Student’s mental model, misconceptions, troublesome knowledge, and threshold concept on thermochemistry with DToM-POE

Science.gov (United States)

Wiji, W.; Mulyani, S.

2018-05-01

The purpose of this study is to obtain a profile of students' mental models, misconceptions, troublesome knowledge, and threshold concept on thermochemistry. The subjects in this study were 35 students. The method used in this research was descriptive method with instruments Diagnostic Test of Mental Model - Prediction, Observation, and Explanation (DToM-POE). The results showed that the students' ability to predict, observe, and explain ΔH of neutralization reaction of NaOH with HCl was still lacking. Most students tended to memorize chemical concepts related to symbolic level and they did not understand the meaning of the symbols used. Furthermore, most students were unable to connect the results of observations at the macroscopic level with the symbolic level to determine ΔH of neutralization reaction of NaOH with HCl. Then, most students tended to give an explanation by a net ionic equation or a chemical reaction equation at the symbolic level when explaining ΔH of neutralization reaction at the submicroscopic level. In addition, there are seven misconceptions, three troublesome knowledges, and three threshold concepts held by students on thermochemistry.

Database of Small Molecule Thermochemistry for Combustion

KAUST Repository

Goldsmith, C. Franklin; Magoon, Gregory R.; Green, William H.

2012-01-01

High-accuracy ab initio thermochemistry is presented for 219 small molecules relevant in combustion chemistry, including many radical, biradical, and triplet species. These values are critical for accurate kinetic modeling. The RQCISD(T)/cc-PV∞QZ//B3LYP/6-311++G(d,p) method was used to compute the electronic energies. A bond additivity correction for this method has been developed to remove systematic errors in the enthalpy calculations, using the Active Thermochemical Tables as reference values. On the basis of comparison with the benchmark data, the 3σ uncertainty in the standard-state heat of formation is 0.9 kcal/mol, or within chemical accuracy. An uncertainty analysis is presented for the entropy and heat capacity. In many cases, the present values are the most accurate and comprehensive numbers available. The present work is compared to several published databases. In some cases, there are large discrepancies and errors in published databases; the present work helps to resolve these problems. © 2012 American Chemical Society.

Database of Small Molecule Thermochemistry for Combustion

KAUST Repository

Goldsmith, C. Franklin

2012-09-13

High-accuracy ab initio thermochemistry is presented for 219 small molecules relevant in combustion chemistry, including many radical, biradical, and triplet species. These values are critical for accurate kinetic modeling. The RQCISD(T)/cc-PV∞QZ//B3LYP/6-311++G(d,p) method was used to compute the electronic energies. A bond additivity correction for this method has been developed to remove systematic errors in the enthalpy calculations, using the Active Thermochemical Tables as reference values. On the basis of comparison with the benchmark data, the 3σ uncertainty in the standard-state heat of formation is 0.9 kcal/mol, or within chemical accuracy. An uncertainty analysis is presented for the entropy and heat capacity. In many cases, the present values are the most accurate and comprehensive numbers available. The present work is compared to several published databases. In some cases, there are large discrepancies and errors in published databases; the present work helps to resolve these problems. © 2012 American Chemical Society.

MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES

Science.gov (United States)

Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine...

The Effect of Stick Stiffness of Friction Models on the Bending Behavior in Non-Bonded Flexible Risers

OpenAIRE

Dai, Tianjiao; Ye, Naiquan; Sævik, Svein

2017-01-01

This paper investigates the effect of stick stiffness on the bending behavior in non-bonded flexible risers. The stick stiffness was normally implemented in the friction model for calculating the friction stress between layers in such structures. As the stick stiffness may be too small to achieve the plane-surfaces-remain-plane assumption under low contact pressure in some friction models [1], a new friction model was proposed for maintaining the constant stick stiffness in the present work. ...

Thermochemistry of a Biomimetic and Rubisco-Inspired CO2 Capture System from Air

Directory of Open Access Journals (Sweden)

Andrew Muelleman

2016-07-01

Full Text Available In theoretical studies of chemical reactions the reaction thermochemistry is usually reported for the stoichiometric reaction at standard conditions (ΔG°, ΔH°, ΔS°. We describe the computation of the equilibrium concentrations of the CO2-adducts for the general capture reaction CO2 + Capture System ⇆ CO2-adduct (GCR and the rubisco-type capture reaction CO2 + Capture System ⇆ CO2-adduct + H2O (RCR with consideration of the reaction CO2(g ⇆ CO2(aq via Henry’s law. The resulting equations are evaluated and graphically illustrated as a function of atmospheric CO2 concentration and as a function of temperature. The equations were applied to the thermochemistry of small molecule rubisco-model reactions and series of additional model reactions to illustrate the range of the Gibbs free enthalpy for the effective reversible capture and of the reaction entropy for economic CO2 release at elevated temperature. A favorable capture of free enthalpy is of course a design necessity, but not all exergonic reactions are suitable CO2 capture systems. Successful CO2 capture systems must allow for effective release as well, and this feature is controlled by the reaction entropy. The principle of using a two-pronged capture system to ensure a large negative capture entropy is explained and highlighted in the graphical abstract. It is hoped that the presentation of the numerical examples provides useful guidelines for the design of more efficient capture systems.

The development of learning material using learning cycle 5E model based stem to improve students’ learning outcomes in Thermochemistry

Science.gov (United States)

sugiarti, A. C.; suyatno, S.; Sanjaya, I. G. M.

2018-04-01

The objective of this study is describing the feasibility of Learning Cycle 5E STEM (Science, Technology, Engineering, and Mathematics) based learning material which is appropriate to improve students’ learning achievement in Thermochemistry. The study design used 4-D models and one group pretest-posttest design to obtain the information about the improvement of sudents’ learning outcomes. The subject was learning cycle 5E based STEM learning materials which the data were collected from 30 students of Science class at 11th Grade. The techniques used in this study were validation, observation, test, and questionnaire. Some result attain: (1) all the learning materials contents were valid, (2) the practicality and the effectiveness of all the learning materials contents were classified as good. The conclution of this study based on those three condition, the Learnig Cycle 5E based STEM learning materials is appropriate to improve students’ learning outcomes in studying Thermochemistry.

Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

Energy Technology Data Exchange (ETDEWEB)

Classen, Nathan Robert [Iowa State Univ., Ames, IA (United States)

2002-01-01

The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular β C-H insertion mechanism.

Exact and Effective Pair-Wise Potential for Protein-Ligand Interactions Obtained from a Semiempirical Energy Partition

Directory of Open Access Journals (Sweden)

André Melo

2008-09-01

Full Text Available In this work, the partition method introduced by Carvalho and Melo was used to study the complex between Cucurbita maxima trypsin inhibitor (CMTI-I and glycerol at the AM1 level. An effective potential, combining non-bonding and polarization plus charge transfer (PLCT terms, was introduced to evaluate the magnitude of the interaction between each amino acid and the ligand. In this case study, the nonbonding–PLCT noncompensation characterizes the stabilization energy of the association process in study. The main residues (Gly29, Cys3 and Arg5 with net attractive effects and Arg1 (with a net repulsive effect, responsible by the stability of protein-ligand complex, are associated with large nonbonding energies non-compensated by PLCT effects. The results obtained enable us to conclude that the present decomposition scheme can be used for understanding the cohesive phenomena in proteins.

Processing of low-quality bauxite feedstock by thermochemistry-Bayer method

Directory of Open Access Journals (Sweden)

О. А. Дубовиков

2016-11-01

Full Text Available The modern production of aluminum which by its global output ranks first among the non-ferrous metals includes three main stages: ore extraction, its processing into alumina and, finally, the production of primary aluminum. Alumina production from bauxites,  being the  primary raw material in the  alumina industry,  is based  on two main methods: the Bayer method and the sintering method developed in Russia under the lead of an academician Nikolay Semenovich Kurnakov. Alumina production by the Bayer’s method is more cost effective,  but  has  higher  requirements to the  quality of the bauxite feedstock.  A great deal  of research has  been carried  out on low quality bauxites focusing firstly on finding ways to enrich the feedstock, secondly on improving the combined sequential Bayer-sintering method and thirdly on developing new hydrometallurgical ways for bauxites processing. Mechanical methods of bauxite enrichment have not yet brought any positive outcome, and a development of new hydrometallurgical high alkaline  autoclave process  faced  significant hardware  difficulties not addressed so far. For efficient processing of such low quality bauxite feedstock it is suggested to use a universal thermochemistry-Bayer method, which was developed in St. Petersburg Mining University under  the lead  of  Nikolay Ivanovich Eremin, allows to process different substandard bauxite feedstock and has a competitive costing as compared to the sintering method and combined methods. The main stages of thermochemistry-Bayer method are thermal activation of feedstock, its further desiliconization with the alkaline solution and leaching of the resultant bauxite product  under Bayer’s method. Despite high energy consumption at  the baking stage,  it  allows to condition the  low quality bauxite feedstock by neutralizing a variety of technologically harmful impurities such as organic matter, sulfide sulfur, carbonates, and at the

Analyses of Non-bonding Length, Partial Atomics Charge and Electrostatic Energy from Molecular Dynamics Simulation of Phospholipase A2 – Substrate

Directory of Open Access Journals (Sweden)

Nirwan Syarif

2016-11-01

Full Text Available This paper reports molecular dynamics simulation of phospholipase A2 (PLA2– substrate that has been done. Non-bonding length, partial atomic charge and electrostatic energy were used to evaluation the interaction between PLA2 and substrate. The research was subjected for three types of PLA2 of different sources, i.e, homo sapien, bovinus and porcinus, by using computer files of their molecular structures. The files with code 3elo, 1bp2, dan 1y6o were downloaded from protein data bank. Substrate structure can be found in 1y60 and was separated from its enzyme structure and docked into two other PLA2 structures for simulation purpose. Molecular dynamics simulations were done for 30000 steps with constant in number of molecules, volume and temperature (NVT. The results showed the existing of flip-flop mechanism as basic feature of PLA2 – substrate reactions. Interaction length analysis results indicated the presence of water molecules on the structures of 1bp2 and 3elo at the time of the simulation was completed. The existence of aspagine at the reaction site confirmed the theory that this amino acid is responsible for the survival of the reaction. the electrostatic energy increased substantially in the interaction after homo sapien PLA2 (3elo and Bovinus (1bp2 with the substrate. Inverse effect took place in the PLA porcinus (1y6o.

Predicted thermochemistry and unimolecular kinetics of nitrous sulfide

DEFF Research Database (Denmark)

Marshall, Paul; Gao, Yide; Glarborg, Peter

2011-01-01

The geometry of N2S was obtained at the CCSD(T)/aug-cc-pV(T + d)Z level of theory and energies with coupled-cluster single double triple (CCSD(T)) and basis sets up to aug-cc-pV(6 + d)Z. After correction for anharmonic zero-point energy, core-valence correlation, correlation up to CCSDT...... crossing point between singlet and triplet potential energy curves is found at r(N-N) approximate to 1.105 angstrom and r(N-S) approximate to 2.232 angstrom, with an energy 72 kJ mol (1) above N-2 + S(P-3). Application of Troe's unimolecular formalism yields the low-pressure-limiting rate constant......(Q) and relativistic effects, D-0 for the N-S bond is estimated as 71.9 kJ mol (1), and the corresponding thermochemistry for N2S is Delta H-f(0)degrees = 205.4 kJ mol(-1) and Delta H-f(298)degrees = 202.6 kJ mol(-1) with an uncertainty of +/- 2.5 kJ mol(-1). Using CCSD(T)/aug-cc-pV(T + d) theory the minimum energy...

Spectroscopy, Thermochemistry, and Reactivity of Lanthanide and Actinide Molecules

International Nuclear Information System (INIS)

Morse, Michael D.; Armentrout, Peter B.

2012-01-01

The research undertaken under this grant is described in this document. The document describes progress in the construction of an instrument for recording photodissociation action spectra of mass-selected cryo-cooled cations. The instrument is not yet functional, but we anticipate trapping ions and conducting photodissociation experiments before the end of the year. It also describes resonant two-photon ionization spectra that have been recorded for uranium mononitride (UN) in the visible portion of the spectrum. These experiments are still underway at the present time. Although the spectra are a bit difficult to properly fit, due to upper state perturbations, it appears that the molecule has a ground state with (Omega) = 3.5 and a bond length of approximately 1.76 (angstrom). Finally, results on the thermochemistry and reactivity of Th + are presented. In these studies the bond energies of the following bonds have been determined: D 0 (Th + -2O) = 10.2 ± 0.2 eV; D0(Th + -N) = 6.69 ± 0.35 eV; D0(Th + -O) = 8.40 ± 0.28 eV; D 0 (OTh + -O) = 1.8 ± 0.4 eV.

Thermochemistry and micro-kinetic analysis of methanol synthesis on ZnO (0001)

DEFF Research Database (Denmark)

Medford, Andrew James; Sehested, Jens; Rossmeisl, Jan

2014-01-01

In this work, we examine the thermochemistry of methanol synthesis intermediates using density functional theory (DFT) and analyze the methanol synthesis reaction network using a steady-state micro-kinetic model. The energetics for methanol synthesis over Zn-terminated ZnO (0001) are obtained from...... DFT calculations using the RPBE and BEEF-vdW functionals. The energies obtained from the two functionals are compared and it is determined that the BEEF-vdW functional is more appropriate for the reaction. The BEEF-vdW energetics are used to construct surface phase diagrams as a function of CO, H2O......, and H2 chemical potentials. The computed binding energies along with activation barriers from literature are used as inputs for a mean-field micro-kinetic model for methanol synthesis including the CO and CO2 hydrogenation routes and the water–gas shift reaction. The kinetic model is used to investigate...

A Hierarchy of Homodesmotic Reactions for Thermochemistry

Science.gov (United States)

Schleyer, Paul v. R.

2009-01-01

Chemical equations that balance bond types and atom hybridization to different degrees are often used in computational thermochemistry, for example, to increase accuracy when lower levels of theory are employed. We expose the widespread confusion over such classes of equations and demonstrate that the two most widely used definitions of “homodesmotic” reactions are not equivalent. New definitions are introduced and a consistent hierarchy of reaction classes (RC1 – RC5) for hydrocarbons is constructed: isogyric (RC1) ⊇ isodesmic (RC2) ⊇ hypohomodesmotic (RC3) ⊇ homodesmotic (RC4) ⊇ hyperhomodesmotic (RC5). Each of these successively conserves larger molecular fragments. The concept of isodesmic bond separation reactions is generalized to all classes in this hierarchy, providing a unique sectioning of a given molecule for each reaction type. Several ab initio and density functional methods are applied to the bond separation reactions of 38 hydrocarbons containing five or six carbon atoms. RC4 and RC5 reactions provide bond separation enthalpies with errors consistently less than 0.4 kcal mol−1 across a wide range of theoretical levels, performing significantly better than the other reaction types and far superior to atomization routes. Our recommended bond separation reactions were demonstrated by determining the enthalpies of formation (at 298 K) of 1,3,5-hexatriyne (163.7 ± 0.4 kcal mol−1), 1,3,5,7-octatetrayne (217.6 ± 0.6 kcal mol−1), the larger polyynes C10H2 through C26H2, and an infinite acetylenic carbon chain. PMID:19182999

Thermochemistry of sarcosine and sarcosine anhydride: Theoretical and experimental studies

International Nuclear Information System (INIS)

Amaral, Luísa M.P.F.; Santos, Ana Filipa L.O.M.; Ribeiro da Silva, Maria das Dores M.C.; Notario, Rafael

2013-01-01

Highlights: ► Study on the Energetics of the sarcosine and sarcosine anhydride. ► Experimental and computational thermochemistry of sarcosine and its anhydride. ► Ab initio calculations for two amino acid derivatives by G3(MP2)//B3LYP method. -- Abstract: The standard molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, of sarcosine, −(388.0 ± 1.0) kJ · mol −1 , and sarcosine anhydride, −(334.5 ± 1.6) kJ · mol −1 , were calculated by combining, for each compound, the standard molar enthalpy of formation, in the crystalline phase, and the standard molar enthalpy of sublimation, derived from measurements of the standard massic energies of combustion by static bomb combustion calorimetry, and from measurements of vapour pressures by the Knudsen mass-loss effusion method, respectively. The standard (p o = 0.1 MPa) molar enthalpies, entropies and Gibbs functions of sublimation, at T = 298.15 K, were also calculated. A theoretical study at the G3 and G4 levels has been carried out, and the calculated enthalpies of formation have been compared with the experimental ones

Development and evaluation of a thermochemistry concept inventory for college-level general chemistry

Science.gov (United States)

Wren, David A.

The research presented in this dissertation culminated in a 10-item Thermochemistry Concept Inventory (TCI). The development of the TCI can be divided into two main phases: qualitative studies and quantitative studies. Both phases focused on the primary stakeholders of the TCI, college-level general chemistry instructors and students. Each phase was designed to collect evidence for the validity of the interpretations and uses of TCI testing data. A central use of TCI testing data is to identify student conceptual misunderstandings, which are represented as incorrect options of multiple-choice TCI items. Therefore, quantitative and qualitative studies focused heavily on collecting evidence at the item-level, where important interpretations may be made by TCI users. Qualitative studies included student interviews (N = 28) and online expert surveys (N = 30). Think-aloud student interviews (N = 12) were used to identify conceptual misunderstandings used by students. Novice response process validity interviews (N = 16) helped provide information on how students interpreted and answered TCI items and were the basis of item revisions. Practicing general chemistry instructors (N = 18), or experts, defined boundaries of thermochemistry content included on the TCI. Once TCI items were in the later stages of development, an online version of the TCI was used in expert response process validity survey (N = 12), to provide expert feedback on item content, format and consensus of the correct answer for each item. Quantitative studies included three phases: beta testing of TCI items (N = 280), pilot testing of the a 12-item TCI (N = 485), and a large data collection using a 10-item TCI ( N = 1331). In addition to traditional classical test theory analysis, Rasch model analysis was also used for evaluation of testing data at the test and item level. The TCI was administered in both formative assessment (beta and pilot testing) and summative assessment (large data collection), with

Termoquímica na Unicamp: depoimento sobre uma jornada de 25 anos Thermochemistry at Unicamp: testimony of a 25 year journey

Directory of Open Access Journals (Sweden)

Aécio Pereira Chagas

1999-06-01

Full Text Available This article describes the progress of a group of investigation on thermochemistry, which started in 1972. A homemade calorimeter was employed to provide quantitative support to the information on interative effect between lanthanide cations and halides or pseudohalides, in non-aqueous solvents, previously derived from conductometric titrations. However, the features of this instrument were not able to detect the thermal effects. Therefore, the great input to the group came from the acquisition of an LKB commercial apparatus, by the University in 1975. Considering the historical development of the coordination chemistry in Brazil, which was previously dedicated to strutural features of adducts, without focusing the energetic envolved in any coordinationcompound. Since starting the thermochemistry study, numerous masters and doctoral thesis covering more than a hundred adducts and a reasonable number of chelates, were presented systematizing data in order to understand the behavior of this kind of coordination compounds (C. Airoldi and A. P. Chagas, Coord. Chem. Rev. 1992, 119, 29. This knowledge enabled an extension of the study to include some heterogeneous systems formed by natural or synthetic materials like immobilized silica gel, lamellar phosphate, phosphonate or sulphate compounds, clays, polysaccharides, chrysotile, soils, etc. Many students are now engaged as staff members in Universities, Research Instituitions or other private institutions, developing many activities. Due to a multiplying effect on the formation of researchers, the group is now reaching the fourth generation.

Thermochemistry of 6-propyl-2-thiouracil: An experimental and computational study

Energy Technology Data Exchange (ETDEWEB)

Szterner, Piotr; Galvão, Tiago L.P.; Amaral, Luísa M.P.F.; Ribeiro da Silva, Maria D.M.C., E-mail: mdsilva@fc.up.pt; Ribeiro da Silva, Manuel A.V.

