fuzzy linguistic values to represent relative importance among criteria in the preference matrix as well as representing relative influence among criteria for computing the steady-state matrix in the stage of Fuzzy Cognitive Map (FCM. The proposed model is called the Linguistic Fuzzy Decision Networks (LFDNs. The proposed LFDN provides considerable flexibility to decision makers when solving real world Multi-Criteria Decision-Making (MCDM problems. The performance of the proposed LFDN model is compared with the original FDM using a previously published case study. The result of comparison ensures the ability to draw the same decisions with a more realistic decision environment.

  5. Extensible numerical library in JAVA

    International Nuclear Information System (INIS)

    Aso, T.; Okazawa, H.; Takashimizu, N.

    2001-01-01

    The authors present the current status of the project for developing the numerical library in JAVA. The authors have presented how object-oriented techniques improve usage and also development of numerical libraries compared with the conventional way at previous conference. The authors need many functions for data analysis which is not provided within JAVA language, for example, good random number generators, special functions and so on. Authors' development strategy is focused on easiness of implementation and adding new features by users themselves not only by developers. In HPC field, there are other focus efforts to develop numerical libraries in JAVA. However, their focus is on the performance of execution, not easiness of extension. Following the strategy, the authors have designed and implemented more classes for random number generators and so on

  6. Extensive Renovation of Heritage Buildings

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn; Møller, Eva B.; Buch-Hansen, Thomas Cornelius

    2015-01-01

    In the debate on whether or not heritage buildings should be included in work to mitigate climate change impacts, it is important to assess the impact of these buildings. Therefore the results of an extensive energy upgrading of a listed complex was studied. Climate change and measures to mitigate...... its effects have been a global priority for more than a decade. Efforts to mitigate climate change have focused on reducing greenhouse gas emissions, especially CO2. As a consequence, there is an increased interest in reducing the energy consumption and increase the indoor climate standard of many...... feasible energy-upgrading measures for implementation including measures to provide an acceptable indoor climate. The energy savings as well as the reduction of CO2 emissions are calculated. Furthermore, it is discussed how measures can affect the durability of a heritage building, as measures may create...

  7. Prognostic significance of surgical extranodal extension in head and neck squamous cell carcinoma patients.

    Science.gov (United States)

    Matsumoto, Fumihiko; Mori, Taisuke; Matsumura, Satoko; Matsumoto, Yoshifumi; Fukasawa, Masahiko; Teshima, Masanori; Kobayashi, Kenya; Yoshimoto, Seiichi

    2017-08-01

    Lymph node metastasis with extranodal extension represents one of the most important adverse prognostic factors for survival in patients with head and neck squamous cell carcinoma. We propose that extranodal extension occurs to differing extents. The aim of this study was to determine the prognostic significance of extranodal extension in patients with head and neck squamous cell carcinoma. Two hundred and ninety-eight patients with head and neck squamous cell carcinoma who underwent surgical resection and neck dissection were included. Cervical lymph nodes were classified into four categories: (i) pathological N negative, (ii) extranodal extension negative, (iii) non-surgical extranodal extension and (iv) surgical extranodal extension. Lymph node metastases were detected in 67.1% of laryngeal/hypopharyngeal cancer patients and 52.7% of oral cancer patients. The 3-year disease-specific survival rates for patients in the pathological N negative, extranodal extension negative, non-surgical extranodal extension and surgical extranodal extension groups were 90.9%, 79.6%, 63.8% and 48.3%, respectively. In laryngeal/hypopharyngeal cancer patients, surgical extranodal extension was associated with a significantly poorer disease-specific survival than a pathological N negative, extranodal extension negative or non-surgical extranodal extension status. In oral cancer patients, no significant differences were observed between the non-surgical and surgical extranodal extension groups. However, non-surgical extranodal extension was associated with a poorer disease-specific survival than a pathological N negative or extranodal extension negative status. Surgical extranodal extension was a poor prognostic factor in patients with head and neck squamous cell carcinoma. The prognostic significance of surgical extranodal extension differed between laryngeal/hypopharyngeal and oral cancer patients. The clinical significance of surgical extranodal extension was much greater for

  8. Competency Modeling in Extension Education: Integrating an Academic Extension Education Model with an Extension Human Resource Management Model

    Science.gov (United States)

    Scheer, Scott D.; Cochran, Graham R.; Harder, Amy; Place, Nick T.

    2011-01-01

    The purpose of this study was to compare and contrast an academic extension education model with an Extension human resource management model. The academic model of 19 competencies was similar across the 22 competencies of the Extension human resource management model. There were seven unique competencies for the human resource management model.…

  9. Knee extension torque variability after exercise in ACL reconstructed knees.

    Science.gov (United States)

    Goetschius, John; Kuenze, Christopher M; Hart, Joseph M

    2015-08-01

    The purpose of this study was to compare knee extension torque variability in patients with ACL reconstructed knees before and after exercise. Thirty two patients with an ACL reconstructed knee (ACL-R group) and 32 healthy controls (control group) completed measures of maximal isometric knee extension torque (90° flexion) at baseline and following a 30-min exercise protocol (post-exercise). Exercise included 30-min of repeated cycles of inclined treadmill walking and hopping tasks. Dependent variables were the coefficient of variation (CV) and raw-change in CV (ΔCV): CV = (torque standard deviation/torque mean x 100), ΔCV = (post-exercise - baseline). There was a group-by-time interaction (p = 0.03) on CV. The ACL-R group demonstrated greater CV than the control group at baseline (ACL-R = 1.07 ± 0.55, control = 0.79 ± 0.42, p = 0.03) and post-exercise (ACL-R = 1.60 ± 0.91, control = 0.94 ± 0.41, p = 0.001). ΔCV was greater (p = 0.03) in the ACL-R group (0.52 ± 0.82) than control group (0.15 ± 0.46). CV significantly increased from baseline to post-exercise (p = 0.001) in the ACL-R group, while the control group did not (p = 0.06). The ACL-R group demonstrated greater knee extension torque variability than the control group. Exercise increased torque variability more in the ACL-R group than control group. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  10. Reflection groups

    International Nuclear Information System (INIS)

    Eggermont, G.

    2006-01-01

    In 2005, PISA organised proactive meetings of reflection groups on involvement in decision making, expert culture and ethical aspects of radiation protection.All reflection group meetings address particular targeted audiences while the output publication in book form is put forward

  11. Strengthening Agricultural Research Capacity for Viable Extension ...

    African Journals Online (AJOL)

    Strengthening Agricultural Research Capacity for Viable Extension Policies in Nigeria: An Exploration of Ricoeur's Hermeneutic Theory for Analysing Extension Research. ... Progressively more, researchers use hermeneutic philosophy to inform the conduct of interpretive research. Analogy between the philosophical ...

  12. Field Extension by Galois Theory

    OpenAIRE

    Md Taufiq Nasseef

    2017-01-01

    Galois Theory, a wonderful part of mathematics with historical roots date back to the solution of cubic and quantic equations in the sixteenth century. However, beside understanding the roots of polynomials, Galois Theory also gave birth to many of the central concepts of modern algebra, including groups and fields. In particular, this theory is further great due to primarily for two factors: first, its surprising link between the group theory and the roots of polynomials and second,the eleganc...

  13. Logic regression and its extensions.

    Science.gov (United States)

    Schwender, Holger; Ruczinski, Ingo

    2010-01-01

    Logic regression is an adaptive classification and regression procedure, initially developed to reveal interacting single nucleotide polymorphisms (SNPs) in genetic association studies. In general, this approach can be used in any setting with binary predictors, when the interaction of these covariates is of primary interest. Logic regression searches for Boolean (logic) combinations of binary variables that best explain the variability in the outcome variable, and thus, reveals variables and interactions that are associated with the response and/or have predictive capabilities. The logic expressions are embedded in a generalized linear regression framework, and thus, logic regression can handle a variety of outcome types, such as binary responses in case-control studies, numeric responses, and time-to-event data. In this chapter, we provide an introduction to the logic regression methodology, list some applications in public health and medicine, and summarize some of the direct extensions and modifications of logic regression that have been proposed in the literature. Copyright © 2010 Elsevier Inc. All rights reserved.

  14. Presentation Extensions of the SOAP

    Science.gov (United States)

    Carnright, Robert; Stodden, David; Coggi, John

    2009-01-01

    A set of extensions of the Satellite Orbit Analysis Program (SOAP) enables simultaneous and/or sequential presentation of information from multiple sources. SOAP is used in the aerospace community as a means of collaborative visualization and analysis of data on planned spacecraft missions. The following definitions of terms also describe the display modalities of SOAP as now extended: In SOAP terminology, View signifies an animated three-dimensional (3D) scene, two-dimensional still image, plot of numerical data, or any other visible display derived from a computational simulation or other data source; a) "Viewport" signifies a rectangular portion of a computer-display window containing a view; b) "Palette" signifies a collection of one or more viewports configured for simultaneous (split-screen) display in the same window; c) "Slide" signifies a palette with a beginning and ending time and an animation time step; and d) "Presentation" signifies a prescribed sequence of slides. For example, multiple 3D views from different locations can be crafted for simultaneous display and combined with numerical plots and other representations of data for both qualitative and quantitative analysis. The resulting sets of views can be temporally sequenced to convey visual impressions of a sequence of events for a planned mission.

  15. XPL the Extensible Presentation Language

    Directory of Open Access Journals (Sweden)

    A. Santangelo

    2009-01-01

    Full Text Available The last decade has witnessed a growing interest in the development of web interfaces enabling both multiple ways to access contents and, at the same time, fruition by multiple modalities of interaction (point-and-click, contents reading, voice commands, gestures, etc.. In this paper we describe a framework aimed at streamlining the design process of multi-channel, multimodal interfaces enabling full reuse of software components. This framework is called the eXtensible Presentation architecture and Language (XPL, a presentation language based on design pattern paradigm that keeps separated the presentation layer from the underlying programming logic. The language supplies a methodology to expedite multimodal interface development and to reduce the effort to implement interfaces for multiple access devices, by means of using the same code. This paper describes a methodology approach based on Visual Design Pattern (ViDP and Verbal Design Pattern (VeDP, offering examples of multimodal and multichannel interfaces created with the XPL Editor.

  16. Effectiveness Of Communication Outreach Strategies Of Extension ...

    African Journals Online (AJOL)

    Communication is a major component of agricultural extension and extension agents utilize various methods to deliver messages to their clienteles. The paper focused on the effectiveness of communication outreach strategies of extension agents in Imo State, Nigeria. Data for the study was collected with the aid of ...

  17. Purdue Extension: Employee Engagement and Leadership Style

    Science.gov (United States)

    Abbott, Angela R.