2014-07-01

Highlights: • Thermochemistry of 6-propyl-2-thiouracil – experimental and computational study. • Vapor pressure study of the 6-propyl-2-thiouracil by Knudsen effusion technique. • Enthalpies of formation of 6-propyl-2-thiouracil by rotating combustion calorimetry. • Accurate computational calculations (G3 and G4 composite methods) were performed. - Abstract: The standard (p{sup o} = 0.1 MPa) molar enthalpy of formation of 6-propyl-2-thiouracil was derived from its standard molar energy of combustion, in oxygen, to yield CO{sub 2} (g), N{sub 2} (g) and H{sub 2}SO{sub 4}·115H{sub 2}O (l), at T = 298.15 K, measured by rotating bomb combustion calorimetry. The vapor pressures as function of temperature were measured by the Knudsen effusion technique and the standard molar enthalpy of sublimation, Δ{sub cr}{sup g}H{sub m}{sup o}, at T = 298.15 K, was derived by the Clausius–Clapeyron equation. These two thermodynamic parameters yielded the standard molar enthalpy of formation, in the gaseous phase, at T = 298.15 K: −(142.5 ± 1.9) kJ mol{sup −1}. This value was compared with estimates obtained from very accurate computational calculations using the G3 and G4 composite methods.

A continuum-based structural modeling approach for cellulose nanocrystals (CNCs)

Science.gov (United States)

Mehdi Shishehbor; Fernando L. Dri; Robert J. Moon; Pablo D. Zavattieri

2018-01-01

We present a continuum-based structural model to study the mechanical behavior of cel- lulose nanocrystals (CNCs), and analyze the effect of bonded and non-bonded interactions on the mechanical properties under various loading conditions. In particular, this model assumes the uncoupling between the bonded and non-bonded interactions and their be- havior is obtained...

Elementary Steps of Syngas Reactions on Mo2C(001): Adsorption Thermochemistry and Bond Dissociation

Energy Technology Data Exchange (ETDEWEB)

Medford, Andrew

2012-02-16

Density functional theory (DFT) and ab initio thermodynamics are applied in order to investigate the most stable surface and subsurface terminations of Mo{sub 2}C(001) as a function of chemical potential and in the presence of syngas. The Mo-terminated (001) surface is then used as a model surface to evaluate the thermochemistry and energetic barriers for key elementary steps in syngas reactions. Adsorption energy scaling relations and Broensted-Evans-Polanyi relationships are established and used to place Mo{sub 2}C into the context of transition metal surfaces. The results indicate that the surface termination is a complex function of reaction conditions and kinetics. It is predicted that the surface will be covered by either C{sub 2}H{sub 2} or O depending on conditions. Comparisons to transition metals indicate that the Mo-terminated Mo{sub 2}C(001) surface exhibits carbon reactivity similar to transition metals such as Ru and Ir, but is significantly more reactive towards oxygen.

The Cold Shock Domain of YB-1 Segregates RNA from DNA by Non-Bonded Interactions.

Directory of Open Access Journals (Sweden)

Vladislav Kljashtorny

Full Text Available The human YB-1 protein plays multiple cellular roles, of which many are dictated by its binding to RNA and DNA through its Cold Shock Domain (CSD. Using molecular dynamics simulation approaches validated by experimental assays, the YB1 CSD was found to interact with nucleic acids in a sequence-dependent manner and with a higher affinity for RNA than DNA. The binding properties of the YB1 CSD were close to those observed for the related bacterial Cold Shock Proteins (CSP, albeit some differences in sequence specificity. The results provide insights in the molecular mechanisms whereby YB-1 interacts with nucleic acids.

Complete analysis of steady and transient missile aerodynamic/propulsive/plume flowfield interactions

Science.gov (United States)

York, B. J.; Sinha, N.; Dash, S. M.; Hosangadi, A.; Kenzakowski, D. C.; Lee, R. A.

1992-07-01

The analysis of steady and transient aerodynamic/propulsive/plume flowfield interactions utilizing several state-of-the-art computer codes (PARCH, CRAFT, and SCHAFT) is discussed. These codes have been extended to include advanced turbulence models, generalized thermochemistry, and multiphase nonequilibrium capabilities. Several specialized versions of these codes have been developed for specific applications. This paper presents a brief overview of these codes followed by selected cases demonstrating steady and transient analyses of conventional as well as advanced missile systems. Areas requiring upgrades include turbulence modeling in a highly compressible environment and the treatment of particulates in general. Recent progress in these areas are highlighted.

Interaction energy for a fullerene encapsulated in a carbon nanotorus

Science.gov (United States)

Sarapat, Pakhapoom; Baowan, Duangkamon; Hill, James M.

2018-06-01

The interaction energy of a fullerene symmetrically situated inside a carbon nanotorus is studied. For these non-bonded molecules, the main interaction originates from the van der Waals energy which is modelled by the 6-12 Lennard-Jones potential. Upon utilising the continuum approximation which assumes that there are infinitely many atoms that are uniformly distributed over the surfaces of the molecules, the total interaction energy between the two structures is obtained as a surface integral over the spherical and the toroidal surfaces. This analytical energy is employed to determine the most stable configuration of the torus encapsulating the fullerene. The results show that a torus with major radius around 20-22 Å and minor radius greater than 6.31 Å gives rise to the most stable arrangement. This study will pave the way for future developments in biomolecules design and drug delivery system.

On the Importance of Nonbonding Donor-Acceptor Interactions Involving PO2. Radicals: An ab Initio Study.

Science.gov (United States)

Bauzá, Antonio; Frontera, Antonio

2017-08-18

In this study, several σ-type and π-hole bonding complexes between PO 2 . radicals and electron-rich entities have been optimized at the RI-MP2/aug-cc-pVQZ level of theory. We have used Cl - , Br - , I - anions, and ethene, ethyne, HCN, HF, and H 2 O as Lewis bases. In addition, we have performed natural bond orbital (NBO) and Mulliken spin density analyses, highlighting the donor-acceptor nature of the interaction. Moreover, an interesting retro-donation from the single electron lone pair of the PO 2 . radical to the Lewis base also contributes to the stabilization of the complexes studied herein. Finally, the Bader's atoms-in-molecules (AIM) analysis of several complexes has been performed to further characterize the interactions discussed herein. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermochemistry of α-D-xylose(cr)

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Ribeiro da Silva, Maria D.M.C.; Lobo Ferreira, Ana I.M.C.; Shi, Quan; Woodfield, Brian F.; Goldberg, Robert N.

2013-01-01

Highlights: ► Well-characterized material. ► Oxygen bomb calorimetry. ► Heat capacities obtained by using a Physical Property Measurement System. ► Thermochemical Network Calculations. ► Accurate thermodynamic property values of a key biochemical substance. -- Abstract: The thermochemistry of α-D-xylose(cr) was studied by means of oxygen bomb calorimetry and a Physical Property Measurement System (PPMS) in zero magnetic field. The sample of α-D-xylose(cr) used in this study was one well-characterized by HPLC, Karl Fischer analysis, NMR, and by carbon dioxide analysis. The standard molar enthalpy of combustion was found to be Δ c H m o = −(2342.2 ± 0.8) kJ·mol −1 at T = 298.15 K and at the standard pressure p° = 0.1 MPa. The standard molar heat capacity for α-D-xylose(cr) was measured with the PPMS over the temperature range 1.9001 ⩽ T/K ⩽ 303.66. At T = 298.15 K, C p,m o = (178.1 ± 1.8) J·K −1 ·mol −1 . The values of C p,m o were fit as a function of T by using theoretical and empirical models for appropriate temperature ranges. The results of these fits were used to calculate values of C p,m o , the entropy increment Δ 0 T S m o , Δ 0 T H m o , and Φ m o =(Δ 0 T S m o -Δ 0 T H m o /T) from T = 0.5 K to T = 300 K. Derived quantities for α-D-xylose(cr) are the standard molar enthalpy of formation Δ f H m o = −(1054.5 ± 1.1) kJ·mol −1 , the third law standard molar entropy S m o = (175.3 ± 1.9) J·K −1 ·mol −1 , and the standard molar Gibbs energy of formation Δ f G m o = −(750.5 ± 1.0) kJ·mol −1 . A comparison of values of Δ c H m o and S m o for the five-carbon aldoses demonstrated a striking similarity in the values of these respective properties for α-D-xylose(cr), D-ribose(cr), and D-arabinose(cr). Thermochemical network calculations were performed that led to values of the standard formation properties at T = 298.15 K for a variety of biochemical substances: D-xylose(aq), D-xylose − (aq), D-xylose 2�

Thermal solid-state Z/E isomerization of 2-alkylidene-4-oxothiazolidines: effects of non-covalent interactions

Directory of Open Access Journals (Sweden)

ZDRAVKO DŽAMBASKI

2011-03-01

Full Text Available Configurational isomerization of stereo-defined 5-substituted and unsubstituted 2-alkylidene-4-oxothiazolidines (1 in the solid state, giving the Z/E mixtures in various ratios, was investigated by 1H-NMR spectroscopy, X-ray powder crystallography and differential scanning calorimetry (DSC. The Z/E composition can be rationalized in terms of non-covalent interactions, involving intermolecular and intramolecular hydrogen bonding and directional non-bonded 1,5-type S×××O interactions. X-Ray powder crystallography, using selected crystalline (Z-4-oxothiazolidine substrates, revealed transformation to the amorphous state during the irreversible Z®E process. A correlation between previous results on the Z/E isomerization in solution and now in the solid state was established.

A method for fast energy estimation and visualization of protein-ligand interaction

Science.gov (United States)

Tomioka, Nobuo; Itai, Akiko; Iitaka, Yoichi

1987-10-01

A new computational and graphical method for facilitating ligand-protein docking studies is developed on a three-dimensional computer graphics display. Various physical and chemical properties inside the ligand binding pocket of a receptor protein, whose structure is elucidated by X-ray crystal analysis, are calculated on three-dimensional grid points and are stored in advance. By utilizing those tabulated data, it is possible to estimate the non-bonded and electrostatic interaction energy and the number of possible hydrogen bonds between protein and ligand molecules in real time during an interactive docking operation. The method also provides a comprehensive visualization of the local environment inside the binding pocket. With this method, it becomes easier to find a roughly stable geometry of ligand molecules, and one can therefore make a rapid survey of the binding capability of many drug candidates. The method will be useful for drug design as well as for the examination of protein-ligand interactions.

A comprehensive iso-octane combustion model with improved thermochemistry and chemical kinetics

KAUST Repository

Atef, Nour

2017-02-05

Iso-Octane (2,2,4-trimethylpentane) is a primary reference fuel and an important component of gasoline fuels. Moreover, it is a key component used in surrogates to study the ignition and burning characteristics of gasoline fuels. This paper presents an updated chemical kinetic model for iso-octane combustion. Specifically, the thermodynamic data and reaction kinetics of iso-octane have been re-assessed based on new thermodynamic group values and recently evaluated rate coefficients from the literature. The adopted rate coefficients were either experimentally measured or determined by analogy to theoretically calculated values. Furthermore, new alternative isomerization pathways for peroxy-alkyl hydroperoxide (ȮOQOOH) radicals were added to the reaction mechanism. The updated kinetic model was compared against new ignition delay data measured in rapid compression machines (RCM) and a high-pressure shock tube. These experiments were conducted at pressures of 20 and 40 atm, at equivalence ratios of 0.4 and 1.0, and at temperatures in the range of 632–1060 K. The updated model was further compared against shock tube ignition delay times, jet-stirred reactor oxidation speciation data, premixed laminar flame speeds, counterflow diffusion flame ignition, and shock tube pyrolysis speciation data available in the literature. Finally, the updated model was used to investigate the importance of alternative isomerization pathways in the low temperature oxidation of highly branched alkanes. When compared to available models in the literature, the present model represents the current state-of-the-art in fundamental thermochemistry and reaction kinetics of iso-octane; and thus provides the best prediction of wide ranging experimental data and fundamental insights into iso-octane combustion chemistry.

Coarse graining of atactic polystyrene and its derivatives

Science.gov (United States)

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S.

2014-03-01

Capturing large length scales in polymers and soft matter while retaining atomistic properties is imperative to computational studies of dynamic systems. Here we present a new methodology developing coarse-grain model based on atomistic simulation of atactic polystyrene (PS). Similar to previous work by Fritz et al., each monomer is described by two coarse grained beads. In contrast to this earlier work where intramolecular potentials were based on Monte Carlo simulation of both isotactic and syndiotactic single PS molecule to capture stereochemistry, we obtained intramolecular interactions from a single molecular dynamics simulation of an all-atom atactic PS melts. The non-bonded interactions are obtained using the iterative Boltzmann inversion (IBI) scheme. This methodology has been extended to coarse graining of poly-(t-butyl-styrene) (PtBS). An additional coarse-grained bead is used to describe the t-butyl group. Similar to the process for PS, the intramolecular interactions are obtained from a single all atom atactic melt simulation. Starting from the non-bonded interactions for PS, we show that the IBI method for the non-bonded interactions of PtBS converges relatively fast. A generalized scheme for substituted PS is currently in development. We would like to acknowledge Prof. Kurt Kremer for helpful discussions during this work.

Development of non-bonded interaction parameters between graphene and water using particle swarm optimization.

Science.gov (United States)

Bejagam, Karteek K; Singh, Samrendra; Deshmukh, Sanket A

2018-05-05

New Lennard-Jones parameters have been developed to describe the interactions between atomistic model of graphene, represented by REBO potential, and five commonly used all-atom water models, namely SPC, SPC/E, SPC/Fw, SPC/Fd, and TIP3P/Fs by employing particle swarm optimization (PSO) method. These new parameters were optimized to reproduce the macroscopic contact angle of water on a graphene sheet. The calculated line tension was in the order of 10 -11 J/m for the droplets of all water models. Our molecular dynamics simulations indicate the preferential orientation of water molecules near graphene-water interface with one OH bond pointing toward the graphene surface. Detailed analysis of simulation trajectories reveals the presence of water molecules with ≤∼1, ∼2, and ∼4 hydrogen bonds at the surface of air-water interface, graphene-water interface, and bulk region of the water droplet, respectively. Presence of water molecules with ≤∼1 and ∼2 hydrogen bonds suggest the existence of water clusters of different sizes at these interfaces. The trends observed in the libration, bending, and stretching bands of the vibrational spectra are closely associated with these structural features of water. The inhomogeneity in hydrogen bond network of water at the air-water and graphene-water interface is manifested by broadening of the peaks in the libration band for water present at these interfaces. The stretching band for the molecules in water droplet shows a blue shift as compared to the pure bulk water, which conjecture the presence of weaker hydrogen bond network in a droplet. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Power transformations improve interpolation of grids for molecular mechanics interaction energies.

Science.gov (United States)

Minh, David D L

2018-02-18

A common strategy for speeding up molecular docking calculations is to precompute nonbonded interaction energies between a receptor molecule and a set of three-dimensional grids. The grids are then interpolated to compute energies for ligand atoms in many different binding poses. Here, I evaluate a smoothing strategy of taking a power transformation of grid point energies and inverse transformation of the result from trilinear interpolation. For molecular docking poses from 85 protein-ligand complexes, this smoothing procedure leads to significant accuracy improvements, including an approximately twofold reduction in the root mean square error at a grid spacing of 0.4 Å and retaining the ability to rank docking poses even at a grid spacing of 0.7 Å. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Economic analysis of the hydrogen production by means of the thermo-chemistry process iodine-sulfur with nuclear energy

International Nuclear Information System (INIS)

Solorzano S, C.; Francois L, J. L.

2011-11-01

In this work an economic study was realized about a centralized plant of hydrogen production that works by means of a thermo-chemistry cycle of sulfur-iodine and uses heat coming from a nuclear power plant of IV generation, with base in the software -Hydrogen Economic Evaluation Programme- obtained through the IAEA. The sustainable technology that is glimpsed next for the generation of hydrogen is to great scale and based on processes of high temperature coupled to nuclear power plants, being the most important the cycle S-I and the electrolysis to high temperature, for what objective references are presented that can serve as base for the taking of decisions for its introduction in Mexico. After detailing the economic models that uses the software for the calculation of the even cost of hydrogen production and the characteristics, so much of the nuclear plant constituted by fourth generation reactors, as of the plant of hydrogen production, is proposed a -base- case, obtaining a preliminary even cost of hydrogen production with this process; subsequently different cases are studied starting from which are carried out sensibility analysis in several parameters that could rebound in this cost, taking into account that these reactors are still in design and planning stages. (Author)

A quantitative analysis of weak intermolecular interactions & quantum chemical calculations (DFT) of novel chalcone derivatives

Energy Technology Data Exchange (ETDEWEB)

Chavda, Bhavin R., E-mail: chavdabhavin9@gmail.com; Dubey, Rahul P.; Patel, Urmila H. [Department of Physics, Sardar Patel University, Vallabh Vidyanagar-388120, Gujarat (India); Gandhi, Sahaj A. [Bhavan’s Shri I.L. Pandya Arts-Science and Smt. J.M. shah Commerce College, Dakar, Anand -388001, Gujarat, Indian (India); Barot, Vijay M. [P. G. Center in Chemistry, Smt. S. M. Panchal Science College, Talod, Gujarat 383 215 (India)

2016-05-06

The novel chalcone derivatives have widespread applications in material science and medicinal industries. The density functional theory (DFT) is used to optimized the molecular structure of the three chalcone derivatives (M-I, II, III). The observed discrepancies between the theoretical and experimental (X-ray data) results attributed to different environments of the molecules, the experimental values are of the molecule in solid state there by subjected to the intermolecular forces, like non-bonded hydrogen bond interactions, where as isolated state in gas phase for theoretical studies. The lattice energy of all the molecules have been calculated using PIXELC module in Coulomb –London –Pauli (CLP) package and is partitioned into corresponding coulombic, polarization, dispersion and repulsion contributions. Lattice energy data confirm and strengthen the finding of the X-ray results that the weak but significant intermolecular interactions like C-H…O, Π- Π and C-H… Π plays an important role in the stabilization of crystal packing.

Thermochemistry of mixed explosives

International Nuclear Information System (INIS)

Janney, J.L.; Rogers, R.N.

1982-01-01

In order to predict thermal hazards of high-energy materials, accurate kinetics constants must be determined. Predictions of thermal hazards for mixtures of high-energy materials require measurements on the mixtures, because interactions among components are common. A differential-scanning calorimeter (DSC) can be used to observe rate processes directly, and isothermal methods enable detection of mechanism changes. Rate-controlling processes will change as components of a mixture are depleted, and the correct depletion function must be identified for each specific stage of a complex process. A method for kinetics measurements on mixed explosives can be demonstrated with Composition B is an approximately 60/40 mixture of RDX and TNT, and is an important military explosive. Kinetics results indicate that the mator process is the decomposition of RDX in solution in TNT with a perturbation caused by interaction between the two components. It is concluded that a combination of chemical kinetics and experimental self-heating procedures provides a good approach to the production of predictive models for thermal hazards of high-energy materials. Systems involving more than one energy-contributing component can be studied. Invalid and dangerous predictive models can be detected by a failure of agreement between prediction and experiment at a specific size, shape, and density. Rates of thermal decomposition for Composition B appear to be modeled adequately for critical-temperature predictions with the following kinetics constants: E = 180.2 kJ mole -1 and Z = 4.62 X 10 16 s -1

Photoionization-photoelectron research

Energy Technology Data Exchange (ETDEWEB)

Berkowitz, J.; Ruscic, B. [Argonne National Laboratory, IL (United States)

1993-12-01

The photoionization research program is aimed at understanding the basic processes of interaction of vacuum ultraviolet (VUV) light with atoms and molecules. This research provides valuable information on both thermochemistry and dynamics. Recent studies include atoms, clusters, hydrides, sulfides and an important fluoride.