    2017-01-01

    The purpose of this quantitative study was to assess the Purdue Extension county directors' level of engagement and leadership style and to examine the relationship between these two variables. The study aimed to inform a professional development training program for all Purdue Extension county extension directors. Survey data were collected from…

  18. Building and Managing Makerspaces in Extension

    Science.gov (United States)

    Francis, Dave; Hill, Paul; Graham, Dallini; Swadley, Emy; Esplin, Kaleb

    2017-01-01

    As traditional face-to-face Extension office interactions are supplanted by online education options, the makerspace offers a venue for authentic engagement between Extension and the community. In makerspaces, learners make and learn from one another in a cooperative learning environment. Through involvement in the maker movement, Extension has an…

  19. 7 CFR 15b.27 - Extension education.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Extension education. 15b.27 Section 15b.27 Agriculture... Education § 15b.27 Extension education. (a) General. A recipient to which this subpart applies that provides extension education may not, on the basis of handicap, exclude qualified handicapped persons. A recipient...

  20. User contributions and public extension delivery modes ...

    African Journals Online (AJOL)

    The high recurrent costs faced by the public extension service constraint the number of visits farmers receive. This study examined a number of extension communication channels through which farmers received farm management services/information from the public extension agent. The idea was, first, to find out the ...

  1. Improving Disability Awareness among Extension Agents

    Science.gov (United States)

    Mahadevan, Lakshmi; Peterson, Rick L.; Grenwelge, Cheryl

    2014-01-01

    Increasing prevalence rates and legislative mandates imply that educators, parents, and Extension agents will need better tools and resources to meet the needs of special populations. The Texas A&M AgriLife Extension Service addresses this issue by using e-learning tools. Extension agents can take advantage of these courses to gain critical…

  2. Gender analysis of use of participatory tools among extension workers

    African Journals Online (AJOL)

    (c2 = 0.833, p = 0.361; t = 0.737, p = 0.737, CC = 0.396) Participatory tools used by both male and female extension personnel include resource map, mobility map, transect map, focus group discussion, venn diagram, seasonal calendar, SWOT analysis, semistructured interview, daily activity schedule, resource analysis, ...

  3. South African Journal of Agricultural Extension - Vol 36 (2007)

    African Journals Online (AJOL)

    The experience of Small Farmer Group (SFG) organisations in promoting agricultural extension in Tanzania · EMAIL FULL TEXT EMAIL FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. RM Wambura, DF Rutatora, R Øygard, M Shetto, O Ishumi, 39-52 ...

  4. Group theory

    CERN Document Server

    Scott, W R

    2010-01-01

    Here is a clear, well-organized coverage of the most standard theorems, including isomorphism theorems, transformations and subgroups, direct sums, abelian groups, and more. This undergraduate-level text features more than 500 exercises.

  5. Group Grammar

    Science.gov (United States)

    Adams, Karen

    2015-01-01

    In this article Karen Adams demonstrates how to incorporate group grammar techniques into a classroom activity. In the activity, students practice using the target grammar to do something they naturally enjoy: learning about each other.

  6. Computer group

    International Nuclear Information System (INIS)

    Bauer, H.; Black, I.; Heusler, A.; Hoeptner, G.; Krafft, F.; Lang, R.; Moellenkamp, R.; Mueller, W.; Mueller, W.F.; Schati, C.; Schmidt, A.; Schwind, D.; Weber, G.

    1983-01-01

    The computer groups has been reorganized to take charge for the general purpose computers DEC10 and VAX and the computer network (Dataswitch, DECnet, IBM - connections to GSI and IPP, preparation for Datex-P). (orig.)

  7. Group learning

    DEFF Research Database (Denmark)

    Pimentel, Ricardo; Noguira, Eloy Eros da Silva; Elkjær, Bente

    The article presents a study that aims at the apprehension of the group learning in a top management team composed by teachers in a Brazilian Waldorf school whose management is collective. After deciding to extend the school, they had problems recruiting teachers who were already trained based...... on the Steiner´s ideas, which created practical problems for conducting management activities. The research seeks to understand how that group of teachers collectively manage the school, facing the lack of resources, a significant heterogeneity in the relationships, and the conflicts and contradictions......, and they are interrelated to the group learning as the construction, maintenance and reconstruction of the intelligibility of practices. From this perspective, it can be said that learning is a practice and not an exceptional phenomenon. Building, maintaining and rebuilding the intelligibility is the group learning...

  8. Group technology

    International Nuclear Information System (INIS)

    Rome, C.P.

    1976-01-01

    Group Technology has been conceptually applied to the manufacture of batch-lots of 554 machined electromechanical parts which now require 79 different types of metal-removal tools. The products have been grouped into 7 distinct families which require from 8 to 22 machines in each machine-cell. Throughput time can be significantly reduced and savings can be realized from tooling, direct-labor, and indirect-labor costs

  9. Extensive Evaluation of the Conductor-like Screening Model for Real Solvents Method in Predicting Liquid-Liquid Equilibria in Ternary Systems of Ionic Liquids with Molecular Compounds.