Thermochemistry analyses for transformation of C6 glucose compound into C9, C12 and C15 alkanes using density functional theory

Science.gov (United States)

Verma, Anand Mohan; Kishore, Nanda

2017-02-01

The hydrolysis of cellulose fraction of biomass yields C6 glucose which further can be transformed into long-chain hydrocarbons by C-C coupling. In this study, C6 glucose is transformed into three chain alkanes, namely, C9, C12 and C15 using C-C coupling reactions under the gas and aqueous phase milieus. The geometry optimisation and vibrational frequency calculations are carried out at well-known hybrid-GGA functional, B3LYP with the basis set of 6-31+g(d,p) under the density functional theory framework. The single point energetics are calculated at M05-2X/6-311+g(3df,2p) level of theory. All thermochemical properties are calculated over a wide range of temperature between 300 and 900 K at an interval of 100 K. The thermochemistry suggested that the aqueous phase behaviour is suitable for the hydrolysis of sugar into long-chain alkanes compared to gas-phase environment. The hydrodeoxygenation reactions under each reaction pathway are found as most favourable reactions in both phases; however, aqueous phase dominates over gas phase in all discussed thermodynamic parameters.

Problem solving - an interactive active method for teaching the thermokinetic concept

Directory of Open Access Journals (Sweden)

Odochian Lucia

2014-07-01

Full Text Available The paper describes a strategy that uses problem solving to teach the thermokinetic concept, based on student’s previously established proficiency in thermochemistry and kinetics. Chemistry teachers often use this method because it ensures easy achievement of both formative and informative science skills. This teaching strategy is tailored for students that prove special intellectual resources, Olympiad participants and to those who find chemistry a potential professional route

An extended hybrid density functional (X3LYP) with improved descriptions of nonbond interactions and thermodynamic properties of molecular systems

Science.gov (United States)

Xu, Xin; Zhang, Qingsong; Muller, Richard P.; Goddard, William A.

2005-01-01

We derive here the form for the exact exchange energy density for a density that decays with Gaussian-type behavior at long range. This functional is intermediate between the B88 and the PW91 exchange functionals. Using this modified functional to match the form expected for Gaussian densities, we propose the X3LYP extended functional. We find that X3LYP significantly outperforms Becke three parameter Lee-Yang-Parr (B3LYP) for describing van der Waals and hydrogen bond interactions, while performing slightly better than B3LYP for predicting heats of formation, ionization potentials, electron affinities, proton affinities, and total atomic energies as validated with the extended G2 set of atoms and molecules. Thus X3LYP greatly enlarges the field of applications for density functional theory. In particular the success of X3LYP in describing the water dimer (with Re and De within the error bars of the most accurate determinations) makes it an excellent candidate for predicting accurate ligand-protein and ligand-DNA interactions.

Teaching Experiment to Elucidate a Cation-Pi Effect in an Alkyne Cycloaddition Reaction and Illustrate Hypothesis-Driven Design of Experiments

Science.gov (United States)

St.Germain, Elijah J.; Horowitz, Andrew S.; Rucco, Dominic; Rezler, Evonne M.; Lepore, Salvatore D.

2017-01-01

An organic chemistry experiment is described that is based on recent research to elucidate a novel cation-pi interaction between tetraalkammonium cations and propargyl hydrazines. This nonbonded interaction is a key component of the mechanism of ammonium-catalyzed intramolecular cycloaddition of nitrogen to the terminal carbon of a C-C triple bond…

A continuum-based structural modeling approach for cellulose nanocrystals (CNCs)

Science.gov (United States)

Shishehbor, Mehdi; Dri, Fernando L.; Moon, Robert J.; Zavattieri, Pablo D.

2018-02-01

We present a continuum-based structural model to study the mechanical behavior of cellulose nanocrystals (CNCs), and analyze the effect of bonded and non-bonded interactions on the mechanical properties under various loading conditions. In particular, this model assumes the uncoupling between the bonded and non-bonded interactions and their behavior is obtained from atomistic simulations. Our results indicates that the major contribution to the tensile and bending stiffness is mainly due to the cellulose chain stiffness, and the shear behavior is mainly governed by Van der Waals (VdW) forces. In addition, we report a negligible torsional stiffness, which may explain the CNC tendency to easily twist under very small or nonexistent torques. In addition, the sensitivity of geometrical imperfection on the mechanical properties using an analytical model of the CNC structure was investigated. Our results indicate that the presence of imperfections have a small influence on the majority of the elastic properties. Finally, it is shown that a simple homogeneous and orthotropic representation of a CNC under bending underestimates the contribution of non-bonded interaction leading up to 60% error in the calculation of the bending stiffness of CNCs. On the other hand, the proposed model can lead to more accurate predictions of the elastic behavior of CNCs. This is the first step toward the development of a more efficient model that can be used to model the inelastic behavior of single and multiple CNCs.

Adsorption properties of the molecule resveratrol on CNT(8,0-10) nanotube: Geometry optimization, molecular structure, spectroscopic (NMR, UV/Vis, excited state), FMO, MEP and HOMO-LUMO investigations

Science.gov (United States)

Sheikhi, Masoome; Shahab, Siyamak; Khaleghian, Mehrnoosh; Hajikolaee, Fatemeh Haji; Balakhanava, Iryna; Alnajjar, Radwan

2018-05-01

In the present work the adsorption properties of the molecule Resveratrol (RSV) (trans-3,5,4‧-Trihydroxystilbene) on CNT(8,0-10) nanotube was investigated by Density Functional Theory (DFT) in the gaseous phase for the first time. The non-bonded interaction effects of compounds RSV and CNT(8,0-10) nanotube on the electronic properties, chemical shift tensors and natural charge were determined and discussed. The electronic spectra of the RSV and the complex CNT(8,0-10)/RSV in the gaseous phase were calculated by Time Dependent Density Functional Theory (TD-DFT) for investigation of the maximum wavelength value of the RSV before and after the non-bonded interaction with the CNT(8,0-10) nanotube and molecular orbitals involved in the formation of absorption spectrum of the complex RSV at maximum wavelength.

PREDICTING CHEMICAL REACTIVITY OF HUMIC SUBSTANCES FOR MINERALS AND XENOBIOTICS: USE OF COMPUTATIONAL CHEMISTRY, SCANNING PROBE MICROSCOPY AND VIRTUAL REALITY

Science.gov (United States)

In this chapter we review the literature on scanning probe microscopy (SPM), virtual reality (VR), and computational chemistry and our earlier work dealing with modeling lignin, lignin-carbohydrate complexes (LCC), humic substances (HSs) and non-bonded organo-mineral interactions...

Characterising non-covalent interactions with the Cambridge Structural Database.

Science.gov (United States)

Lommerse, J P; Taylor, R

1997-02-01

This review describes how the CSD can be used to study non-covalent interactions. Several different types of information may be obtained. First, the relative frequencies of various interactions can be studied; for example, we have shown that the terminal oxygen atoms of phosphate groups accept hydrogen bonds far more often than the linkage oxygens. Secondly, information can be obtained about the geometries of nonbonded contacts; for example, hydrogen bonds to P-O groups rarely form along the extension of the P-O bond, whereas short contacts between oxygen and carbon-bound iodine show a strong preference for linear C-I ... O angles. Thirdly, the CSD can be searched for novel interactions which may be exploited in inhibitor design; for example, the I ... O contacts just mentioned, and N-H ... pi hydrogen bonds. Finally, the CSD can suggest synthetic targets for medicinal chemistry; for example, molecules containing delocalised electron deficient groups such as trimethylammonium, pyridinium, thaizolium and dinitrophenyl have a good chance of binding to an active-site tryptophan. Although the CSD contains small-molecule crystal structures, not protein-ligand complexes, there is considerable evidence that the contacts seen in the two types of structures are similar. We have illustrated this a number of times in the present review and additional evidence has been given previously by Klebe. The major advantages of the CSD are its size, diversity and experimental accuracy. For these reasons, it is a useful tool for modellers engaged in rational inhibitor design.

An extended hybrid density functional (X3LYP) with improved descriptions of nonbond interactions and thermodynamic properties of molecular systems

OpenAIRE

Xu, Xin; Zhang, Qingsong; Muller, Richard P.; Goddard, William A., III

2005-01-01

We derive here the form for the exact exchange energy density for a density that decays with Gaussian-type behavior at long range. This functional is intermediate between the B88 and the PW91 exchange functionals. Using this modified functional to match the form expected for Gaussian densities, we propose the X3LYP extended functional. We find that X3LYP significantly outperforms Becke three parameter Lee–Yang–Parr (B3LYP) for describing van der Waals and hydrogen bond interactions, while per...

Molecular interactions in biomineralized hydroxyapatite amino acid modified nanoclay: In silico design of bone biomaterials

International Nuclear Information System (INIS)

Katti, Dinesh R.; Sharma, Anurag; Ambre, Avinash H.; Katti, Kalpana S.

2015-01-01

A simulations driven approach to design of a novel biomaterial nanocomposite system is described in this study. Nanoclays modified with amino acids (OMMT) were used to mineralize hydroxyapatite (HAP), mimicking biomineralization. Representative models of organically modified montmorillonite clay (OMMT) and OMMT-hydroxyapatite (OMMT-HAP) were constructed using molecular dynamics and validated using X-ray Diffraction (XRD), Fourier Transforms Infrared (FTIR) spectroscopy and Transmission Electron Microscopy (TEM). Attractive interactions exist between Ca atoms of HAP and C=O group of aminovaleric acid, indicating chelate formation in OMMT-HAP. Interaction energy maps describe molecular interactions among different constituents and their quantitative contributions in the OMMT and OMMT-HAP systems at both parallel and perpendicular orientations. High attractive and high repulsive interactions were found between PO 4 3− and MMT clay as well as aminovaleric molecules in OMMT-HAP perpendicular and parallel models. Large non-bonded interactions in OMMT-HAP indicate influence of neighboring environment on PO 4 3− in in situ HAPclay. Extensive hydrogen bonds were observed between functional hydrogen atoms of modifier and MMT clay in OMMT-HAP as compared to OMMT. Thus, HAP interacts with clay through the aminovaleric acid. This computational study provides a framework for materials design and selection for biomaterials used in tissue engineering and other areas of regenerative medicine. - Highlights: • Representative models of a hybrid nanoclay-hydroxyapatite biomaterial are built. • Interaction energy maps are constructed using a molecular dynamics. • Quantitative interactions between the three components of the biomaterial are found. • The modeling and experimental approach provides insight into the complex nanomaterial

Application of gradient-corrected density functional theory to the structures and thermochemistries of ScF3, TiF4, VF5, and CrF6

International Nuclear Information System (INIS)

Russo, T.V.; Martin, R.L.; Jeffrey Hay, P.

1995-01-01

Density functional theory (DFT) and Hartree--Fock (HF) calculations are reported for the family of transition metal fluorides ScF 3 , TiF 4 , VF 5 , and CrF 6 . Both HF and the local-density approximation (LDA) yield excellent agreement with experimental bond lengths, while the B-LYP gradient-corrected density functional gives bond lengths 0.04-0.05 A too long. An investigation of various combinations of exchange and correlation functionals shows that, for this series, the origin of this behavior lies in the Becke exchange functional. Much improved bond distances are found using the hybrid HF/DFT functional advocated by Becke. This approximation also leads to much improved thermochemistries. The LDA overestimates average bond energies in this series by 30-40 kcal/mol, whereas the B-LYP functional overbinds by only ∼8-12 kcal/mol, and the hybrid HF/DFT method overbinds by only ∼2 kcal/mol. The hybrid method predicts the octahedral isomer of CrF 6 to be more stable than the trigonal prismatic form by 14 kcal/mol. Comparison of theoretical vibrational frequencies with experiment supports the assignment of an octahedral geometry

Eight supramolecular assemblies constructed from bis(benzimidazole) and organic acids through strong classical hydrogen bonding and weak noncovalent interactions

Science.gov (United States)

Jin, Shouwen; Wang, Daqi

2014-05-01

Eight crystalline organic acid-base adducts derived from alkane bridged bis(N-benzimidazole) and organic acids (2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 5-sulfosalicylic acid and oxalic acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. Of the eight compounds five are organic salts (1, 4, 6, 7 and 8) and the other three (2, 3, and 5) are cocrystals. In all of the adducts except 1 and 8, the ratio of the acid and the base is 2:1. All eight supramolecular assemblies involve extensive intermolecular classical hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These weak interactions combined, all the complexes displayed 3D framework structure. The results presented herein indicate that the strength and directionality of the classical N+-H⋯O-, O-H⋯O, and O-H⋯N hydrogen bonds (ionic or neutral) and other nonbonding associations between acids and ditopic benzimidazoles are sufficient to bring about the formation of cocrystals or organic salts.

An electromagnetic induced transparency-like scheme for wireless power transfer using dielectric resonators

Science.gov (United States)

Elnaggar, Sameh Y.

2017-02-01

Similar to the hybridization of three atoms, three coupled resonators interact to form bonding, anti-bonding, and non-bonding modes. The non-bonding mode enables an electromagnetic induced transparency like transfer of energy. Here, the non-bonding mode, resulting from the strong electric coupling of two dielectric resonators and an enclosure, is exploited to show that it is feasible to transfer power over a distance comparable to the operating wavelength. In this scheme, the enclosure acts as a mediator. The strong coupling permits the excitation of the non-bonding mode with high purity. This approach is different from resonant inductive coupling, which works in the sub-wavelength regime. Optimal loads and the corresponding maximum efficiency are determined using two independent methods: Coupled Mode Theory and Circuit modelling. It is shown that, unlike resonant inductive coupling, the figure of merit depends on the enclosure quality and not on the load, which emphasizes the role of the enclosure as a mediator. Briefly after the input excitation is turned on, the energy in the receiver builds up via all coupled and spurious modes. As time elapses, all modes except the non-bonding cease to sustain. Due to the strong coupling between the dielectrics and the enclosure, such systems have unique properties such as high and uniform efficiency over large distances and minimal fringing fields. These properties suggest that electromagnetic induced transparency like schemes that rely on the use of dielectric resonators can be used to power autonomous systems inside an enclosure or find applications when exposure to the fields needs to be minimal. Finite Element computations are used to verify the theoretical predictions by determining the transfer efficiency, field profile, and coupling coefficients for two different systems. It is shown that the three resonators must be present for efficient power transfer; if one or more are removed, the transfer efficiency reduces

A ReaxFF-based molecular dynamics study of the mechanisms of interactions between reactive oxygen plasma species and the Candida albicans cell wall

Science.gov (United States)

Zhao, T.; Shi, L.; Zhang, Y. T.; Zou, L.; Zhang, L.

2017-10-01

Atmospheric pressure non-equilibrium plasmas have attracted significant attention and have been widely used to inactivate pathogens, yet the mechanisms underlying the interactions between plasma-generated species and bio-organisms have not been elucidated clearly. In this paper, reactive molecular dynamics simulations are employed to investigate the mechanisms of interactions between reactive oxygen plasma species (O, OH, and O2) and β-1,6-glucan (a model for the C. albicans cell wall) from a microscopic point of view. Our simulations show that O and OH species can break structurally important C-C and C-O bonds, while O2 molecules exhibit only weak, non-bonded interactions with β-1,6-glucan. Hydrogen abstraction from hydroxyl or CH groups occurs first in all bond cleavage mechanisms. This is followed by a cascade of bond cleavage and double bond formation events. These lead to the destruction of the fungal cell wall. O and OH have similar effects related to their bond cleavage mechanisms. Our simulation results provide fundamental insights into the mechanisms underlying the interactions between reactive oxygen plasma species and the fungal cell wall of C. albicans at the atomic level.

Martini Coarse-Grained Force Field : Extension to DNA

NARCIS (Netherlands)

Uusitalo, Jaakko J.; Ingolfsson, Helgi I.; Akhshi, Parisa; Tieleman, D. Peter; Marrink, Siewert J.

We systematically parameterized a coarsegrained (CG) model for DNA that is compatible with the Martini force field. The model maps each nucleotide into six to seven CG beads and is parameterized following the Martini philosophy. The CG nonbonded interactions are based on partitioning of the

Chiral discrimination in biomimetic systems: Phenylalanine

Indian Academy of Sciences (India)

WINTEC

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

Ab initio thermochemistry using optimal-balance models with isodesmic corrections: The ATOMIC protocol

Science.gov (United States)

Bakowies, Dirk

2009-04-01

A theoretical composite approach, termed ATOMIC for Ab initio Thermochemistry using Optimal-balance Models with Isodesmic Corrections, is introduced for the calculation of molecular atomization energies and enthalpies of formation. Care is taken to achieve optimal balance in accuracy and cost between the various components contributing to high-level estimates of the fully correlated energy at the infinite-basis-set limit. To this end, the energy at the coupled-cluster level of theory including single, double, and quasiperturbational triple excitations is decomposed into Hartree-Fock, low-order correlation (MP2, CCSD), and connected-triples contributions and into valence-shell and core contributions. Statistical analyses for 73 representative neutral closed-shell molecules containing hydrogen and at least three first-row atoms (CNOF) are used to devise basis-set and extrapolation requirements for each of the eight components to maintain a given level of accuracy. Pople's concept of bond-separation reactions is implemented in an ab initio framework, providing for a complete set of high-level precomputed isodesmic corrections which can be used for any molecule for which a valence structure can be drawn. Use of these corrections is shown to lower basis-set requirements dramatically for each of the eight components of the composite model. A hierarchy of three levels is suggested for isodesmically corrected composite models which reproduce atomization energies at the reference level of theory to within 0.1 kcal/mol (A), 0.3 kcal/mol (B), and 1 kcal/mol (C). Large-scale statistical analysis shows that corrections beyond the CCSD(T) reference level of theory, including coupled-cluster theory with fully relaxed connected triple and quadruple excitations, first-order relativistic and diagonal Born-Oppenheimer corrections can normally be dealt with using a greatly simplified model that assumes thermoneutral bond-separation reactions and that reduces the estimate of these

Carbon-13 nuclear magnetic resonance of strained organic molecules: III estimates of steric effects

International Nuclear Information System (INIS)

Seidl, P.R.; Leal, K.Z.; Costa, V.E.U.; Rio Grande do Sul Univ., Porto Alegre

1985-01-01

A study of cyclic organic molecules using carbon-13 NMR spectroscopy is analysed. The preparation of compounds and the use of norbornyl compounds as a basis for chemical shifts, bicyclic, tricyclic and tetracyclic derivatives are compared. Relevant distances, angles and non-bonded interactions are shown. (M.J.C.) [pt

Modeling the Structure of SARS 3a Transmembrane Protein Using a ...

Indian Academy of Sciences (India)

Modeling the structure of SARS 3a Transmembrane protein using a ... for the implicit membrane molecular dynamics (MD) simulations. ... The coordinates during the simulation were saved every 500 steps, and were used for analysis. ... the pair list for calculation of nonbonded interactions being updated after every 10 steps.

Thermochemistry and kinetics for 2-butanone-1-yl radical (CH2·C(═O)CH2CH3) reactions with O2.

Science.gov (United States)

Sebbar, N; Bozzelli, J W; Bockhorn, H

2014-01-09

Thermochemistry of reactants, intermediates, transition state structures, and products along with kinetics on the association of CH2·C(═O)CH2CH3 (2-butanone-1-yl) with O2 and dissociation of the peroxy adduct isomers are studied. Thermochemical properties are determined using ab initio (G3MP2B3 and G3) composite methods along with density functional theory (B3LYP/6-311g(d,p)). Entropy and heat capacity contributions versus temperature are determined from structures, vibration frequencies, and internal rotor potentials. The CH2·C(═O)CH2CH3 radical + O2 association results in a chemically activated peroxy radical with 27 kcal mol(-1) excess of energy. The chemically activated adduct can react to stabilized peroxy or hydroperoxide alkyl radical adducts, further react to lactones plus hydroxyl radical, or form olefinic ketones and a hydroperoxy radical. Kinetic parameters are determined from the G3 composite methods derived thermochemical parameters, and quantum Rice-Ramsperger-Kassel (QRRK) analysis to calculate k(E) with master equation analysis to evaluate falloff in the chemically activated and dissociation reactions. One new, not previously reported, peroxy chemistry reaction is presented. It has a low barrier path and involves a concerted reaction resulting in olefin formation, H2O elimination, and an alkoxy radical.