    Science.gov (United States)

    Paduszyński, Kamil

    2018-04-12

    A conductor-like screening model for real solvents (COSMO-RS) is nowadays one of the most popular and commonly applied tools for the estimation of thermodynamic properties of complex fluids. The goal of this work is to provide a comprehensive review and analysis of the performance of this approach in calculating liquid-liquid equilibrium (LLE) phase diagrams in ternary systems composed of ionic liquid and two molecular compounds belonging to diverse families of chemicals (alkanes, aromatics, S/N-compounds, alcohols, ketones, ethers, carboxylic acid, esters, and water). The predictions are presented for extensive experimental database, including 930 LLE data sets and more than 9000 data points (LLE tie lines) reported for 779 unique ternary mixtures. An impact of the type of molecular binary subsystem on the accuracy of predictions is demonstrated and discussed on the basis of representative examples. The model's capability of capturing qualitative trends in the LLE distribution ratio and selectivity is also checked for a number of structural effects. Comparative analysis of two levels of quantum chemical theory (BP-TZVP-COSMO vs BP-TZVPD-FINE) for the input molecular data for COSMO-RS is presented. Finally, some general recommendations for the applicability of the model are indicated based on the analysis of the global performance as well as on the results obtained for systems relevant from the point of view of important separation problems.

  10. Molecular regulation of plant cell wall extensibility

    Science.gov (United States)

    Cosgrove, D. J.

    1998-01-01

    Gravity responses in plants often involve spatial and temporal changes in cell growth, which is regulated primarily by controlling the ability of the cell wall to extend. The wall is thought to be a cellulose-hemicellulose network embedded in a hydrated matrix of complex polysaccharides and a small amount of structural protein. The wall extends by a form of polymer creep, which is mediated by expansins, a novel group of wall-loosening proteins. Expansins were discovered during a molecular dissection of the "acid growth" behavior of cell walls. Expansin alters the rheology of plant walls in profound ways, yet its molecular mechanism of action is still uncertain. It lacks detectable hydrolytic activity against the major components of the wall, but it is able to disrupt noncovalent adhesion between wall polysaccharides. The discovery of a second family of expansins (beta-expansins) sheds light on the biological role of a major group of pollen allergens and implies that expansins have evolved for diverse developmental functions. Finally, the contribution of other processes to wall extensibility is briefly summarized.

  11. Group dynamics.

    Science.gov (United States)

    Scandiffio, A L

    1990-12-01

    Group dynamics play a significant role within any organization, culture, or unit. The important thing to remember with any of these structures is that they are made up of people--people with different ideas, motivations, background, and sometimes different agendas. Most groups, formal or informal, look for a leader in an effort to maintain cohesiveness of the unit. At times, that cultural bond must be developed; once developed, it must be nurtured. There are also times that one of the group no longer finds the culture comfortable and begins to act out behaviorally. It is these times that become trying for the leader as she or he attempts to remain objective when that which was once in the building phase of group cohesiveness starts to fall apart. At all times, the manager must continue to view the employee creating the disturbance as an integral part of the group. It is at this time that it is beneficial to perceive the employee exhibiting problem behaviors as a special employee, as one who needs the benefit of your experience and skills, as one who is still part of the group. It is also during this time that the manager should focus upon her or his own views in the area of power, communication, and the corporate culture of the unit that one has established before attempting to understand another's point of view. Once we understand our own motivation and accept ourselves, it is then that we may move on to offer assistance to another. Once we understand our insecurities recognizing staff dysfunction as a symptom of system dysfunction will not be so threatening to the concept of the manager that we perceive ourselves to be. It takes a secure person to admit that she or he favors staff before deciding to do something to change things. The important thing to know is that it can be done. The favored staff can find a new way of relating to others, the special employee can find new modes of behavior (and even find self-esteem in the process), the group can find new ways

  12. Sporadic simple groups and quotient singularities

    International Nuclear Information System (INIS)

    Cheltsov, I A; Shramov, C A

    2013-01-01

    We show that if a faithful irreducible representation of a central extension of a sporadic simple group with centre contained in the commutator subgroup gives rise to an exceptional (resp. weakly exceptional but not exceptional) quotient singularity, then that simple group is the Hall-Janko group (resp. the Suzuki group)

  13. Group representations

    CERN Document Server

    Karpilovsky, G

    1994-01-01

    This third volume can be roughly divided into two parts. The first part is devoted to the investigation of various properties of projective characters. Special attention is drawn to spin representations and their character tables and to various correspondences for projective characters. Among other topics, projective Schur index and projective representations of abelian groups are covered. The last topic is investigated by introducing a symplectic geometry on finite abelian groups. The second part is devoted to Clifford theory for graded algebras and its application to the corresponding theory

  14. Lego Group

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Pedersen, Torben; Slepniov, Dmitrij

    2010-01-01

    The last years’ rather adventurous journey from 2004 to 2009 had taught the fifth-largest toy-maker in the world - the LEGO Group - the importance of managing the global supply chain effectively. In order to survive the largest internal financial crisis in its roughly 70 years of existence......, the management had, among many initiatives, decided to offshore and outsource a major chunk of its production to Flextronics. In this pursuit of rapid cost-cutting sourcing advantages, the LEGO Group planned to license out as much as 80 per cent of its production besides closing down major parts...

  15. Quantum chemical calculations and molecular docking studies of 5-(4-chlorobenzylidene)thiazolidine-2,4-dione(CTD) and its mannich product 5-(4-chlorobenzylidene)-3-(morpholinomethyl)thiazolidine-2,4-dione (CMTD)

    Science.gov (United States)

    Fatma, Shaheen; Bishnoi, Abha; Verma, Anil Kumar; Singh, Vineeta; Srivastava, Krishna

    2018-04-01

    This work presents the synthesis of 5-(4-chlorobenzylidene)thiazolidine-2,4-dione (CTD) by Claisen condensation of thiazolidine-2,4-dione and mannich product of CTD, 5-(4-chlorobenzylidene)-3-(morpholinomethyl)thiazolidine-2,4-dione (CMTD). The static first hyperpolarizability values for thiazolidine-2,4-dione derivatives have been calculated as 10.28 × 10-30 esu for CTD and 19.42 × 10-30 esu for CMTD. The gradual increase in hyperpolarizability values of synthesized thiazolidine-2,4-dione derivatives from CTD to CMTD is due to the blockage of sbnd NH group on CTD by mannich reaction. The structures of these compounds have been derived by spectroscopic(IR, UV, Mass, 1H and 13C NMR) analysis as well as with the help of theoretical studies. The high values of first static hyperpolarizability indicate that the synthesized derivatives are suitable as non-linear optical (NLO) material. CTD with MIC value of 12.5 μg/mL can be developed as an alternative drug for the treatment of enteric fever. Calculated frontier orbital gap values suggest that the CMTD is a soft molecule with high chemical reactivity and is more polarizable as compared to the CTD. Molecular electrostatic potential is calculated for the optimized geometry of the molecules to estimate their chemical reactivity. The inhibitor CTD forms a stable complex with 3-dehydroquinase enzyme of Salmonella typhi. It is evident from the ligand receptor interactions and a binding affinity value of -5.88 kcal/mol and an inhibition constant of 49.22 μM. This is further confirmed by the experimental biological data. The molecular docking studies are supportive of the antibacterial activity of CTD exhibiting high inhibition constant and binding energy.

  16. An extension of Pohlmeyer's theorem

    International Nuclear Information System (INIS)

    Rosten, Oliver J

    2010-01-01

    Applying the exact renormalization group to scalar field theory in Euclidean space of general (not necessarily integer) dimension, it is proven that the only fixed point with vanishing anomalous dimension is the Gaussian one. The proof requires positivity of the two-point connected correlation function together with a technical assumption concerning solutions of the flow equation. The method, in which the representation of the flow equation as a heat equation plays a central role, extends directly to non-gauge theories with arbitrary matter content (though nonlinear sigma models are beyond the scope of the current method).

  17. On an extension of covariance

    International Nuclear Information System (INIS)

    Sebestyen, A.

    1975-07-01

    The principle of covariance is extended to coordinates corresponding to internal degrees of freedom. The conditions for a system to be isolated are given. It is shown how internal forces arise in such systems. Equations for internal fields are derived. By an interpretation of the generalized coordinates based on group theory it is shown how particles of the ordinary sense enter into the model and as a simple application the gravitational interaction of two pointlike particles is considered and the shift of the perihelion is deduced. (Sz.Z.)

  18. Informal groups

    NARCIS (Netherlands)

    E. van den Berg; P. van Houwelingen; J. de Hart

    2011-01-01

    Original title: Informele groepen Going out running with a group of friends, rather than joining an official sports club. Individuals who decide to take action themselves rather than giving money to good causes. Maintaining contact with others not as a member of an association, but through an

  19. The impact of brand extension fit, extension strategy and product exposure on attitudinal responses to brand extensions

    OpenAIRE

    Farstad, Lena Kvelland; Jabran, Mohammed

    2013-01-01

    Brand extensions have for decades been one of the most used strategies for growth, but the sad reality is that 8 out of 10 extensions fail, making the likelihood of failure unattractively high. In addition, competition and pressure on margins increases as retailers’ power improves due to proliferation of private labels. As a result, managers are eager for new innovative strategies that can differentiate their extension and improve likelihood of success. The purpose of this paper is therefore ...

  20. Clifford algebras, spinors, spin groups and covering groups

    International Nuclear Information System (INIS)

    Magneville, C.; Pansart, J.P.

    1991-03-01

    The Dirac equation uses matrices named Υ matrices which are representations of general algebraic structures associated with a metric space. These algebras are the Clifford algebras. In the first past, these algebras are studied. Then the notion of spinor is developed. It is shown that Majorana and Weyl spinors only exist for some particular metric space. In the second part, Clifford and spinor groups are studied. They may be interpreted as the extension of the notion of orthogonal group for Clifford algebras and their spaces for representation. The rotation of a spinor is computed. In the last part, the connexion between the spinor groups and the Universal Covering Groups is presented [fr

  1. Quantum-chemical insight into structure-reactivity relationship in 4,5,6,7-tetrahalogeno-1H-benzimidazoles: a combined X-ray, DSC, DFT/QTAIM, Hirshfeld surface-based, and molecular docking approach.

    Science.gov (United States)

    Latosińska, Jolanta Natalia; Latosińska, Magdalena; Maurin, Jan Krzysztof; Orzeszko, Andrzej; Kazimierczuk, Zygmunt