Evaluating interaction energies of weakly bonded systems using the Buckingham-Hirshfeld method

Science.gov (United States)

Krishtal, A.; Van Alsenoy, C.; Geerlings, P.

2014-05-01

We present the finalized Buckingham-Hirshfeld method (BHD-DFT) for the evaluation of interaction energies of non-bonded dimers with Density Functional Theory (DFT). In the method, dispersion energies are evaluated from static multipole polarizabilities, obtained on-the-fly from Coupled Perturbed Kohn-Sham calculations and partitioned into diatomic contributions using the iterative Hirshfeld partitioning method. The dispersion energy expression is distributed over four atoms and has therefore a higher delocalized character compared to the standard pairwise expressions. Additionally, full multipolar polarizability tensors are used as opposed to effective polarizabilities, allowing to retain the anisotropic character at no additional computational cost. A density dependent damping function for the BLYP, PBE, BP86, B3LYP, and PBE0 functionals has been implemented, containing two global parameters which were fitted to interaction energies and geometries of a selected number of dimers using a bi-variate RMS fit. The method is benchmarked against the S22 and S66 data sets for equilibrium geometries and the S22x5 and S66x8 data sets for interaction energies around the equilibrium geometry. Best results are achieved using the B3LYP functional with mean average deviation values of 0.30 and 0.24 kcal/mol for the S22 and S66 data sets, respectively. This situates the BHD-DFT method among the best performing dispersion inclusive DFT methods. Effect of counterpoise correction on DFT energies is discussed.

Coarse-grained models using local-density potentials optimized with the relative entropy: Application to implicit solvation

International Nuclear Information System (INIS)

Sanyal, Tanmoy; Shell, M. Scott

2016-01-01

Bottom-up multiscale techniques are frequently used to develop coarse-grained (CG) models for simulations at extended length and time scales but are often limited by a compromise between computational efficiency and accuracy. The conventional approach to CG nonbonded interactions uses pair potentials which, while computationally efficient, can neglect the inherently multibody contributions of the local environment of a site to its energy, due to degrees of freedom that were coarse-grained out. This effect often causes the CG potential to depend strongly on the overall system density, composition, or other properties, which limits its transferability to states other than the one at which it was parameterized. Here, we propose to incorporate multibody effects into CG potentials through additional nonbonded terms, beyond pair interactions, that depend in a mean-field manner on local densities of different atomic species. This approach is analogous to embedded atom and bond-order models that seek to capture multibody electronic effects in metallic systems. We show that the relative entropy coarse-graining framework offers a systematic route to parameterizing such local density potentials. We then characterize this approach in the development of implicit solvation strategies for interactions between model hydrophobes in an aqueous environment.

Dinitrogen Difluoride Chemistry. Improved Synthesis of cis- and trans-N2F2, Synthesis and Characterization of N2F+Sn2F9 High-Level Electronic Structure Calculations of cis-N2F2, trans-N2F2, F2N=N, and N2F+, and Mechanism of the trans-cis Isomerization of N2F2 (Preprint)

Science.gov (United States)

2010-05-01

approach developed at The University of Alabama and Washington State University for the prediction of accurate molecular thermochemistry was used to...Breit-Pauli Hamiltonian, the so-called mass-velocity and one- electron Darwin (MVD) corrections from configuration interaction singles and doubles...structure calculations can provide better values than experiment. A previous molecular orbital study by Lee and coworkers showed4 that the calculated values

Quantum mechanical force fields for condensed phase molecular simulations

Science.gov (United States)

Giese, Timothy J.; York, Darrin M.

2017-09-01

Molecular simulations are powerful tools for providing atomic-level details into complex chemical and physical processes that occur in the condensed phase. For strongly interacting systems where quantum many-body effects are known to play an important role, density-functional methods are often used to provide the model with the potential energy used to drive dynamics. These methods, however, suffer from two major drawbacks. First, they are often too computationally intensive to practically apply to large systems over long time scales, limiting their scope of application. Second, there remain challenges for these models to obtain the necessary level of accuracy for weak non-bonded interactions to obtain quantitative accuracy for a wide range of condensed phase properties. Quantum mechanical force fields (QMFFs) provide a potential solution to both of these limitations. In this review, we address recent advances in the development of QMFFs for condensed phase simulations. In particular, we examine the development of QMFF models using both approximate and ab initio density-functional models, the treatment of short-ranged non-bonded and long-ranged electrostatic interactions, and stability issues in molecular dynamics calculations. Example calculations are provided for crystalline systems, liquid water, and ionic liquids. We conclude with a perspective for emerging challenges and future research directions.

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

KAUST Repository

Minenkov, Yury

2016-03-22

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

Olefin epoxidation by molybdenum peroxo compound: molecular mechanism characterized by the electron localization function and catastrophe theory.

Science.gov (United States)

Berski, Slawomir; Sensato, Fabrício R; Polo, Victor; Andrés, Juan; Safont, V S

2011-02-03

The oxygen atom transfer reaction from the Mimoun-type complex MoO(η(2)-O(2))(2)OPH(3) to ethylene C(2)H(4) affording oxirane C(2)H(4)O has been investigated within the framework of the Bonding Evolution Theory in which the corresponding molecular mechanism is characterized by the topological analysis of the electron localization function (ELF) and Thom's catastrophe theory (CT). Topological analysis of ELF and electron density analysis reveals that all Mo-O bonds in MoO(η(2)-O(2))(2)OPH(3) and MoO(2)(η(2)-O(2))OPH(3) belong to closed-shell type interactions though negative values of total energy densities E(e)(r(BCP)) imply some covalent contribution. The peroxo O(i)-O(j) bonds are characterized as charge-shift or protocovalent species in which pairs of monosynaptic basins V(3)(O(i)), V(3)(O(j)) with a small electron population of ~0.25e each, are localized between core basins C(O(i)), C(O(j)). The oxygen transfer reaction from molybdenum diperoxo complex MoO(η(2)-O(2))(2)OPH(3) to C(2)H(4) system can be described by the following consecutive chemical events: (a) protocovalent peroxo O(2)-O(1) bond breaking, (b) reduction of the double C(1)=C(2) bond to single C(1)-C(2) bond in ethylene, (c) displacement of oxygen O(1) with two nonbonding basins, V(i=1,2)(O(1)), (d) increase of a number of the nonbonding basins to three (V(i=1,2,4)(O(1))); (e) reorganization and reduction in the number of nonbonding basis to two basins (V(i=1,4)(O(1))) resembling the ELF-topology of the nonbonding electron density in oxirane, (e) formation of the first O(1)-C(2) bond in oxirane, (f) C(2)-O(1)-C(2) ring closure, (g) formation of singular nonbonding basin V(O(2)) in new Mo=O(2) bond. The oxygen atom is transferred as an anionic moiety carrying a rather small electronic charge ranging from 0.5 to 0.7e.

Characterization of interactions of simvastatin, pravastatin, fluvastatin, and pitavastatin with bovine serum albumin: multiple spectroscopic and molecular docking.

Science.gov (United States)

Shi, Jie-Hua; Wang, Qi; Pan, Dong-Qi; Liu, Ting-Ting; Jiang, Min

2017-05-01

The binding interactions of simvastatin (SIM), pravastatin (PRA), fluvastatin (FLU), and pitavastatin (PIT) with bovine serum albumin (BSA) were investigated for determining the affinity of four statins with BSA through multiple spectroscopic and molecular docking methods. The experimental results showed that SIM, PRA, FLU, and PIT statins quenched the intrinsic fluorescence of BSA through a static quenching process and the stable stains-BSA complexes with the binding constants in the order of 10 4  M -1 at 298 K were formed through intermolecular nonbond interaction. The values of ΔH 0 , ΔS 0 and ΔG 0 in the binding process of SIM, PRA, FLU, and PIT with BSA were negative at the studied temperature range, suggesting that the binding process of four statins and BSA was spontaneous and the main interaction forces were van der Waals force and hydrogen-bonding interactions. Moreover, the binding of four statins with BSA was enthalpy-driven process due to |ΔH°|>|TΔS°| under the studied temperature range. From the results of site marker competitive experiments and molecular docking, subdomain IIIA (site II) was the primary binding site for SIM, PRA, FLU, and PIT on BSA. The results of UV-vis absorption, synchronous fluorescence, 3D fluorescence and FT-IR spectra proved that the slight change in the conformation of BSA, while the significant changes in the conformation of SIM, PRA, FLU, and PIT drug in statin-BSA complexes, indicating that the flexibility of statin molecules plays an important role in increasing the stability of statin-BSA complexes.

A transferable coarse-grained model for diphenylalanine: How to represent an environment driven conformational transition

Science.gov (United States)

Dalgicdir, Cahit; Sensoy, Ozge; Peter, Christine; Sayar, Mehmet

2013-12-01

One of the major challenges in the development of coarse grained (CG) simulation models that aim at biomolecular structure formation processes is the correct representation of an environment-driven conformational change, for example, a folding/unfolding event upon interaction with an interface or upon aggregation. In the present study, we investigate this transferability challenge for a CG model using the example of diphenylalanine. This dipeptide displays a transition from a trans-like to a cis-like conformation upon aggregation as well as upon transfer from bulk water to the cyclohexane/water interface. Here, we show that one can construct a single CG model that can reproduce both the bulk and interface conformational behavior and the segregation between hydrophobic/hydrophilic medium. While the general strategy to obtain nonbonded interactions in the present CG model is to reproduce solvation free energies of small molecules representing the CG beads in the respective solvents, the success of the model strongly depends on nontrivial decisions one has to make to capture the delicate balance between the bonded and nonbonded interactions. In particular, we found that the peptide's conformational behavior is qualitatively affected by the cyclohexane/water interaction potential, an interaction that does not directly involve the peptide at all but merely influences the properties of the hydrophobic/hydrophilic interface. Furthermore, we show that a small modification to improve the structural/conformational properties of the CG model could dramatically alter the thermodynamic properties.

A transferable coarse-grained model for diphenylalanine: How to represent an environment driven conformational transition

International Nuclear Information System (INIS)

Dalgicdir, Cahit; Sensoy, Ozge; Sayar, Mehmet; Peter, Christine

2013-01-01

One of the major challenges in the development of coarse grained (CG) simulation models that aim at biomolecular structure formation processes is the correct representation of an environment-driven conformational change, for example, a folding/unfolding event upon interaction with an interface or upon aggregation. In the present study, we investigate this transferability challenge for a CG model using the example of diphenylalanine. This dipeptide displays a transition from a trans-like to a cis-like conformation upon aggregation as well as upon transfer from bulk water to the cyclohexane/water interface. Here, we show that one can construct a single CG model that can reproduce both the bulk and interface conformational behavior and the segregation between hydrophobic/hydrophilic medium. While the general strategy to obtain nonbonded interactions in the present CG model is to reproduce solvation free energies of small molecules representing the CG beads in the respective solvents, the success of the model strongly depends on nontrivial decisions one has to make to capture the delicate balance between the bonded and nonbonded interactions. In particular, we found that the peptide's conformational behavior is qualitatively affected by the cyclohexane/water interaction potential, an interaction that does not directly involve the peptide at all but merely influences the properties of the hydrophobic/hydrophilic interface. Furthermore, we show that a small modification to improve the structural/conformational properties of the CG model could dramatically alter the thermodynamic properties

A transferable coarse-grained model for diphenylalanine: How to represent an environment driven conformational transition

Energy Technology Data Exchange (ETDEWEB)

Dalgicdir, Cahit; Sensoy, Ozge; Sayar, Mehmet, E-mail: msayar@ku.edu.tr [College of Engineering, Koç University, 34450 Istanbul (Turkey); Peter, Christine [Max Planck Institute for Polymer Research, 55128 Mainz (Germany); Department of Chemistry, University of Konstanz, 78547 Konstanz (Germany)

2013-12-21

One of the major challenges in the development of coarse grained (CG) simulation models that aim at biomolecular structure formation processes is the correct representation of an environment-driven conformational change, for example, a folding/unfolding event upon interaction with an interface or upon aggregation. In the present study, we investigate this transferability challenge for a CG model using the example of diphenylalanine. This dipeptide displays a transition from a trans-like to a cis-like conformation upon aggregation as well as upon transfer from bulk water to the cyclohexane/water interface. Here, we show that one can construct a single CG model that can reproduce both the bulk and interface conformational behavior and the segregation between hydrophobic/hydrophilic medium. While the general strategy to obtain nonbonded interactions in the present CG model is to reproduce solvation free energies of small molecules representing the CG beads in the respective solvents, the success of the model strongly depends on nontrivial decisions one has to make to capture the delicate balance between the bonded and nonbonded interactions. In particular, we found that the peptide's conformational behavior is qualitatively affected by the cyclohexane/water interaction potential, an interaction that does not directly involve the peptide at all but merely influences the properties of the hydrophobic/hydrophilic interface. Furthermore, we show that a small modification to improve the structural/conformational properties of the CG model could dramatically alter the thermodynamic properties.

Elastic properties, reaction kinetics, and structural relaxation of an epoxy resin polymer during cure

Science.gov (United States)

Heili, Manon; Bielawski, Andrew; Kieffer, John

The cure kinetics of a DGEBA/DETA epoxy is investigated using concurrent Raman and Brillouin light scattering. Raman scattering allows us to monitor the in-situ reaction and quantitatively assess the degree of cure. Brillouin scattering yields the elastic properties of the system, providing a measure of network connectivity. We show that the adiabatic modulus evolves non-uniquely as a function of cure degree, depending on the cure temperature and the molar ratio of the epoxy. Two mechanisms contribute to the increase in the elastic modulus of the material during curing. First, there is the formation of covalent bonds in the network during the curing process. Second, following bond formation, the epoxy undergoes structural relaxation toward an optimally packed network configuration, enhancing non-bonded interactions. We investigate to what extent the non-bonded interaction contribution to structural rigidity in cross-linked polymers is reversible, and to what extent it corresponds to the difference between adiabatic and isothermal moduli obtained from static tensile, i.e. the so-called relaxational modulus. To this end, we simultaneously measure the adiabatic and isothermal elastic moduli as a function of applied strain and deformation rate.

Unraveling origins of the heterogeneous curvature dependence of polypeptide interactions with carbon nanostructures.

Science.gov (United States)

Jana, Asis K; Tiwari, Mrityunjay K; Vanka, Kumar; Sengupta, Neelanjana

2016-02-17

Emerging nanotechnology has rapidly broadened interfacial prospects of biological molecules with carbon nanomaterials (CNs). A prerequisite for effectively harnessing such hybrid materials is a multi-faceted understanding of their complex interfacial interactions as functions of the physico-chemical characteristics and the surface topography of the individual components. In this article, we address the origins of the curvature dependence of polypeptide adsorption on CN surfaces (CNSs), a phenomenon bearing an acute influence upon the behavior and activity of CN-protein conjugates. Our benchmark molecular dynamics (MD) simulations with the amphiphilic full-length amyloid beta (Aβ) peptide demonstrate that protein adsorption is strongest on the concave (inner) CN surface, weakest on the convex (outer) surface, and intermediary on the planar surface, in agreement with recent experimental reports. The curvature effects, however, are found to manifest non-uniformly between the amino acid subtypes. To understand the underlying interplay of the chemical nature of the amino acids and surface topography of the CNs, we performed high-level quantum chemical (QM) calculations with amino acid analogs (AAA) representing their five prominent classes, and convex, concave and planar CN fragments. Molecular electrostatic potential maps reveal pronounced curvature dependence in the mixing of electron densities, and a resulting variance in the stabilization of the non-covalently bound molecular complexes. Interestingly, our study revealed that the interaction trends of the high-level QM calculations were captured well by the empirical force field. The findings in this study have important bearing upon the design of carbon based bio-nanomaterials, and additionally, provide valuable insights into the accuracy of various computational techniques for probing non-bonded interfacial interactions.

Thermodynamics of hydrogen bonding and van der Waals interactions of organic solutes in solutions of imidazolium based ionic liquids: “Structure-property” relationships

International Nuclear Information System (INIS)

Varfolomeev, Mikhail A.; Khachatrian, Artashes A.; Akhmadeev, Bulat S.; Solomonov, Boris N.

2016-01-01

Highlights: • Solution enthalpies of organic solutes in imidazolium based ionic liquids were measured. • van der Waals interactions scale of imidazolium based ionic liquids was proposed. • Enthalpies of solvation of organic solutes in ionic liquids were determined. • Hydrogen bond enthalpies of organic solutes with ionic liquids were calculated. • Relationships between structure of ionic liquids and thermochemical data were obtained. - Abstract: In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n-alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents.

Thermodynamics of hydrogen bonding and van der Waals interactions of organic solutes in solutions of imidazolium based ionic liquids: “Structure-property” relationships

Energy Technology Data Exchange (ETDEWEB)

Varfolomeev, Mikhail A., E-mail: vma.ksu@gmail.com; Khachatrian, Artashes A.; Akhmadeev, Bulat S.; Solomonov, Boris N.

2016-06-10

Highlights: • Solution enthalpies of organic solutes in imidazolium based ionic liquids were measured. • van der Waals interactions scale of imidazolium based ionic liquids was proposed. • Enthalpies of solvation of organic solutes in ionic liquids were determined. • Hydrogen bond enthalpies of organic solutes with ionic liquids were calculated. • Relationships between structure of ionic liquids and thermochemical data were obtained. - Abstract: In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n-alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents.

Predictive Design of Interfacial Functionality in Polymer Matrix Composites

Science.gov (United States)

2017-05-24

conventional practice the materials design cycle involves the iterative synthesis of materials components in the laboratory, fabrication of a prototype...sible by using the Brillouin light scattering (BLS) technique and by sandwiching the samples between trans- parent fluoride-doped tin oxide (FTO...the role of bonding vs. non-bonding interactions. During 2015-16 PI Kieffer was on sabbatical leave, freed of teaching and service requirements. The

Covalent Linking Greatly Enhances Photoinduced Electron Transfer in Fullerene-Quantum Dot Nanocomposites: Time-Domain Ab Initio Study

DEFF Research Database (Denmark)

Chaban, Vitaly V.; Prezhdo, Victor; Prezhdo, Oleg

2013-01-01

, it leads to a notably weaker QD-C-60 interaction than a lengthy molecular bridge. We show that the ET rate in a nonbonded mixture of QDs and C-60 can be enhanced by doping. The photoinduced ET is promoted primarily by mid- and low-frequency vibrations. The study establishes the basic design principles...... for enhancing photoinduced charge separation in nanoscale light harvesting materials....

A multi-state coarse grained modeling approach for an intrinsically disordered peptide

Science.gov (United States)

Ramezanghorbani, Farhad; Dalgicdir, Cahit; Sayar, Mehmet

2017-09-01

Many proteins display a marginally stable tertiary structure, which can be altered via external stimuli. Since a majority of coarse grained (CG) models are aimed at structure prediction, their success for an intrinsically disordered peptide's conformational space with marginal stability and sensitivity to external stimuli cannot be taken for granted. In this study, by using the LKα 14 peptide as a test system, we demonstrate a bottom-up approach for constructing a multi-state CG model, which can capture the conformational behavior of this peptide in three distinct environments with a unique set of interaction parameters. LKα 14 is disordered in dilute solutions; however, it strictly adopts the α -helix conformation upon aggregation or when in contact with a hydrophobic/hydrophilic interface. Our bottom-up approach combines a generic base model, that is unbiased for any particular secondary structure, with nonbonded interactions which represent hydrogen bonds, electrostatics, and hydrophobic forces. We demonstrate that by using carefully designed all atom potential of mean force calculations from all three states of interest, one can get a balanced representation of the nonbonded interactions. Our CG model behaves intrinsically disordered in bulk water, folds into an α -helix in the presence of an interface or a neighboring peptide, and is stable as a tetrameric unit, successfully reproducing the all atom molecular dynamics simulations and experimental results.