    2014-03-20

    The weak interaction patterns in 4,5,6,7-tetrahalogeno-1H-benzimidazoles, protein kinase CK2 inhibitors, in solid state are studied by the X-ray method and quantum chemistry calculations. The crystal structures of 4,5,6,7-tetrachloro- and 4,5,6,7-tetrabromo-1H-benzimidazole are determined by X-ray diffraction and refined to a final R-factor of 3.07 and 3.03%, respectively, at room temperature. The compound 4,5,6,7-tetrabromo-1H-benzimidazole, which crystallizes in the I41/a space group, is found to be isostructural with previously studied 4,5,6,7-tetraiodo-1H-benzimidazole in contrast to 4,5,6,7-tetrachloro-1H-benzimidazole, which crystallizes as triclinic P1̅ with 4 molecules in elementary unit. For 4,5,6,7-tetrachloro-1H-benzimidazole, differential scanning calorimetry (DSC) revealed a second order glassy phase transition at Tg = 95°/106° (heating/cooling), an indication of frozen disorder. The lack of 3D isostructurality found in all 4,5,6,7-tetrahalogeno-1H-benzimidazoles is elucidated on the basis of the intra- and intermolecular interactions (hydrogen bonding, van der Waals contacts, and C-H···π interactions). The topological Bader's Quantum Theory of Atoms in Molecules (QTAIM) and Spackman's Hirshfeld surface-based approaches reveal equilibration of electrostatic matching and dispersion van der Waals interactions between molecules consistent with the crystal site-symmetry. The weakening of van der Waals forces accompanied by increasing strength of the hydrogen bond (N-H···N) result in a decrease in the crystal site-symmetry and a change in molecular packing in the crystalline state. Crystal packing motifs were investigated with the aid of Hirshfeld surface fingerprint plots. The ordering 4,5,6,7-tetraiodo > 4,5,6,7-tetrabromo > 4,5,6,7-tetrachloro > 4,5,6,7-tetrafluoro reflects not only a decrease in crystal symmetry but also increase in chemical reactivity (electronic activation), which could explain some changes in biological activity of

  2. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group, established at the start of 2010, has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure There are now 55 CMS Centres worldwide that are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS offline and computing operations, hosting dedicated analysis efforts such as during the CMS Heavy Ion lead-lead running. With a majority of CMS sub-detectors now operating in a “shifterless” mode, many monitoring operations are now routinely performed from there, rather than in the main Control Room at P5. The CMS Communications Group, CERN IT and the EVO team are providing excellent videoconferencing support for the rapidly-increasing number of CMS meetings. In parallel, CERN IT and ...

  3. Group therapy

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    Full text: In his review 'Genesis of Unified Gauge Theories' at the symposium in Honour of Abdus Salam (June, page 23), Tom Kibble of Imperial College, London, looked back to the physics events around Salam from 1959-67. He described how, in the early 1960s, people were pushing to enlarge the symmetry of strong interactions beyond the SU(2) of isospin and incorporate the additional strangeness quantum number. Kibble wrote - 'Salam had students working on every conceivable symmetry group. One of these was Yuval Ne'eman, who had the good fortune and/or prescience to work on SU(3). From that work, and of course from the independent work of Murray Gell- Mann, stemmed the Eightfold Way, with its triumphant vindication in the discovery of the omega-minus in 1964.' Yuval Ne'eman writes - 'I was the Defence Attaché at the Israeli Embassy in London and was admitted by Salam as a part-time graduate student when I arrived in 1958. I started research after resigning from the Embassy in May 1960. Salam suggested a problem: provide vector mesons with mass - the problem which was eventually solved by Higgs, Guralnik, Kibble,.... (as described by Kibble in his article). I explained to Salam that I had become interested in symmetry. Nobody at Imperial College at the time, other than Salam himself, was doing anything in groups, and attention further afield was focused on the rotation - SO(N) - groups. Reacting to my own half-baked schemes, Salam told me to forget about the rotation groups he taught us, and study group theory in depth, directing me to Eugene Dynkin's classification of Lie subalgebras, about which he had heard from Morton Hamermesh. I found Dynkin incomprehensible without first learning about Lie algebras from Henri Cartan's thesis, which luckily had been reproduced by Dynkin in his 1946 thesis, using his diagram method. From a copy of a translation of Dynkin's thesis which I found in the British Museum Library, I

  4. Local fields and their extensions

    CERN Document Server

    Fesenko, I B

    2002-01-01

    This book offers a modern presentation of local fields whose spectacular development was initiated almost one hundred years ago by K. Hensel. The volume consists of nine chapters divided into four parts: arithmetic properties of local fields, class field theory for various types of local fields and generalizations, explicit formulas for the Hilbert pairing, and Milnor K-groups of fields and of local fields. The first three parts essentially simplify, revise, and update the first edition. This second edition contains about sixty additional pages reflecting several aspects of the developments in local number theory in the last ten years. Exercises point to many other paths for exploration. The book is designed for graduate students and research mathematicians interested in local number theory and its applications in arithmetic algebraic geometry.

  5. Glottic cancer with subglottic extension

    International Nuclear Information System (INIS)

    Ampil, F.L.; Menezes, C.-A.O.

    1997-01-01

    The outcomes of 27 patients with glottic cancer extending into the subglottis (GCSE) who were treated by surgery and radiation (n=17) or radiation alone (n=10) during a 13-year period were retrospectively reviewed. Since this study was nonrandomized and retrospective, the patient groups were not equally matched with regard to age (p>0.05), gender (p>0.30), or disease stage (p>0.05). The locoregional failure rate was 18±(95% CI) 20% in patients who received combined therapy and 40±31% in persons treated by radiation alone (p=0.20); the corresponding survival rates at two years were 53±24% and 42±31% (p>0.50). These findings suggest that GCSE may be better managed by a combination of surgery and radiotherapy than by the use of radiotherapy alone. (author)

  6. Operational data collection and analysis for nuclear plant life extension

    International Nuclear Information System (INIS)

    DuCharme, A.R.; Berg, R.M.; Bailey, T.L.