Combustion science and engineering

CERN Document Server

Annamalai, Kalyan

2006-01-01

Introduction and Review of Thermodynamics Introduction Combustion Terminology Matter and Its Properties Microscopic Overview of Thermodynamics Conservation of Mass and Energy and the First Law of Thermodynamics The Second Law of Thermodynamics Summary Stoichiometry and Thermochemistry of Reacting Systems Introduction Overall Reactions Gas Analyses Global Conservation Equations for Reacting Systems Thermochemistry Summary Appendix Reaction Direction and Equilibrium Introduction Reaction Direction and Chemical Equilibrium Chemical Equilibrium Relations Vant Hoff Equation Adi

Intracomplex {pi}-{pi} stacking interaction between adjacent phenanthroline molecules in complexes with rare-earth nitrates: Crystal and molecular structures of bis(1,10-Phenanthroline)trinitratoytterbium and bis(1,10-Phenanthroline)trinitratolanthanum

Energy Technology Data Exchange (ETDEWEB)

Sadikov, G. G., E-mail: sadgg@igic.ras.ru; Antsyshkina, A. S.; Rodnikova, M. N.; Solonina, I. A. [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation)

2009-01-15

Crystals of the compounds Yb(NO{sub 3}){sub 3}(Phen){sub 2} and La(NO{sub 3}){sub 3}(Phen){sub 2} (Phen = 1,10-phenanthroline) are investigated using X-ray diffraction. It is established that there exist two different crystalline modifications: the main modification (phase 1) is characteristic of all members of the isostructural series, and the second modification (phase 2) is observed only for the Eu, Er, and Yb elements. It is assumed that the stability and universality of main phase 1 are associated with the occurrence of the nonbonded {pi}-{pi} stacking interactions between the adjacent phenanthroline ligands in the complexes. The indication of the interactions is a distortion of the planar shape of the Phen molecule (the folding of the metallocycle along the N-N line with a folding angle of 11{sup o}-13{sup o} and its 'boomerang' distortion). The assumption regarding the {pi}-{pi} stacking interaction is very consistent with the shape of the ellipsoids of atomic thermal vibrations, as well as with the data obtained from thermography and IR spectroscopy. An analysis of the structures of a number of rare-earth compounds has demonstrated that the intracomplex {pi}-{pi} stacking interactions directly contribute to the formation of supramolecular associates in the crystals, such as molecular dimers, supramolecules, chain and layered ensembles, and framework systems.

Electron-induced dry reforming of methane in a temperature-controlled dielectric barrier discharge reactor

KAUST Repository

Zhang, Xuming

2013-09-23

Dry reforming of methane has the potential to reduce the greenhouse gases methane and carbon dioxide and to generate hydrogen-rich syngas. In reforming methane, plasma-assisted reforming processes may have advantages over catalytic processes because they are free from coking and their response time for mobile applications is quick. Although plasma-assisted reforming techniques have seen recent developments, systematic studies that clarify the roles that electron-induced chemistry and thermo-chemistry play are needed for a full understanding of the mechanisms of plasma-assisted reformation. Here, we developed a temperature-controlled coaxial dielectric barrier discharge (DBD) apparatus to investigate the relative importance of electron-induced chemistry and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297-773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH4 and CO2, while thermo-chemistry influenced the product selectivities because they were found to depend on the background temperature. Comparisons with results from arc-jet reformation indicated that thermo-chemistry is an efficient conversion method. Our findings may improve designs of plasma-assisted reformers by using relatively hotter plasma sources. However, detailed chemical kinetic studies are needed. © 2013 IOP Publishing Ltd.

Electron-induced dry reforming of methane in a temperature-controlled dielectric barrier discharge reactor

International Nuclear Information System (INIS)

Zhang, Xuming; Cha, Min Suk

2013-01-01

Dry reforming of methane has the potential to reduce the greenhouse gases methane and carbon dioxide and to generate hydrogen-rich syngas. In reforming methane, plasma-assisted reforming processes may have advantages over catalytic processes because they are free from coking and their response time for mobile applications is quick. Although plasma-assisted reforming techniques have seen recent developments, systematic studies that clarify the roles that electron-induced chemistry and thermo-chemistry play are needed for a full understanding of the mechanisms of plasma-assisted reformation. Here, we developed a temperature-controlled coaxial dielectric barrier discharge (DBD) apparatus to investigate the relative importance of electron-induced chemistry and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297–773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH 4 and CO 2 , while thermo-chemistry influenced the product selectivities because they were found to depend on the background temperature. Comparisons with results from arc-jet reformation indicated that thermo-chemistry is an efficient conversion method. Our findings may improve designs of plasma-assisted reformers by using relatively hotter plasma sources. However, detailed chemical kinetic studies are needed. (paper)

Optimizing Solute-Solute Interactions in the GLYCAM06 and CHARMM36 Carbohydrate Force Fields Using Osmotic Pressure Measurements.

Science.gov (United States)

Lay, Wesley K; Miller, Mark S; Elcock, Adrian H

2016-04-12

GLYCAM06 and CHARMM36 are successful force fields for modeling carbohydrates. To correct recently identified deficiencies with both force fields, we adjusted intersolute nonbonded parameters to reproduce the experimental osmotic coefficient of glucose at 1 M. The modified parameters improve behavior of glucose and sucrose up to 4 M and improve modeling of a dextran 55-mer. While the modified parameters may not be applicable to all carbohydrates, they highlight the use of osmotic simulations to optimize force fields.

Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

KAUST Repository

Zhang, Xuming

2015-01-01

We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight from studying high-temperature and low-pressure conditions with similar reduced field intensities. In the tested range of background temperatures (297 < T < 773 K), we found that the conversion of methane and oxygen depended on both the electron-induced chemistry and the thermo-chemistry, whereas the chemical pathways to the products were overall controlled by the thermo-chemistry at a given temperature. We also found that the thermo-chemistry enhanced the plasma-assisted partial oxidation process. Our findings expand our understanding of the plasma-assisted partial oxidation process and may be helpful in the design of cost-effective plasma reformers. © 2014 The Combustion Institute.

Supramolecular interactions of oxidative stress biomarker glutathione with fluorone black

Science.gov (United States)

Hepel, Maria; Stobiecka, Magdalena

2018-03-01

Oxidative stress biomarkers, including glutathione (GSH) and related compounds, are involved in a variety of interactions enabling redox potential maintenance in living cells and protection against radicals. Since the oxidative stress is promoting and, in many cases, inducing serious illnesses, monitoring of GSH levels can aid in diagnostics and disease prevention. Herein, we report on the discovery of the formation of a supramolecular ensemble of GSH with fluorone black (9-phenyl fluorone, FB) which is optically active and enables sensitive determination of GSH by resonance elastic light scattering (RELS). We have found that supramolecular interactions of GSH with FB can be probed with spectroscopic, RELS, and electrochemical methods. Our investigations show that RELS intensity for FB solutions increases with GSH concentration while fluorescence emission of FB is not affected, as quenching begins only above 0.8 mM GSH. The UV-Vis difference spectra show a positive peak at 383 nm and a negative peak at 458 nm, indicating a higher-energy absorbing complex in comparison to the non-bonded FB host. Supramolecular interactions of FB with GSH have also been corroborated by electrochemical measurements involving two configurations of FB-GSH ensembles on electrodes: (i) an inverted orientation on Au-coated quartz crystal piezoelectrode (Au@SG-FB), with strong thiolate bonding to gold, and (ii) a non-inverted orientation on glassy carbon electrode (GCE@FB-GS), with weak π-π stacking attachment and efficient charge mediation through the ensemble. The formation of a supramolecular ensemble with hydrogen bonding has also been confirmed by quantum mechanical calculations. The discovery of supramolecular FB-GSH ensemble formation enables elucidating the mechanisms of strong RELS responses, changes in UV-Vis absorption spectra, and the electrochemical reactivity. Also, it provides new insights to the understanding of the efficient charge-transfer in redox potential homeostasis

Supramolecular interactions of oxidative stress biomarker glutathione with fluorone black.

Science.gov (United States)

Hepel, Maria; Stobiecka, Magdalena

2018-03-05

Oxidative stress biomarkers, including glutathione (GSH) and related compounds, are involved in a variety of interactions enabling redox potential maintenance in living cells and protection against radicals. Since the oxidative stress is promoting and, in many cases, inducing serious illnesses, monitoring of GSH levels can aid in diagnostics and disease prevention. Herein, we report on the discovery of the formation of a supramolecular ensemble of GSH with fluorone black (9-phenyl fluorone, FB) which is optically active and enables sensitive determination of GSH by resonance elastic light scattering (RELS). We have found that supramolecular interactions of GSH with FB can be probed with spectroscopic, RELS, and electrochemical methods. Our investigations show that RELS intensity for FB solutions increases with GSH concentration while fluorescence emission of FB is not affected, as quenching begins only above 0.8mM GSH. The UV-Vis difference spectra show a positive peak at 383nm and a negative peak at 458nm, indicating a higher-energy absorbing complex in comparison to the non-bonded FB host. Supramolecular interactions of FB with GSH have also been corroborated by electrochemical measurements involving two configurations of FB-GSH ensembles on electrodes: (i) an inverted orientation on Au-coated quartz crystal piezoelectrode (Au@SG-FB), with strong thiolate bonding to gold, and (ii) a non-inverted orientation on glassy carbon electrode (GCE@FB-GS), with weak π-π stacking attachment and efficient charge mediation through the ensemble. The formation of a supramolecular ensemble with hydrogen bonding has also been confirmed by quantum mechanical calculations. The discovery of supramolecular FB-GSH ensemble formation enables elucidating the mechanisms of strong RELS responses, changes in UV-Vis absorption spectra, and the electrochemical reactivity. Also, it provides new insights to the understanding of the efficient charge-transfer in redox potential homeostasis

Effects of xenon insertion into hydrogen bromide. Comparison of the electronic structure of the HBr···CO2 and HXeBr···CO2 complexes using quantum chemical topology methods: electron localization function, atoms in molecules and symmetry adapted perturbation theory.

Science.gov (United States)

Makarewicz, Emilia; Gordon, Agnieszka J; Mierzwicki, Krzysztof; Latajka, Zdzislaw; Berski, Slawomir

2014-06-05

Quantum chemistry methods have been applied to study the influence of the Xe atom inserted into the hydrogen-bromine bond (HBr → HXeBr), particularly on the nature of atomic interactions in the HBr···CO2 and HXeBr···CO2 complexes. Detailed analysis of the nature of chemical bonds has been carried out using topological analysis of the electron localization function, while topological analysis of electron density was used to gain insight into the nature of weak nonbonding interactions. Symmetry-adapted perturbation theory within the orbital approach was applied for greater understanding of the physical contributions to the total interaction energy.

Synthesis of oligonucleotide phosphorodithioates

DEFF Research Database (Denmark)

Beaton, G.; Brill, W. K D; Grandas, A.

1991-01-01

The synthesis of DNA containing sulfur at the two nonbonding internucleotide valencies is reported. Several different routes using either tervalent or pentavalent mononucleotide synthons are described.......The synthesis of DNA containing sulfur at the two nonbonding internucleotide valencies is reported. Several different routes using either tervalent or pentavalent mononucleotide synthons are described....

Highly enantio- and diastereoselective reactions of γ-substituted butenolides through direct vinylogous conjugate additions

KAUST Repository

Zhang, Wen; Tan, Davin; Lee, Richmond; Tong, Guanghu; Chen, Wenchao; Qi, Baojian; Huang, Kuo-Wei; Tan, Choonhong; Jiang, Zhiyong

2012-01-01

The strength of the weak: An L-tert-leucine-derived amine-thiourea catalyst (see scheme, green box) promotes the asymmetric vinylogous conjugate addition reaction between γ-aryl- and alkyl-substituted butenolides with the butenamides and enoates shown. Computational studies show the preference for the observed stereochemistry is a result of favourable weak non-bonding interactions, which stabilize the transition state. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly enantio- and diastereoselective reactions of γ-substituted butenolides through direct vinylogous conjugate additions

KAUST Repository

Zhang, Wen

2012-09-05

The strength of the weak: An L-tert-leucine-derived amine-thiourea catalyst (see scheme, green box) promotes the asymmetric vinylogous conjugate addition reaction between γ-aryl- and alkyl-substituted butenolides with the butenamides and enoates shown. Computational studies show the preference for the observed stereochemistry is a result of favourable weak non-bonding interactions, which stabilize the transition state. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Does an electronic continuum correction improve effective short-range ion-ion interactions in aqueous solution?

Science.gov (United States)

Bruce, Ellen E.; van der Vegt, Nico F. A.

2018-06-01

Non-polarizable force fields for hydrated ions not always accurately describe short-range ion-ion interactions, frequently leading to artificial ion clustering in bulk aqueous solutions. This can be avoided by adjusting the nonbonded anion-cation or cation-water Lennard-Jones parameters. This approach has been successfully applied to different systems, but the parameterization is demanding owing to the necessity of separate investigations of each ion pair. Alternatively, polarization effects may effectively be accounted for using the electronic continuum correction (ECC) of Leontyev et al. [J. Chem. Phys. 119, 8024 (2003)], which involves scaling the ionic charges with the inverse square-root of the water high-frequency dielectric permittivity. ECC has proven to perform well for monovalent salts as well as for divalent salts in water. Its performance, however, for multivalent salts with higher valency remains unexplored. The present work illustrates the applicability of the ECC model to trivalent K3PO4 and divalent K2HPO4 in water. We demonstrate that the ECC models, without additional tuning of force field parameters, provide an accurate description of water-mediated interactions between salt ions. This results in predictions of the osmotic coefficients of aqueous K3PO4 and K2HPO4 solutions in good agreement with experimental data. Analysis of ion pairing thermodynamics in terms of contact ion pair (CIP), solvent-separated ion pair, and double solvent-separated ion pair contributions shows that potassium-phosphate CIP formation is stronger with trivalent than with divalent phosphate ions.

Economic analysis of the hydrogen production by means of the thermo-chemistry process iodine-sulfur with nuclear energy; Analisis economico de la produccion de hidrogeno mediante el proceso termoquimico yodo-azufre con energia nuclear

Energy Technology Data Exchange (ETDEWEB)

Solorzano S, C.; Francois L, J. L., E-mail: cuausos@comunidad.unam.mx [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac No. 8532, Col. Progreso, 62550 Jiutepec, Morelos (Mexico)

2011-11-15

In this work an economic study was realized about a centralized plant of hydrogen production that works by means of a thermo-chemistry cycle of sulfur-iodine and uses heat coming from a nuclear power plant of IV generation, with base in the software -Hydrogen Economic Evaluation Programme- obtained through the IAEA. The sustainable technology that is glimpsed next for the generation of hydrogen is to great scale and based on processes of high temperature coupled to nuclear power plants, being the most important the cycle S-I and the electrolysis to high temperature, for what objective references are presented that can serve as base for the taking of decisions for its introduction in Mexico. After detailing the economic models that uses the software for the calculation of the even cost of hydrogen production and the characteristics, so much of the nuclear plant constituted by fourth generation reactors, as of the plant of hydrogen production, is proposed a -base- case, obtaining a preliminary even cost of hydrogen production with this process; subsequently different cases are studied starting from which are carried out sensibility analysis in several parameters that could rebound in this cost, taking into account that these reactors are still in design and planning stages. (Author)

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

Science.gov (United States)

Arbuznikov, Alexei V; Kaupp, Martin

2012-01-07

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

The use of image analysis for the study of interfacial bonding in solid composite propellant

Directory of Open Access Journals (Sweden)

JASMINA DOSTANIC

2007-10-01

Full Text Available In the framework of this research, the program Image Pro Plus was applied for determining the polymer–oxidizer interactions in HTPB-based composite propellants. In order to improve the interactions, different bonding agents were used, and their efficiency was analyzed. The determination of the quantity, area and radius of non-bonded oxidizer crystals is presented. The position of formed cracks in the specimen and their area has a great influence on the mechanical properties of composite propellant. The preparation of the composite propellant in order to enable the photographing of their structure by means of stereoscopic and metallographic microscopes with the digital camera is also described as well.

PENGEMBANGAN MODEL PEMBELAJARAN KIMIA UNTUK MENINGKATKAN KETERAMPILAN BERPIKIR KRITIS DAN KETERAMPILAN PROSES SAINS SISWA SMU

Directory of Open Access Journals (Sweden)

Yayan Sunarya

2015-01-01

Full Text Available This research develop model of teaching chemistry in senior high school to improve student thinking skill and science process skill. These skills are chosen based on characteristics of thermo-chemistry concept. There are three procedures in this research, i.e.: analysis of thermo-chemistry concepts, development of teaching model, and its implementation. The implementation carried out by the teacher. Subject of this research are 40 students of SMUN Lembang Bandung. The result of model implementation are three kinds of data, consist of teaching-learning activities, assessment test, and interview. Teaching learning activities data are analyzed by subject matter pedagogy method. The result of assessment test analyzed according to assessment type. The interview data support the teachable and accessible of the model. Model implementation by the teacher was not appropriate with the design in classroom activities. On the other hand, students have good concept achievement, but only for few indicator of the thinking skill and science process skill. Key words: thermo-chemistry, teaching model, thinking skill, science process skill

Interactions between an alpha-helix and a beta-sheet. Energetics of alpha/beta packing in proteins.

Science.gov (United States)

Chou, K C; Némethy, G; Rumsey, S; Tuttle, R W; Scheraga, H A

1985-12-05

Conformational energy computations have been carried out to determine the favorable ways of packing a right-handed alpha-helix on a right-twisted antiparallel or parallel beta-sheet. Co-ordinate transformations have been developed to relate the position and orientation of the alpha-helix to the beta-sheet. The packing was investigated for a CH3CO-(L-Ala)16-NHCH3 alpha-helix interacting with five-stranded beta-sheets composed of CH3CO-(L-Val)6-NHCH3 chains. All internal and external variables for both the alpha-helix and the beta-sheet were allowed to change during energy minimization. Four distinct classes of low-energy packing arrangements were found for the alpha-helix interacting with both the parallel and the anti-parallel beta-sheet. The classes differ in the orientation of the axis of the alpha-helix relative to the direction of the strands of the right-twisted beta-sheet. In the class with the most favorable arrangement, the alpha-helix is oriented along the strands of the beta-sheet, as a result of attractive non-bonded side-chain-side-chain interactions along the entire length of the alpha-helix. A class with nearly perpendicular orientation of the helix axis to the strands is also of low energy, because it allows similarly extensive attractive interactions. In the other two classes, the helix is oriented diagonally relative to the strands of the beta-sheet. In one of them, it interacts with the convex surface near the middle of the saddle-shaped twisted beta-sheet. In the other, it is oriented along the concave diagonal of the beta-sheet and, therefore, it interacts only with the corner regions of the sheet, so that this packing is energetically less favorable. The packing arrangements involving an antiparallel and a parallel beta-sheet are generally similar, although the antiparallel beta-sheet has been found to be more flexible. The major features of 163 observed alpha/beta packing arrangements in 37 proteins are accounted for in terms of the computed

Metal-metal bonds involving the f elements. 4. Molecular orbital studies of metal-metal and metal-ligand interactions in dinuclear uranium(V) systems

International Nuclear Information System (INIS)

Cayton, R.H.; Novo-Gradac, K.J.; Bursten, B.E.