    1989-01-01

    This paper describes initial work undertaken by the US Department of Energy, through Sandia National Laboratories in Albuquerque, New Mexico, to define the operational data necessary for support of nuclear plant life extension (PLEX) programs. This work is being performed in coordination with the Working Group on Plant Life Extension of the US Nuclear Management and Resources Council. The intent of the effort is to use results gained initially from pilot PLEX programs a US BWR and a US PWR to build towards the use of ''PLEX indicators'' by which a plant's readiness for successful life extension can be measured. Another objective of the study was to examine chemistry data in detail to determine how well US plants are collecting, preserving, and trending the chemistry data that is important to PLEX. The methods used to disseminate this data to outside agencies and other utilities were studied. Finally, an analysis was made to determine additional chemistry data needed to support PLEX

  7. Scintigraphic characteristics of experimental myocardial infarct extension

    International Nuclear Information System (INIS)

    Kronenberg, M.W.; Wooten, N.E.; Friesinger, G.C.; Page, D.L.; Higgins, S.B.; Collins, J.C.; O'Connor, J.L.; Price, R.R.; Brill, A.B.

    1979-01-01

    Technetium-99m-stannous pyrophosphate scintiphotos were evaluated for diagnosing and quantitating myocardial infarct (MI) extension in sedated dogs. Infarction and extension were produced by serial left anterior descending coronary artery ligations at 0 and 48 hours. We compared serial scintiphoto data with regional myocardial blood flow (MBF) (microsphere technique) and infarct histopathology. In eight control dogs, the scintigraphic MI area was stable at 24, 48, and 72 hours. In each of 11 dogs undergoing extension, the MI area increased after the 48-hour occlusion, averaging a 48.9% increase (p < 0.001). Grossly, most extensions were mixtures of confluent necrosis and moderate (patchy) necrosis. MBF to confluent infarct tissue decreased significantly, allowing the documentation of extension by totaling the grams of newly flow-deprived tissue, but patchy infarct tissue had little flow deprivation, making it difficult to quantitate this type of extension accurately by flow criteria alone. Rarely, extension could be diagnosed using conventional histologic criteria. We concluded that the scintiphoto MI area was related quantitatively to infarct weight in both control and extension. However, it was not possible to determine that an increase in the MI scintiphoto area was an accurate predictor of the degree of extension using independent flow or pathologic criteria

  8. Assessment of extensive surgery for locally advanced lung cancer. Safety and efficacy of induction therapy

    International Nuclear Information System (INIS)

    Niwa, Hiroshi; Nakamae, Katsumi; Yamada, Takeshi; Kani, Hisanori; Maemoto, Katsutoshi; Mizuno, Takeo

    1999-01-01

    Locally advanced lung cancer has a poor prognosis, despite extensive surgery conducted in an effort to improve survival. We evaluated the safety and efficacy of induction therapy prior to extensive surgery for locally advanced lung cancer. Primary resection for lung cancer was done in 549 consecutive patients divided into three groups; 446 undergoing standard pulmonary resection (no extensive surgery), 87 undergoing extensive surgery without induction therapy, and 16 undergoing surgery after induction therapy. Morbidity was 23.5%, 28.6%, and 43.8%, respectively. The rate was significantly higher in the induction group compared with the no extensive surgery group (P<0.05). Surgical mortality was 0.67%, 3.4%, and 6.3%, respectively. The difference was statistically significant between the no extensive surgery and extensive surgery groups (P<0.02), and between the no extensive surgery and induction groups (P<0.02). Hospital mortality was 2.2%, 9.2%, and 6.3%, respectively. The rates were significantly higher in the extensive surgery (P<0.01) and induction (P<0.05) groups compared to the no extensive surgery group. Five-year survival was 50.3% for the patients who received induction therapy, and 14.7% for the patients who did not receive induction therapy. Survival differences between the induction and non induction groups were not significant, but some patients with T3 or T4 disease may benefit from induction therapy. The high morbidity of induction treatment should be recognized, and strict candidate selection and careful postoperative care used to help prevent increased mortality. (author)

  9. Computational screening of functional groups for capture of toxic industrial chemicals in porous materials.

    Science.gov (United States)

    Kim, Ki Chul; Fairen-Jimenez, David; Snurr, Randall Q

    2017-12-06

    A thermodynamic analysis using quantum chemical methods was carried out to identify optimal functional group candidates that can be included in metal-organic frameworks and activated carbons for the selective capture of toxic industrial chemicals (TICs) in humid air. We calculated the binding energies of 14 critical TICs plus water with a series of 10 functional groups attached to a naphthalene ring model. Using vibrational calculations, the free energies of adsorption were calculated in addition to the binding energies. Our results show that, in these systems, the binding energies and free energies follow similar trends. We identified copper(i) carboxylate as the optimal functional group (among those studied) for the selective binding of the majority of the TICs in humid air, and this functional group exhibits especially strong binding for sulfuric acid. Further thermodynamic analysis shows that the presence of water weakens the binding strength of sulfuric acid with the copper carboxylate group. Our calculations predict that functionalization of aromatic rings would be detrimental to selective capture of COCl 2 , CO 2 , and Cl 2 under humid conditions. Finally, we found that forming an ionic complex, H 3 O + HSO 4 - , between H 2 SO 4 and H 2 O via proton transfer is not favorable on copper carboxylate.