1991-01-01

The electronic structures of a series of dinuclear uranium(V) complexes have been investigated using Xα-SW molecular orbital calculations including quasirelativistic corrections. Complexes of the formula U 2 H 10 and U 2 (OH) 10 were used to model the metal-ligand σ and π interactions, respectively, in the known species U 2 (O-i-Pr) 10 . Two basic geometries were investigated: a vertex-sharing bioctahedron with only terminal ligands (D 4h symmetry) and an edge-sharing bioctahedron containing two bridging ligands (D 2h symmetry). The latter geometry, which is that of U 2 (O-i-Pr) 10 , was also examined at U-U bonding and nonbonding distances. The calculations indicate that the U-U interactions are significantly perturbed when H is replaced by OH, owing to strong donation from the OH pπ orbitals into selected U 5f orbitals. The result is a lack of any appreciable U-U interaction for U 2 (OH) 10 in either the D 4h or D 2h geometry. In addition, the overall OH π donation to the U 5f levels is enhanced in the D 2h geometry. The electronic structure of a hypothetical U(V) dimer, Cp 2 U 2 O 4 , was also examined in both bridged and unsupported geometries. The unbridged geometry, like that for U 2 (OH) 10 , suffered from a destabilization of the U-U σ orbital due to ligand π donation and revealed no net U-U bonding. However, the geometry exhibiting two bridging oxo ligands maintains the U-U σ-bonding MO as its lowest energy U 5f orbital. 21 refs., 8 figs., 8 tabs

Adhesion between a rutile surface and a polyimide: a coarse grained molecular dynamics study

Science.gov (United States)

Kumar, Arun; Sudarkodi, V.; Parandekar, Priya V.; Sinha, Nishant K.; Prakash, Om; Nair, Nisanth N.; Basu, Sumit

2018-04-01

Titanium, due to its high strength to weight ratio and polyimides, due to their excellent thermal stability are being increasingly used in aerospace applications. We investigate the bonding between a (110) rutile substrate and a popular commercial polyimide, PMR-15, starting from the known atomic structure of the rutile substrate and the architecture of the polymer. First, the long PMR-15 molecule is divided into four fragments and an all-atom non-bonded forcefield governing the interaction between PMR-15 and a rutile substrate is developed. To this end, parameters of Buckingham potential for interaction between each atom in the fragments and the rutile surface are fitted, so as to ensure that the sum of non-bonded and electrostatic interaction energy between the substrate and a large number of configurations of each fragment, calculated by the quantum mechanical route and obtained from the fitted potential, is closely matched. Further, two coarse grained models of PMR-15 are developed—one for interaction between two coarse grained PMR-15 molecules and another for that between a coarse grained PMR-15 and the rutile substrate. Molecular dynamics simulations with the coarse grained models yields a traction separation law—a very useful tool for conducting continuum level finite element simulations of rutile-PMR-15 joints—governing the normal separation of a PMR-15 block from a flat rutile substrate. Moreover, detailed information about the affinity of various fragments to the substrate are also obtained. In fact, though the separation energy between rutile and PMR-15 turns out to be rather low, our analysis—with merely the molecular architecture of the polyimide as the starting point—provides a scheme for in-silico prediction of adhesion energies for new polyimide formulations.

Determination of Quantum Chemistry Based Force Fields for Molecular Dynamics Simulations of Aromatic Polymers

Science.gov (United States)

Jaffe, Richard; Langhoff, Stephen R. (Technical Monitor)

1995-01-01

Ab initio quantum chemistry calculations for model molecules can be used to parameterize force fields for molecular dynamics simulations of polymers. Emphasis in our research group is on using quantum chemistry-based force fields for molecular dynamics simulations of organic polymers in the melt and glassy states, but the methodology is applicable to simulations of small molecules, multicomponent systems and solutions. Special attention is paid to deriving reliable descriptions of the non-bonded and electrostatic interactions. Several procedures have been developed for deriving and calibrating these parameters. Our force fields for aromatic polyimide simulations will be described. In this application, the intermolecular interactions are the critical factor in determining many properties of the polymer (including its color).

Effect of Non-Equilibrium Surface Thermochemistry in Simulation of Carbon Based Ablators

Science.gov (United States)

Chen, Yih-Kanq; Gokcen, Tahir

2012-01-01

This study demonstrates that coupling of a material thermal response code and a flow solver using non-equilibrium gas/surface interaction model provides time-accurate solutions for the multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal-response and AblatioN Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas mass conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between the material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of nonequilibrium gas/surface interaction chemistry between air and the carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.

Thermochemistry of selected lanthanide and actinide hydroxycarbonates and carbonates

International Nuclear Information System (INIS)

Merli, L.; Fuger, J.

1996-01-01

Lanthanide and actinide carbonates and hydroxycarbonates are, together with the hydroxides, important compounds in the problematics of high level waste disposal, since such and related compounds may appear as solid phases as a result of the interaction of the waste with natural waters. Experimental results on the stability and relationships between these compounds, particularly the hydroxycarbonates, are relatively fragmentary and arise mainly from solubility measurements, and, to a lesser extent, from enthalpy of formation determinations. We report here the enthalpies of formation of a number of well characterized hydroxycarbonates of trivalent lanthanides, namely those of neodymium, samarium, dysprosium, ytterbium, and of americium, as well as that of neodymium sesquicarbonate, using solution calorimetry in acidic media. The obtained values are discussed in the light of literature data on existing solubility and enthalpy of formation of related compounds. Our results have been obtained with a newly conceived sealed calorimeter, briefly described in the paper, in which the CO 2 produced during the dissolution reaction is maintained in solution, thus eliminating the problem of the kinetically slow evolution of the CO 2 (g) from the medium and the irregularities in the associated thermal effect. (orig.)

Benchmark tests and spin adaptation for the particle-particle random phase approximation

Energy Technology Data Exchange (ETDEWEB)

Yang, Yang; Steinmann, Stephan N.; Peng, Degao [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Aggelen, Helen van, E-mail: Helen.VanAggelen@UGent.be [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Department of Inorganic and Physical Chemistry, Ghent University, 9000 Ghent (Belgium); Yang, Weitao, E-mail: Weitao.Yang@duke.edu [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)

2013-11-07

The particle-particle random phase approximation (pp-RPA) provides an approximation to the correlation energy in density functional theory via the adiabatic connection [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)]. It has virtually no delocalization error nor static correlation error for single-bond systems. However, with its formal O(N{sup 6}) scaling, the pp-RPA is computationally expensive. In this paper, we implement a spin-separated and spin-adapted pp-RPA algorithm, which reduces the computational cost by a substantial factor. We then perform benchmark tests on the G2/97 enthalpies of formation database, DBH24 reaction barrier database, and four test sets for non-bonded interactions (HB6/04, CT7/04, DI6/04, and WI9/04). For the G2/97 database, the pp-RPA gives a significantly smaller mean absolute error (8.3 kcal/mol) than the direct particle-hole RPA (ph-RPA) (22.7 kcal/mol). Furthermore, the error in the pp-RPA is nearly constant with the number of atoms in a molecule, while the error in the ph-RPA increases. For chemical reactions involving typical organic closed-shell molecules, pp- and ph-RPA both give accurate reaction energies. Similarly, both RPAs perform well for reaction barriers and nonbonded interactions. These results suggest that the pp-RPA gives reliable energies in chemical applications. The adiabatic connection formalism based on pairing matrix fluctuation is therefore expected to lead to widely applicable and accurate density functionals.

Interaction between poly(vinyl pyrrolidone) PVP and fullerene C60 at the interface in PVP-C60 nanofluids–A spectroscopic study

Science.gov (United States)

Behera, M.; Ram, S.

2018-03-01

Fourier transform infrared and Raman bands shows a discernible enhancement in band intensity of C–H stretching, C=O stretching, C–N stretching, C–H2 bending, and C–H2 in-plane bending in PVP molecules in the presence of C60 molecules. Amplification in intensity is ascribed to microscopic interactions results when a donation of nonbonding electron (n) occurs from a “>N–C=O” entity of PVP into a lowest unoccupied molecular orbital of the C60 molecule in PVP-C60 charge transfer (CT) complex. The C=O stretching band intensity (integrated) Vs C60 content plot exhibits a peak near a critical 13.9 μM C60 value owing to percolation effect. Light emission spectra show that even a small addition of 4.63 μM C60 able to suppress the band intensity by ~23% as a result of an energy loss. The integrated band intensity also decreases through a peak near 13.9 μM when plotted against the C60-content. In correlation to the vibration spectra, the maximum effect observed both in light emission and excitation spectra suggests a percolation effect in the CT complex. Exhibition of percolation threshold in C60-PVP donor-acceptor complex will be helpful in optimizing the photovoltaic properties vital for solar cell applications.

Nonlinear processes in laser heating of chemically active media

Energy Technology Data Exchange (ETDEWEB)

Bunkin, F V; Kirichenko, N A; Luk' yanchuk, B S

1984-08-01

After it had been discovered and in due measure physically comprehended that numerous nontrivial phenomena observed during laser heating of chemically active media are caused primarily by self-stress of laser radiation due to the chemical intertial nonlinearity of the medium, an approach was found for solving problems of laser thermochemistry that is most adequate from the mathematical (and physical) standpoint: the approach of the theory of nonlinear oscillations in point systems and distributed systems. This approach has provided a uniform viewpoint for examination of a variety of phenomena of spatiotemporal self-organization of chemically active media under the effect of laser radiation, qualitative, and in some cases quantitative description of such phenomena as the onset of thermochemical instability, self-oscillations, various spatial structures and the like. Evidently it can be rightly considered that at this juncture a definite stage has been completed in the development of laser thermochemistry marked by the creation of an ideology, method and overall approach to interpretation of the most diverse phenomena under conditions of actual physical experiments. References to the numerous studies that make up the content of this stage of development of laser thermochemistry are to be found in survey papers. 48 references, 10 figures.

X-ray investigations of sulfur-containing fungicides. IV. 4'-[[Benzoyl(4-chlorophenylhydrazono)methyl]sulfonyl]acetanilide and 4'-[[benzoyl(4-methoxyphenylhydrazono)methyl]sulfonyl]acetanilide.

Science.gov (United States)

Wolf, W M

2001-09-01

The conformations of the two approximately isomorphous structures 4'-[[benzoyl(4-chlorophenylhydrazono)methyl]sulfonyl]acetanilide, C(22)H(18)ClN(3)O(4)S, and 4'-[[benzoyl(4-methoxyphenylhydrazono)methyl]sulfonyl]acetanilide, C(23)H(21)N(3)O(5)S, are stabilized by resonance-assisted intramolecular hydrogen bonds linking the hydrazone moieties and sulfonyl groups. The stronger bond is observed in the former compound. The difference in electronic properties between the Cl atom and the methoxy group is too small to significantly alter the non-bonding interactions of the sulfonyl and beta-carbonyl groups.

Thermo-chemistry of nuclear waste glasses: a new approach

International Nuclear Information System (INIS)

Linard, Y.; Neuville, D.R.; Richet, P.

1997-01-01

Understanding of the stability and weathering of glasses used for storing fission products is hampered by a general lack of basic thermochemical information. Models have been setup to predict Gibbs free energies of dissolution of glasses, but ascertaining their accuracy is made difficult by the very lack of reliable experimental data with which model results should be compared. As enthalpies of formation can in principle be determined from usual solution calorimetry experiments, the lack of Gibbs-free energy data for glasses mainly stems from the fact that, as disordered substances, glasses do not obey the third principle and have indeed large configurational entropies. These entropies can be determined from thermochemical measurements only when there exist a congruently melting crystalline compound with the same composition. Using available data, we have calculated the Gibbs-free energies of formation of a series of silicate glasses for which such a calorimetric determination is possible. With these results, we assess the predictions of Paul's model (1977) for calculating Gibbs-free energies of dissolution. As the complex compositions of the borosilicate glasses used for nuclear waste storage prevent determining configurational entropies by calorimetric methods, we point out how these can be determined instead from viscosity measurements. We finally discuss the implications of this approach for modeling of water-glass interactions. (authors)

Drag Reduction by Off-Body Energy Deposition

Data.gov (United States)

National Aeronautics and Space Administration — What are the key technical challenges? Implementation of non-equilibrium thermochemistry; Accurate energy balance; Dynamic impulse measurements at Mach 2 What is...

The X3LYP extended density functional for accurate descriptions of nonbond interactions, spin states, and thermochemical properties

OpenAIRE

Xu, Xin; Goddard, William A., III

2004-01-01

We derive the form for an exact exchange energy density for a density decaying with Gaussian-like behavior at long range. Based on this, we develop the X3LYP (extended hybrid functional combined with Lee-Yang-Parr correlation functional) extended functional for density functional theory to significantly improve the accuracy for hydrogen-bonded and van der Waals complexes while also improving the accuracy in heats of formation, ionization potentials, electron affinities, and total atomic energ...

The X3LYP extended density functional for accurate descriptions of nonbond interactions, spin states, and thermochemical properties

Science.gov (United States)

Xu, Xin; Goddard, William A.

2004-01-01

We derive the form for an exact exchange energy density for a density decaying with Gaussian-like behavior at long range. Based on this, we develop the X3LYP (extended hybrid functional combined with Lee–Yang–Parr correlation functional) extended functional for density functional theory to significantly improve the accuracy for hydrogen-bonded and van der Waals complexes while also improving the accuracy in heats of formation, ionization potentials, electron affinities, and total atomic energies [over the most popular and accurate method, B3LYP (Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional)]. X3LYP also leads to a good description of dipole moments, polarizabilities, and accurate excitation energies from s to d orbitals for transition metal atoms and ions. We suggest that X3LYP will be useful for predicting ligand binding in proteins and DNA. PMID:14981235

Non-bonding interactions and non-covalent delocalization effects play a critical role in the relative stability of group 12 complexes arising from interaction of diethanoldithiocarbamate with the cations of transition metals Zn(II), Cd(II), and Hg(II): a theoretical study.

Science.gov (United States)

Bahrami, Homayoon; Farhadi, Saeed; Siadatnasab, Firouzeh

2016-07-01

The chelating properties of diethanoldithiocarbamate (DEDC) and π-electron flow from the nitrogen atom to the sulfur atom via a plane-delocalized π-orbital system (quasi ring) was studied using a density functional theory method. The molecular structure of DEDC and its complexes with Zn(II), Cd(II), and Hg(II) were also considered. First, the geometries of this ligand and DEDC-Zn(II), DEDC-Cd(II), and DEDC-Hg(II) were optimized, and the formation energies of these complexes were then calculated based on the electronic energy, or sum of electronic energies, with the zero point energy of each species. Formation energies indicated the DEDC-Zn(II) complex as the most stable complex, and DEDC-Cd(II) as the least stable. Structural data showed that the N1-C2 π-bond was localized in the complexes rather than the ligand, and a delocalized π-bond over S7-C2-S8 was also present. The stability of DEDC-Zn(II), DEDC-Cd(II), and DEDC-Hg(II) complexes increased in the presence of the non-specific effects of the solvent (PCM model), and their relative stability did not change. There was π-electron flow or resonance along N1-C2-S7 and along S7-C2-S8 in the ligand. The π-electron flow or resonance along N1-C2-S7 was abolished when the metal interacted with sulfur atoms. Energy belonging to van der Waals interactions and non-covalent delocalization effects between the metal and sulfur atoms of the ligand was calculated for each complex. The results of nucleus-independent chemical shift (NICS) indicated a decreasing trend as Zn(II) Hg(II) for the aromaticity of the quasi-rings. Finally, by ignoring van der Waals interactions and non-covalent delocalization effects between the metal and sulfur atoms of the ligand, the relative stability of the complexes was changed as follows:[Formula: see text] Graphical Abstract Huge electronic cloud localized on Hg(II) in the Hg(II)-DEDC complex.

Thermochemistry of some methoxypyridines

International Nuclear Information System (INIS)

Amaral, Luísa M.P.F.; Ribeiro da Silva, Manuel A.V.

2012-01-01

Highlights: ► Combustion calorimetry was used to determine Δ f H m o (l) of three methoxypyridines. ► Gas-phase Δ f H m o of the studied compounds have been derived. ► The enthalpic increments of substitutions on the pyridine ring is calculated and its internal coherence is discussed. - Abstract: The standard (p o = 0.1 MPa) molar enthalpies of formation, at T = 298.15 K, for the liquids 2-methoxypyridine, 4-methoxypyridine and 2,6-dimethoxypyridine were determined by static bomb combustion calorimetry. The standard molar enthalpies of vaporization, at T = 298.15 K, were measured by Calvet microcalorimetry. The standard (p o = 0.1 MPa) molar enthalpies of formation of the three compounds studied, in the gaseous phase, at T = 298.15 K have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard molar enthalpies of vaporization, yielding ((−42.7 ± 1.9), (−18.2 ± 1.8) and (−233.5 ± 1.8)) kJ · mol −1 , for 2-methoxypyridine, 4-methoxypyridine and 2,6-dimethoxypyridine, respectively.

XLCB: A New Closed-Bomb Data Acquisition and Reduction Program

National Research Council Canada - National Science Library

Homan, Barrie

2001-01-01

.... time data based on given BRs, geometrical form, and propellant thermochemistry. A proposed summary sheet is included to better facilitate the exchange of information between interested parties in the propellant community...

Isothermal, kinetic and thermodynamic studies on basic dye sorption ...

African Journals Online (AJOL)

Isothermal, kinetic and thermodynamic studies on basic dye sorption onto tartaric acid esterified wheat straw. ... African Journal of Biotechnology ... esterified wheat straw (EWS), was originally prepared by solid phase thermochemistry method.

Substrate binding and catalytic mechanism in phospholipase C from Bacillus cereus. a molecular mechanics and molecular dynamics study

DEFF Research Database (Denmark)

da Graça Thrige, D; Buur, J R; Jørgensen, Flemming Steen

1997-01-01

cereus including a docked substrate molecule was subjected to a stepwise molecular mechanics energy minimization. Second, the location of the nucleophilic water molecule in the active site of the fully relaxed enzyme-substrate complex was determined by evaluation of nonbonded interaction energies between...... water molecule was verified during a 100 ps molecular dynamics simulation. During the simulation the substrate undergoes a conformational change, but retains its localization in the active site. The contacts between the enzyme, the substrate, and the nucleophilic water molecule display some fluctuations...... the strong electrostatic interactions in the active site realistically during energy minimization, delocalization of the charges from the three zinc ions was considered. Therefore, quantum mechanics calculations on the zinc ions and the zinc-coordinating residues were carried out prior to the molecular...

Evaluating amber force fields using computed NMR chemical shifts.

Science.gov (United States)

Koes, David R; Vries, John K

2017-10-01

NMR chemical shifts can be computed from molecular dynamics (MD) simulations using a template matching approach and a library of conformers containing chemical shifts generated from ab initio quantum calculations. This approach has potential utility for evaluating the force fields that underlie these simulations. Imperfections in force fields generate flawed atomic coordinates. Chemical shifts obtained from flawed coordinates have errors that can be traced back to these imperfections. We use this approach to evaluate a series of AMBER force fields that have been refined over the course of two decades (ff94, ff96, ff99SB, ff14SB, ff14ipq, and ff15ipq). For each force field a series of MD simulations are carried out for eight model proteins. The calculated chemical shifts for the 1 H, 15 N, and 13 C a atoms are compared with experimental values. Initial evaluations are based on root mean squared (RMS) errors at the protein level. These results are further refined based on secondary structure and the types of atoms involved in nonbonded interactions. The best chemical shift for identifying force field differences is the shift associated with peptide protons. Examination of the model proteins on a residue by residue basis reveals that force field performance is highly dependent on residue position. Examination of the time course of nonbonded interactions at these sites provides explanations for chemical shift differences at the atomic coordinate level. Results show that the newer ff14ipq and ff15ipq force fields developed with the implicitly polarized charge method perform better than the older force fields. © 2017 Wiley Periodicals, Inc.

Pteros: fast and easy to use open-source C++ library for molecular analysis.

Science.gov (United States)

Yesylevskyy, Semen O

2012-07-15

An open-source Pteros library for molecular modeling and analysis of molecular dynamics trajectories for C++ programming language is introduced. Pteros provides a number of routine analysis operations ranging from reading and writing trajectory files and geometry transformations to structural alignment and computation of nonbonded interaction energies. The library features asynchronous trajectory reading and parallel execution of several analysis routines, which greatly simplifies development of computationally intensive trajectory analysis algorithms. Pteros programming interface is very simple and intuitive while the source code is well documented and easily extendible. Pteros is available for free under open-source Artistic License from http://sourceforge.net/projects/pteros/. Copyright © 2012 Wiley Periodicals, Inc.

Achievement report on research and development in the Sunshine Project in fiscal 1976. Research and development of water decomposition by using a hybrid cycle composed of thermo-chemistry and photo-chemistry; 1976 nendo netsukagaku oyobi hikari kagaku hybrid cycle ni yoru mizu bunkai no kenkyu kahatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1977-03-01

This paper describes water decomposition by using a hybrid cycle composed of thermo-chemistry and photo-chemistry. Ferric sulfate and HI are obtained from ferrous sulfate and iodine via photo-chemical reaction. This is an endothermic reaction of 10.8 kcal. Then, the photo-chemically reacted aqueous solution is electrolysed to separate HI, while Fe{sup 3+} (ferric ion) is reduced and converted into Fe{sup 2+} (ferrous ion). Oxygen is generated at this time. Since mixed potential is made from iron oxidation and reduction potential and iodine potential, the electrolytic efficiency is greatly influenced by electrode materials. Ideally, an electrode material that causes only the reduction of Fe{sup 3+}, but not other reactions is preferable. The HI is decomposed into hydrogen and iodine by electrolysis. Research is continuing to acquire hydrogen from HI thermo-chemically. Endothermic reaction heat of 7 to 8 kcal has been obtained in photo-chemical reaction, the heat quantity being close to the theoretical value of 10.8. A result close to the theoretical value may be expected if the electrode material problem is solved. The basic research will be continued for a high possibility of linking the research to a pilot plant in the future. (NEDO)

A Streamline-Upwind Petrov-Galerkin Finite Element Scheme for Non-Ionized Hypersonic Flows in Thermochemical Nonequilibrium

Science.gov (United States)

Kirk, Benjamin S.; Bova, Stephen W.; Bond, Ryan B.

2011-01-01

Presentation topics include background and motivation; physical modeling including governing equations and thermochemistry; finite element formulation; results of inviscid thermal nonequilibrium chemically reacting flow and viscous thermal equilibrium chemical reacting flow; and near-term effort.

The role of the sigma-holes in stability of non-bonded chalcogenide ... benzene interactions: the ground and excited states

Czech Academy of Sciences Publication Activity Database

Sedlák, Robert; Eyrilmez, Saltuk M.; Hobza, Pavel; Nachtigallová, Dana

2018-01-01

Roč. 20, č. 1 (2018), s. 299-306 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA16-16959S Institutional support: RVO:61388963 Keywords : Cambridge Structural Database * correlated molecular calculations * Gaussian basis sets Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

Orbital Kondo effect due to assisted hopping: Superconductivity, mass enhancement in Cooper oxides with apical oxygen

International Nuclear Information System (INIS)

Zawadowski, A.; Penc, K.; Zimanyi, G.

1991-07-01

Orbital Kondo effect is treated in a model, where additional to the conduction band there are localized orbitals with energy not very far from the Fermi energy. If the hopping between the conduction band and the localized heavy orbitals depends on the occupation of the conduction band orbital then orbital Kondo correlation occurs. The assisted hopping vertex is enhanced due to the Coulomb interaction between the heavy orbital and the conduction band. The enhanced hopping results in mass enhancement and attractive interaction in the conduction band. The superconductivity transition temperature is calculated. The models of this type can be applied to the high-T c superconductors where the non-bonding oxygen orbitals of the apical oxygens play the role of heavy orbitals. For an essential range of the parameters the T c obtained is about 100K. (author). 22 refs, 9 figs

Self-adjoint extensions and spectral analysis in the generalized Kratzer problem

International Nuclear Information System (INIS)

Baldiotti, M C; Gitman, D M; Tyutin, I V; Voronov, B L

2011-01-01

We present a mathematically rigorous quantum-mechanical treatment of a one-dimensional non-relativistic motion of a particle in the potential field V(x)=g 1 x -1 +g 2 x -2 , x is an element of R + = [0, ∞). For g 2 >0 and g 1 K (x) and is usually used to describe molecular energy and structure, interactions between different molecules and interactions between non-bonded atoms. We construct all self-adjoint Schroedinger operators with the potential V(x) and represent rigorous solutions of the corresponding spectral problems. Solving the first part of the problem, we use a method of specifying self-adjoint extensions by (asymptotic) self-adjoint boundary conditions. Solving spectral problems, we follow Krein's method of guiding functionals. This work is a continuation of our previous works devoted to the Coulomb, Calogero and Aharonov-Bohm potentials.

Achievement report on research and development in the Sunshine Project in fiscal 1977. Research and development of water decomposition using mixture cycles composed by thermo-chemistry, photo-chemistry and electrochemistry; 1977 nendo netsukagaku, hikari kagaku, denki kagaku konsei cycle ni yoru suibunkai no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1978-03-01

Discussions are being made on manufacture of hydrogen and oxygen from water decomposition using mixture cycles composed by thermo-chemistry, photo-chemistry and electrochemistry using ferrous sulfate and iodine. Photo-chemical reaction produces Fe(OH)SO{sub 4} and HI, but due to difficulty of isolating Fe(OH)SO{sub 4}, photo-chemical reaction that can obtain the compound as Fe{sub 2}(SO{sub 4}){sub 3} was introduced. A method was introduced that can perform HI isolation simultaneously while performing reaction to reduce Fe{sup 3+} and turn it into Fe{sup 2+} (generating oxygen) by means of electrolysing the liquid after the former reaction. The electrolytic process decomposes HI into hydrogen and iodine (discussions on thermo-chemical decomposition is also continued). Since the photo-chemical reaction can cause reverse reaction, discussions were given on the reaction process in order to suppress the reverse reaction and enhance the conversion efficiency. This paper describes the achievements during fiscal 1977. A quantification method was elucidated on individual iodine components so that it can be used for computerized control (measurement of absorbance of I{sub 3}{sup -}) . An electrolytic tank was discussed that decomposes and isolates photo-chemical reaction products before the reverse reaction occurs. Heat diffusion method was also discussed that isolates hydrogen from HI decomposition products. (NEDO)

Organogermanium Chemistry: Germacyclobutanes and digermane Additions to Acetylenes

Energy Technology Data Exchange (ETDEWEB)

Chubb, Andrew Michael [Iowa State Univ., Ames, IA (United States)

2003-01-01

This dissertation comprises two main research projects. The first project, presented in Chapter 1, involves the synthesis and thermochemistry of germacyclobutanes (germetanes). Four new germetanes (spirodigermetane, diallylgermetane, dichlorogermetane, and germacyclobutane) have been synthesized using a modified di-Grignard synthesis. Diallylgermetane is shown to be a useful starting material for obtaining other germetanes, particularly the parent germetane, germacyclobutane. The gas-phase thermochemistries of spirodigermetane, diallylgermetane and germacyclobutane have been explored via pulsed stirred-flow reactor (SFR) studies, showing remarkable differences in decomposition, depending on the substitution at the germanium atom. The second project investigates the thermochemical, photochemical, and catalytic additions of several digermanes to acetylenes. The first examples of thermo- and photochemical additions of Ge-Ge bonds to C{triple_bond}C are demonstrated. Mechanistic investigations are described and comparisons are made to analogous disilane addition reactions, previously studied in their group.

Experimental study on flexural members strengthened with variable bonded pre-stressed CFRP plates

Science.gov (United States)

Zhang, Baojing; Shang, Shouping

2017-08-01

Aiming at the problem that the structural adhesive between CFRP and concrete interface is aging with time and then lost the bond strength, the concept of variable bond prestressed CFRP is put forward. In order to obtain the bearing capacity and failure pattern of the beam strengthened with variable bonding prestressed CFRP plate, three concrete beams of 5.6m long were strengthened by the technology of non-bonding, bonding and variable bonding strengthened with prestressed CFRP plates respectively, the mechanical properties and crack changes of the test beams under three conditions had been compared and analyzed. Test results show that the variable bond strengthened with prestressed CFRP plates with unbonded prestressed CFRP, cracking load was increased by 36%, yield load increased by 4%, the ultimate load increased by 12%; The reinforcement technology of variable bonding prestressed CFRP plate has the characteristics of non-bonding and bonding prestressed CFRP plate reinforcement, which is similar to that of the bonded reinforcement in the early stage of the development of the cracks, then is gradually developing into the non-bonding prestressed reinforcement, the crack spacing and width have the same characteristics as the bonding reinforcement (both crack spacing and width are small), which is more conducive to enhance the durability of the structure.

Electronic structure of the Ga1-xCr xN studied by high-energy photoemission spectroscopy

International Nuclear Information System (INIS)

Kim, J.J.; Makino, H.; Yao, T.; Takata, Y.; Kobayashi, K.; Yamamoto, T.; Hanada, T.; Cho, M.W.; Ikenaga, E.; Yabashi, M.; Miwa, D.; Nishino, Y.; Tamasaku, K.; Ishikawa, T.; Shin, S.

2005-01-01

Valence band spectra of Ga 1-x Cr x N have been investigated by high-energy photoemission spectroscopy at the photon energy of 5.95 keV. Cr doping does introduce a novel electronic structure in the bandgap and causes some change in valence band structure. Based on the first-principle calculation, Cr-associated electronic levels in the bandgap are assigned to nonbonding and antibonding d states while the change of the valence band suggests that the Ga 4s originated states are significantly modified through hybridization with the Cr 3d orbital. The present result evidences that the Ga valence electrons are considerably modified through the interaction with the second nearest-neighbour Cr atoms

Theoretical Probing of Weak Anion-Cation Interactions in Certain Pyridinium-Based Ionic Liquid Ion Pairs and the Application of Molecular Electrostatic Potential in Their Ionic Crystal Density Determination: A Comparative Study Using Density Functional Approach.

Science.gov (United States)

Joseph, Aswathy; Thomas, Vibin Ipe; Żyła, Gaweł; Padmanabhan, A S; Mathew, Suresh

2018-01-11

A comprehensive study on the structure, nature of interaction, and properties of six ionic pairs of 1-butylpyridinium and 1-butyl-4-methylpyridinium cations in combination with tetrafluoroborate (BF 4 - ), chloride (Cl - ), and bromide (Br - ) anions have been carried out using density functional theory (DFT). The anion-cation interaction energy (ΔE int ), thermochemistry values, theoretical band gap, molecular orbital energy order, DFT-based chemical activity descriptors [chemical potential (μ), chemical hardness (η), and electrophilicity index (ω)], and distribution of density of states (DOS) of these ion pairs were investigated. The ascendancy of the -CH 3 substituent at the fourth position of the 1-butylpyridinium cation ring on the values of ΔE int , theoretical band gap and chemical activity descriptors was evaluated. The ΔE int values were negative for all six ion pairs and were highest for Cl - containing ion pairs. The theoretical band gap value after -CH 3 substitution increased from 3.78 to 3.96 eV (for Cl - ) and from 2.74 to 2.88 eV (for Br - ) and decreased from 4.9 to 4.89 eV (for BF 4 - ). Ion pairs of BF 4 - were more susceptible to charge transfer processes as inferred from their significantly high η values and comparatively small difference in ω value after -CH 3 substitution. The change in η and μ values due to the -CH 3 substituent is negligibly small in all cases except for the ion pairs of Cl - . Critical-point (CP) analyses were carried out to investigate the AIM topological parameters at the interionic bond critical points (BCPs). The RDG isosurface analysis indicated that the anion-cation interaction was dominated by strong H cat ···X ani and C cat ···X ani interactions in ion pairs of Cl - and Br - whereas a weak van der Waal's effect dominated in ion pairs of BF 4 - . The molecular electrostatic potential (MESP)-based parameter ΔΔV min measuring the anion-cation interaction strength showed a good linear correlation with

Electroreduction Property and MD Simulation of Nitrobenzene in Ionic Liquid [BMim][Tf2N]/[BMim][BF4

International Nuclear Information System (INIS)

Zeng, Jianping; Zhang, Yinxu; Sun, Ruyao; Chen, Song

2014-01-01

energies between nitrobenzene and different ionic liquids with and without water is little difference. The variation trend of diffusion coefficients in different composite ionic liquids is consistent with that of interaction energies. Analyzing pair correlation functions showed that the bonding and nonbonding interactions are formed between the N, S and O atoms of ionic liquid and the N and O atoms of nitrobenzene. The diffusion is mainly caused by the nonbonding interaction between nitrobenzene and composite ionic liquid, and the interactions with water molecules are obviously greater than that without water. The conclusion is consistent with the experimental results

Electron-induced dry reforming of methane in a temperature-controlled dielectric barrier discharge reactor

KAUST Repository

Zhang, Xuming; Cha, Min

2013-01-01

and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297-773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH4 and CO2, while

Thermochemistry of cyclic acetone peroxides

Energy Technology Data Exchange (ETDEWEB)

Sinditskii, V.P., E-mail: vps@rctu.ru [Mendeleev University of Chemical Technology, 9 Miusskaya Square, 125047 Moscow (Russian Federation); Kolesov, V.I.; Egorshev, V.Yu.; Patrikeev, D.I. [Mendeleev University of Chemical Technology, 9 Miusskaya Square, 125047 Moscow (Russian Federation); Dorofeeva, O.V. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation)

2014-06-01

Highlights: • Old data on DADP and TATP enthalpies of formation have been revised. • Combining Gaussian-4 (G4) theory with an isodesmic reaction scheme allowed calculated enthalpies of formation of TATP and DADP. • Oxygen bomb calorimetry measurements allowed experimental enthalpies of formation of the peroxides. • Both experimental and calculated values show a satisfactory agreement between each other. • The newly obtained enthalpies reasonably account for the observed derivative parameters: heats of decomposition, combustion, and explosion. - Abstract: Two potentially initiating explosive peroxides, diacetonediperoxide (DADP) and triacetonetriperoxide (TATP), were studied in respect to their thermochemical properties. To get the internally self-consistent estimations of gas-phase enthalpy of formation of DADP and TATP, their values were calculated by combining Gaussian-4 (G4) theory with an isodesmic reaction scheme. The energies of combustion (Δ{sub c}U) were measured and the standard enthalpies of formation (Δ{sub f}H{sub 298}{sup °}) of DADP and TATP were derived using the standard enthalpies of formation of the combustion products. The heat of explosion was measured for small low-pressed charges of the peroxides. The obtained enthalpies of formation of DADP and TATP were found to agree well with quantum chemical calculations and reasonably account for the observed derivative parameters: heats of decomposition, combustion, and detonation.

Thermochemistry of rare-earth trifluorides

International Nuclear Information System (INIS)

Kim, K.Y.; Johnson, C.E.

1981-01-01

Using the most recent crystallographic data, the Born-Lande equation was employed to calculate lattice energies of the rare-earth trifluorides. The excellent agreement ( 0 sub(f)(MX 3 ,c,298.15K) can be estimated. The magnitude of the monotonic change of ΔH 0 sub(f)(MX 3 ) for the rare-earth trihalides series (14 4f electrons) is comparable to the energy change between Sc and Ti in which only one 3d electron is added. This energy change is consistent with the chemical evidence that the electrons in the f-orbitals of rare earths contribute negligibly to the bonding. (author)

Thermochemistry of organic azides revisited

International Nuclear Information System (INIS)

Emel'yanenko, Vladimir N.; Algarra, Manuel; Esteves da Silva, Joaquim C.G.; Hierrezuelo, Jesús; López-Romero, Juan M.; Verevkin, Sergey P.

2014-01-01

Highlights: • Pure samples of 4-nitro-phenyl azide, 1-octyl- and 1-decyl-azides were prepared. • Vapour pressures, sublimation and vaporization enthalpies measured by transpiration. • Enthalpy of formation of 1-alkyl azides measured by combustion calorimetry. • Enthalpy of fusion of 4-nitro-phenyl azide measured by DSC. • Experimental gas enthalpies of formation were in agreement with calculated by G4. - Abstract: Highly pure samples of 4-nitro-phenyl azide, 1-octyl azide and 1 decyl-azide were prepared for thermochemical studies. Vapour pressures over the solid and the liquid sample of 4-nitro-phenyl azide have been determined by the transpiration method. The molar enthalpies of vaporization/sublimation for this compound were derived from the temperature dependencies of vapour pressures. The molar enthalpy of fusion of 4-nitro-phenyl azide was measured by DSC. The measured data set for 4-nitro-phenyl azide was successfully checked for internal consistency. Molar enthalpies of vaporization of 1-octyl azide and 1 decyl-azide were measured by transpiration. The molar enthalpies of formation of the liquid 1-octyl azide and 1 decyl-azides were derived from the combustion calorimetry. New experimental results for these organic azides have been used to derive their molar enthalpies of formation in the gas state and for comparison with results from quantum-chemical method G4

Enthalpy of Formation of N ₂ H ₄ (Hydrazine) Revisited

Energy Technology Data Exchange (ETDEWEB)

Feller, David [Department; Bross, David H. [Chemical; Ruscic, Branko [Chemical; Computation

2017-08-02

In order to address the accuracy of the long-standing experimental enthalpy of formation of gas-phase hydrazine, fully confirmed in earlier versions of Active Thermochemical Tables (ATcT), the provenance of that value is re-examined in light of new high-end calculations of the Feller-Peterson-Dixon (FPD) variety. An overly optimistic determination of the vaporization enthalpy of hydrazine, which created an unrealistically strong connection between the gas phase thermochemistry and the calorimetric results defining the thermochemistry of liquid hydrazine was identified as the probable culprit. The new enthalpy of formation of gas-phase hydrazine, based on balancing all available knowledge, was determined to be 111.57 ± 0.47 kJ/mol at 0 K (97.41 kJ/mol at 298.15 K). Close agreement was found between the ATcT (even excluding the latest theoretical result) and FPD enthalpies.

Enthalpy of Formation of N2H4 (Hydrazine) Revisited.

Science.gov (United States)

Feller, David; Bross, David H; Ruscic, Branko

2017-08-17

In order to address the accuracy of the long-standing experimental enthalpy of formation of gas-phase hydrazine, fully confirmed in earlier versions of Active Thermochemical Tables (ATcT), the provenance of that value is re-examined in light of new high-end calculations of the Feller-Peterson-Dixon (FPD) variety. An overly optimistic determination of the vaporization enthalpy of hydrazine, which created an unrealistically strong connection between the gas phase thermochemistry and the calorimetric results defining the thermochemistry of liquid hydrazine, was identified as the probable culprit. The new enthalpy of formation of gas-phase hydrazine, based on balancing all available knowledge, was determined to be 111.57 ± 0.47 kJ/mol at 0 K (97.42 ± 0.47 kJ/mol at 298.15 K). Close agreement was found between the ATcT (even excluding the latest theoretical result) and the FPD enthalpy.