  10. NRU licence extension via integrated safety review

    Energy Technology Data Exchange (ETDEWEB)

    Mantifel, N. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    2014-07-01

    The National Research Reactor, NRU at AECL Chalk River Laboratories achieved first criticality in November 1957. The completion of an Integrated Safety Review (ISR) in 2011, and subsequent Global Assessment Report (GAR), and Integrated Implementation Plan (IIP) has given confidence in the safe and reliable operation of NRU, therefore extending the licensing case to safely and reliably operate NRU until 2021 and beyond (64+ years of operation). The key vehicle to achieve this confidence is the IIP, that resulted from the ISR. NRU's IIP is a 10 year plan that addresses the gaps identified in the ISR between modern codes and standards in a prioritized approach. AECL is currently in year 3 of the IIP execution, is on or ahead of schedule to complete the identified improvements. The IIP in conjunction with a License Condition Handbook has replaced the licensing protocol with the Canadian Nuclear Safety Commission, (CNSC). Execution of the IIP to plan supports the continued safe operation of NRU. The ISR was carried out with the recognition that the NRU reactor is a research and isotope producing reactor approaching license renewal and not a power reactor undergoing refurbishment and life extension. Therefore, the IIP is being executed while NRU continues to deliver on its three missions: production of medical isotopes, support for fuels and materials research, and serving as a high flux neutron source in support of research relying on neutron scattering. The IIP is grouped into 5 Global Issue Groups, (GIGs) to support focused execution. The activities and tasks within the five GIGs are being executed via a matrix organization through the use of the Chalk River Laboratories Corrective Action Program to ensure the assignment of actions, completion and evidence to support closure is documented and retained. This paper discusses the approach taken by AECL to license and ensure safe, reliable operation of NRU until 2021 and beyond. (author)

  11. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The CMS Communications Group, established at the start of 2010, has been strengthening the activities in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The Communications Group has invested a lot of effort to support the operations needs of CMS. Hence, the CMS Centres where physicists work on remote CMS shifts, Data Quality Monitoring, and Data Analysis are running very smoothly. There are now 55 CMS Centres worldwide, up from just 16 at the start of CMS data-taking. The latest to join are Imperial College London, the University of Iowa, and the Università di Napoli. The CMS Centre@CERN in Meyrin, which is now full repaired after the major flooding at the beginning of the year, has been at the centre of CMS offline and computing operations, most recently hosting a large fraction of the CMS Heavy Ion community during the lead-lead run. A number of sub-detector shifts can now take pla...

  12. Group play

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects of the v......Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects...... of the various formats used by RPGs on the gaming experience. This article presents the results of an empirical study, examining how multi-player tabletop RPGs are affected as they are ported to the digital medium. Issues examined include the use of disposition assessments to predict play experience, the effect...... of group dynamics, the influence of the fictional game characters and the comparative play experience between the two formats. The results indicate that group dynamics and the relationship between the players and their digital characters, are integral to the quality of the gaming experience in multiplayer...

  13. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS Offline and Computing operations, and a number of subdetector shifts can now take place there, rather than in the main Control Room at P5. A new CMS meeting room has been equipped for videoconferencing in building 42, next to building 40. Our building 28 meeting room and the facilities at P5 will be refurbished soon and plans are underway to steadily upgrade the ageing equipment in all 15 CMS meeting rooms at CERN. The CMS evaluation of the Vidyo tool indicates that it is not yet ready to be considered as a potential replacement for EVO. The Communications Group provides the CMS-TV (web) cha...

  14. On the homology and the cohomology of certain polycyclic groups

    International Nuclear Information System (INIS)

    Majumdar, S.

    1987-10-01

    The homology and the cohomology of infinite non-abelian split extensions of cyclic groups by cyclic groups have been computed through construction of nice free resolutions for these groups. (author). 16 refs

  15. Agricultural extension, research, and development for increased ...

    African Journals Online (AJOL)

    The challenges of food security and agricultural development in South Africa cannot simply be solved by limiting extension and research development to the public sector. However, if shortcomings arise in the public sector while addressing extension, research and development, the potential involvement of the private sector ...

  16. Extension Sustainability Camp: Design, Implementation, and Evaluation

    Science.gov (United States)

    Brain, Roslynn; Upton, Sally; Tingey, Brett

    2015-01-01

    Sustainability Camps provide an opportunity for Extension educators to be in the forefront of sustainability outreach and to meet the growing demand for sustainability education. This article shares development, implementation, and evaluation of an Extension Sustainability Camp for youth, grades 4-6. Camp impact was measured via daily pre-and…

  17. Effective Use of Facebook for Extension Professionals

    Science.gov (United States)

    Mains, Mark; Jenkins-Howard, Brooke; Stephenson, Laura

    2013-01-01

    As the use of social media increases, Extension is challenged to stay relevant with cliental by using digital tools. This article illustrates how Facebook can be part of Extension's repertoire of methods for communication, program implementation, education, and marketing. This allows professionals to build social networking capacity with…

  18. Towards professionalism in agricultural extension: The professional ...

    African Journals Online (AJOL)

    Towards professionalism in agricultural extension: The professional registration of Extensionists in South Africa – A dream or a reality? The role of the South African Society of Extensionists in South Africa – A dream or a reality? The role of the South African Society of Agricultural Extension (SASAE)

  19. Enhancing academic reading skills through extensive reading ...

    African Journals Online (AJOL)

    Abstract. The current study explores the feasibility of an extensive reading programme in the context of a low-income country (Mozambique), as well as the influence of extensive reading on academic reading. The programme took over 4 months and was conducted among 30 students majoring in Journalism at the Eduardo ...

  20. Job satisfaction of extension agents towards innovation ...

    African Journals Online (AJOL)

    The study assessed job satisfaction of extension agents towards innovation dissemination to fish farmers in Lagos State, Nigeria. A simple random sampling technique was used to select 44 extension officers from which data were collected. A structured questionnaire consisting of 6 personal characteristics, 23 management ...