Self-Assembly of Peptides at the Air/Water Interface

Science.gov (United States)

Sayar, Mehmet

2013-03-01

Peptides are commonly used as building blocks for design and development of novel materials with a variety of application areas ranging from drug design to biotechnology. The precise control of molecular architecture and specific nature of the nonbonded interactions among peptides enable aggregates with well defined structural and functional properties. The interaction of peptides with interfaces leads to dramatic changes in their conformational and aggregation behavior. In this talk, I will discuss our research on the interplay of intermolecular forces and influence of interfaces. In the first part the amphiphilic nature of short peptide oligomers and their behavior at the air/water interface will be discussed. The surface driving force and its decomposition will be analyzed. In the second part aggregation of peptides in bulk water and at an interface will be discussed. Different design features which can be tuned to control aggregation behavior will be analyzed.

CHARACTERIZATION OF MONOLITHIC FUEL FOIL PROPERTIES AND BOND STRENGTH

International Nuclear Information System (INIS)

D E Burkes; D D Keiser; D M Wachs; J S Larson; M D Chapple

2007-01-01

Understanding fuel foil mechanical properties, and fuel/cladding bond quality and strength in monolithic plates is an important area of investigation and quantification. Specifically, what constitutes an acceptable monolithic fuel--cladding bond, how are the properties of the bond measured and determined, and what is the impact of fabrication process or change in parameters on the level of bonding? Currently, non-bond areas are quantified employing ultrasonic determinations that are challenging to interpret and understand in terms of irradiation impact. Thus, determining mechanical properties of the fuel foil and what constitutes fuel/cladding non-bonds is essential to successful qualification of monolithic fuel plates. Capabilities and tests related to determination of these properties have been implemented at the INL and are discussed, along with preliminary results

Automated chemical kinetic modeling via hybrid reactive molecular dynamics and quantum chemistry simulations.

Science.gov (United States)

Döntgen, Malte; Schmalz, Felix; Kopp, Wassja A; Kröger, Leif C; Leonhard, Kai

2018-06-13

An automated scheme for obtaining chemical kinetic models from scratch using reactive molecular dynamics and quantum chemistry simulations is presented. This methodology combines the phase space sampling of reactive molecular dynamics with the thermochemistry and kinetics prediction capabilities of quantum mechanics. This scheme provides the NASA polynomial and modified Arrhenius equation parameters for all species and reactions that are observed during the simulation and supplies them in the ChemKin format. The ab initio level of theory for predictions is easily exchangeable and the presently used G3MP2 level of theory is found to reliably reproduce hydrogen and methane oxidation thermochemistry and kinetics data. Chemical kinetic models obtained with this approach are ready-to-use for, e.g., ignition delay time simulations, as shown for hydrogen combustion. The presented extension of the ChemTraYzer approach can be used as a basis for methodologically advancing chemical kinetic modeling schemes and as a black-box approach to generate chemical kinetic models.

DFT-assisted spectroscopic characterization of pyrazosulfuron-ethyl: FT-Raman, FTIR and UV-vis studies of a sulfonyl urea herbicide

Science.gov (United States)

Monicka, J. Clemy; James, C.

2014-10-01

Raman and IR spectra of pyrazosulfuron-ethyl have been reported here, and it is shown that the spectra has been fully interpreted in terms of assigning normal modes to the various spectral features by using density functional theory calculations. The Raman bands observed for PY in solid phase are characteristic for the carbonyl group, Csbnd C, Csbnd H and Nsbnd H stretching and deformation vibrations. The dimer structure of PY was optimized, including the Nsbnd H…N and Csbnd H…O intermolecular interactions. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity and charge delocalization have been analyzed using natural bond orbital analysis. Spectral analysis reveals the substantial effect of non-bonding interaction, conjugation and induction effects in the molecule which in turn influences the bioactivity of the compound. Red shifting of (∼94 cm-1) Nsbnd H stretching band substantiates the presence of strong Nsbnd H…N intramolecular hydrogen bonding in the molecule. The aromatic behavior of pyrimidine and pyrazole ring has been calculated using the HOMA method.

Diagram of states and morphologies of flexible-semiflexible copolymer chains: A Monte Carlo simulation

Energy Technology Data Exchange (ETDEWEB)

Zablotskiy, Sergey V.; Martemyanova, Julia A.; Ivanov, Viktor A. [Faculty of Physics, Moscow State University, Moscow 119991 (Russian Federation); Paul, Wolfgang [Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale) 06099 (Germany)

2016-06-28

A single copolymer chain consisting of multiple flexible (F) and semiflexible (S) blocks has been studied using a continuum bead-spring model by Stochastic Approximation Monte Carlo simulations, which determine the density of states of the model. The only difference between F and S blocks is the intramolecular bending potential, all non-bonded interactions are equal. The state diagrams for this class of models display multiple nematic phases in the collapsed state, characterized through a demixing of the blocks of different stiffness and orientational ordering of the stiff blocks. We observe dumbbell-like morphologies, lamellar phases, and for the larger block lengths also Saturn-like structures with a core of flexible segments and the stiff segments forming a ring around the core.

Diagram of states and morphologies of flexible-semiflexible copolymer chains: A Monte Carlo simulation

International Nuclear Information System (INIS)

Zablotskiy, Sergey V.; Martemyanova, Julia A.; Ivanov, Viktor A.; Paul, Wolfgang

2016-01-01

A single copolymer chain consisting of multiple flexible (F) and semiflexible (S) blocks has been studied using a continuum bead-spring model by Stochastic Approximation Monte Carlo simulations, which determine the density of states of the model. The only difference between F and S blocks is the intramolecular bending potential, all non-bonded interactions are equal. The state diagrams for this class of models display multiple nematic phases in the collapsed state, characterized through a demixing of the blocks of different stiffness and orientational ordering of the stiff blocks. We observe dumbbell-like morphologies, lamellar phases, and for the larger block lengths also Saturn-like structures with a core of flexible segments and the stiff segments forming a ring around the core.

Mesoscopic Simulations of Crosslinked Polymer Networks

Science.gov (United States)

Megariotis, Grigorios; Vogiatzis, Georgios G.; Schneider, Ludwig; Müller, Marcus; Theodorou, Doros N.

2016-08-01

A new methodology and the corresponding C++ code for mesoscopic simulations of elastomers are presented. The test system, crosslinked ds-1’4-polyisoprene’ is simulated with a Brownian Dynamics/kinetic Monte Carlo algorithm as a dense liquid of soft, coarse-grained beads, each representing 5-10 Kuhn segments. From the thermodynamic point of view, the system is described by a Helmholtz free-energy containing contributions from entropic springs between successive beads along a chain, slip-springs representing entanglements between beads on different chains, and non-bonded interactions. The methodology is employed for the calculation of the stress relaxation function from simulations of several microseconds at equilibrium, as well as for the prediction of stress-strain curves of crosslinked polymer networks under deformation.

Achievement report on research and development in the Sunshine Project in fiscal 1979. Research and development on water decomposition by using mixed cycle of thermo-chemistry, photo-chemistry and electrochemistry; 1979 nendo netsukagaku, hikari kagaku, denki kagaku konsei cycle ni yoru mizu bunkai no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-03-01

This paper describes achievements in research and development in the Sunshine Project in fiscal 1979 on water decomposition by using mixed cycle of thermo-chemistry, photo-chemistry and electrochemistry. In research on the light irradiation electrolytic process, with an objective of improving the reaction efficiency, discussions were given by raising light intensity on the irradiated surface as high as 13 times that of the sunlight. The subsequent process is electrolysis of products from photo-chemical reaction, and the product concentration should be high enough to have HI decomposition (hydrogen acquisition) proceed with high efficiency. Experiments were carried out at 0.03 to 0.1M as iodine concentrations (product HI concentration at 3%). A photo-chemical reaction rate of 80% was obtained at light intensity as high as 12 times that of the sunlight, and iodine concentration of 0.07 mM. The efficiency was 15%. Raising temperature causes the reaction rate to decrease, but it can be supplemented by raising the light intensity, where high concentration HI content was obtained. Rate controlling process in the reaction was elucidated from activation energies in the reaction process of each element on the iodine concentrations from 3 to 30 mM used in the photo-chemical reaction. Experiments were performed on HI decomposition (hydrogen acquisition) by using a heat diffusion column. Separation performance in a filled type column was worse than that in an empty type column, which requires future discussions. (NEDO)

Numerical investigation of elastic mechanical properties of graphene structures

International Nuclear Information System (INIS)

Georgantzinos, S.K.; Giannopoulos, G.I.; Anifantis, N.K.

2010-01-01

The computation of the elastic mechanical properties of graphene sheets, nanoribbons and graphite flakes using spring based finite element models is the aim of this paper. Interatomic bonded interactions as well as van der Waals forces between carbon atoms are simulated via the use of appropriate spring elements expressing corresponding potential energies provided by molecular theory. Each layer is idealized as a spring-like structure with carbon atoms represented by nodes while interatomic forces are simulated by translational and torsional springs with linear behavior. The non-bonded van der Waals interactions among atoms which are responsible for keeping the graphene layers together are simulated with the Lennard-Jones potential using appropriate spring elements. Numerical results concerning the Young's modulus, shear modulus and Poisson's ratio for graphene structures are derived in terms of their chilarity, width, length and number of layers. The numerical results from finite element simulations show good agreement with existing numerical values in the open literature.

Self-adjoint extensions and spectral analysis in the generalized Kratzer problem

Energy Technology Data Exchange (ETDEWEB)

Baldiotti, M C; Gitman, D M [Institute of Physics, University of Sao Paulo (Brazil); Tyutin, I V; Voronov, B L, E-mail: baldiott@fma.if.usp.br, E-mail: gitman@dfn.if.usp.br, E-mail: tyutin@lpi.ru, E-mail: voronov@lpi.ru [Lebedev Physical Institute, Moscow (Russian Federation)

2011-06-01

We present a mathematically rigorous quantum-mechanical treatment of a one-dimensional non-relativistic motion of a particle in the potential field V(x)=g{sub 1}x{sup -1}+g{sub 2}x{sup -2}, x is an element of R{sub +} = [0, {infinity}). For g{sub 2}>0 and g{sub 1}<0, the potential is known as the Kratzer potential V{sub K}(x) and is usually used to describe molecular energy and structure, interactions between different molecules and interactions between non-bonded atoms. We construct all self-adjoint Schroedinger operators with the potential V(x) and represent rigorous solutions of the corresponding spectral problems. Solving the first part of the problem, we use a method of specifying self-adjoint extensions by (asymptotic) self-adjoint boundary conditions. Solving spectral problems, we follow Krein's method of guiding functionals. This work is a continuation of our previous works devoted to the Coulomb, Calogero and Aharonov-Bohm potentials.

Radiation Laboratory quarterly report, January 1, 1978--March 31, 1978. NDRL--1877

Energy Technology Data Exchange (ETDEWEB)

1978-04-12

Progress in various studies is reported including studies on: vapor phase structures of inorganic salts; solvated electrons; exchange perturbation theory for many-electron interactions; concept of orbital following; calculation of vibrational form factors in electron impact excitation; limiting behavior of molecule-molecule inelastic collision amplitude at zero momentum transfer; partially diffusion-controlled reactions of isolated pair in condensed media; field-dependent mobilities, T-R energy transfer between electronically excited argon and ground-state CO/sub 2/; dose and dose-rate effects in the radiolysis of liquids; coulombically correlated charge-pair distribution and recombination--the role of non-Gaussian diffusion; non-bonded interactions; pulse radiolysis studies of hydrocarbon radical scavenging processes; oxidation of methoxyhydroxycyclohexadienyl radicals by quinones; reaction of hydroxyl radical with phenol; solvent effects on the lifetimes of photogenerated biradicals; oxidation of amines by triplet duroquinone; production of singlet oxygen from excited states of aliphatic ketones; and measurement of electron spin-lattice relaxation times. (LK)

The gaseous structure of closo-9,12-(SH)(2)-1,2-C2B10H10, a modifier of gold surfaces, as determined using electron diffraction and computational methods

Czech Academy of Sciences Publication Activity Database

Wann, D. A.; Lane, P. D.; Robertson, H. E.; Baše, Tomáš; Hnyk, Drahomír

2013-01-01

Roč. 42, č. 33 (2013), s. 12015-12019 ISSN 1477-9226 R&D Projects: GA ČR GAP208/10/2269 Institutional support: RVO:61388980 Keywords : AB-INITIO CALCULATIONS * GAUSSIAN-BASIS SETS * CORRELATED MOLECULAR CALCULATIONS * THERMOCHEMISTRY * CARBABORANES Subject RIV: CA - Inorganic Chemistry Impact factor: 4.097, year: 2013

Mechanistic Features of the Reactions of Organomagnesium Compounds

DEFF Research Database (Denmark)

Holm, Torkil; Crossland, Ingolf

2000-01-01

1. Introduction. 2. Properties of Grignard reagents. 2.1. Thermochemistry of alkylmagnesium reagents.2.1.1. Heat of formation of Grignard reagents.2.1.2. C-Mg bond dissociation energies.2.1.3. The oxygen-magnesium bond.2.2. Oxidation potentials of Grignard reagents. 2.3. Association equilibria...

Measuring Gas-Phase Basicities of Amino Acids Using an Ion Trap Mass Spectrometer: A Physical Chemistry Laboratory Experiment

Science.gov (United States)

Sunderlin, Lee S.; Ryzhov, Victor; Keller, Lanea M. M.; Gaillard, Elizabeth R.

2005-01-01

An experiment is performed to measure the relative gas-phase basicities of a series of five amino acids to compare the results to literature values. The experiments use the kinetic method for deriving ion thermochemistry and allow students to perform accurate measurements of thermodynamics in a relatively short time.

Calculation of State Specific Rate Coefficients for Non-Equilibrium Hypersonics Applications: from H(Psi) = E(Psi) to k(T) = A *exp(-E(sub a)/RT)

Science.gov (United States)

Jaffe, Richard; Schwenke, David; Chaban, Galina; Panesi, Marco

2014-01-01

Development of High-Fidelity Physics-Based Models to describe hypersonic flight through the atmospheres of Earth and Mars is underway at NASA Ames Research Center. The goal is to construct chemistry models of the collisional and radiative processes that occur in the bow shock and boundary layers of spacecraft during atmospheric entry that are free of empiricism. In this talk I will discuss our philosophy and describe some of our progress. Topics to be covered include thermochemistry, internal energy relaxation, collisional dissociation and radiative emission and absorption. For this work we start by solving the Schrodinger equation to obtain accurate interaction potentials and radiative properties. Then we invoke classical mechanics to compute state-specific heavy particle collision cross sections and reaction rate coefficients. Finally, phenomenological rate coefficients and relaxation times are determined from master equation solutions.

Model analysis of molecular conformations in terms of weak interactions between non bonded atoms

International Nuclear Information System (INIS)

Lombardi, E.

1988-01-01

The aim of the present paper is to establish a reliable basis for the evaluation of stable conformations and rotational barriers for molecules, with possible applications to systems of biological interest. It is proceeded in two steps: first, the effect of chemical environment on orbitals of a given atom is studied for diatomic units, adopting a valence-bond approach and considering, as prototypes, the two simplest series of diatomic molecules with one valence electron each, i.e. the alkali diatomics and the alkali hydrides. In the model, the orbital of the hydrogen atom by a simple (''1S'') gaussian function, the valence orbital of an alkali atom by a function (r 2 -a 2 ) times a simple gaussian (''2S'' gaussian). Dissociation energies D e and equilibrium distances R e are calculated using a scanning procedure. Agreement with experiment is quantitative for the alkali diatomics. For alkali hydrides, good agreement is obtained only if validity of a rule β e R e =constant, for the two atoms separately, is postulated; β e is the characteristic parameter of a ''1S'' gaussian (hydrogen) or a ''2S'' gaussian (alkali atom) function. In a second step, the authors assume validity of the same rule in conformational analysis for any single bonded A-B molecule with A=C, O, N, P, Si, Ge and B=H, or a halogen atom. Gauge β e values for H, F and C are obtained by fitting experimental rotational barriers in C 2 H 6 , C 2 F 6 and C 3 H 8 . Stable conformation of, and barriers to rotation in, ethane-like rotors are determined, applying first-order exchange perturbation theory, in terms of two- and many-center exchange interactions in cluster of non-bonded atoms. Some 60 molecules are analyzed. Agreement with experiments is strikngly good except for a few systematic deviation. Reasons for such discrepancies are discussed

Fundamental aspects of alluminothermic reduction of vanadium pentoxide

International Nuclear Information System (INIS)

Mourao, M.B.; Capocchi, J.D.T.

1982-01-01

The aluminothermic process for the reduction of vanadium pentoxide is considered. Its thermochemistry features are presented, as well as the heat transfer and the rate phenomena concerning such a reaction system. It is pointed out also the effect of the process parameters on the recovery of metallic vanadium. (Author) [pt

High solubility pathway for the carbon dioxide free production of iron.

Science.gov (United States)

Licht, Stuart; Wang, Baohui

2010-10-07

We report a fundamental change in the understanding of iron oxide thermochemistry, opening a facile, new CO(2)-free route to iron production. The resultant process can eliminate a major global source of greenhouse gas emission, producing the staple iron in molten media at high rate and low electrolysis energy.

Extended ion energetics data base for mass spectrometric characterization of energy related pollutants. Final report

International Nuclear Information System (INIS)

Parr, A.C.

1983-01-01

This project funded research at NBS from September, 1982 until November, 1983 and represented a continuation of an effort in precision ion thermochemistry measurements and calculations. The effort was divided into two main areas: laboratory effort using threshold photoelectron-photoion coincidence spectroscopy and a theoretical effort in ion energetics estimation schemes

Generalization of the Gaussian electrostatic model: Extension to arbitrary angular momentum, distributed multipoles, and speedup with reciprocal space methods

Science.gov (United States)

Cisneros, G. Andrés; Piquemal, Jean-Philip; Darden, Thomas A.

2006-11-01

The simulation of biological systems by means of current empirical force fields presents shortcomings due to their lack of accuracy, especially in the description of the nonbonded terms. We have previously introduced a force field based on density fitting termed the Gaussian electrostatic model-0 (GEM-0) J.-P. Piquemal et al. [J. Chem. Phys. 124, 104101 (2006)] that improves the description of the nonbonded interactions. GEM-0 relies on density fitting methodology to reproduce each contribution of the constrained space orbital variation (CSOV) energy decomposition scheme, by expanding the electronic density of the molecule in s-type Gaussian functions centered at specific sites. In the present contribution we extend the Coulomb and exchange components of the force field to auxiliary basis sets of arbitrary angular momentum. Since the basis functions with higher angular momentum have directionality, a reference molecular frame (local frame) formalism is employed for the rotation of the fitted expansion coefficients. In all cases the intermolecular interaction energies are calculated by means of Hermite Gaussian functions using the McMurchie-Davidson [J. Comput. Phys. 26, 218 (1978)] recursion to calculate all the required integrals. Furthermore, the use of Hermite Gaussian functions allows a point multipole decomposition determination at each expansion site. Additionally, the issue of computational speed is investigated by reciprocal space based formalisms which include the particle mesh Ewald (PME) and fast Fourier-Poisson (FFP) methods. Frozen-core (Coulomb and exchange-repulsion) intermolecular interaction results for ten stationary points on the water dimer potential-energy surface, as well as a one-dimensional surface scan for the canonical water dimer, formamide, stacked benzene, and benzene water dimers, are presented. All results show reasonable agreement with the corresponding CSOV calculated reference contributions, around 0.1 and 0.15kcal/mol error for

Theoretical Studies of Elementary Hydrocarbon Species and Their Reactions

Energy Technology Data Exchange (ETDEWEB)

Allen, Wesley D. [University of Georgia, Department of Chemistry and Center for Computational Quantum Chemistry; Schaefer, Henry F. [University of Georgia, Center for Computational Quantum Chemistry

2018-04-08

The research program supported by this DOE grant carried out both methodological development and computational applications of first-principles theoretical chemistry based on quantum mechanical wavefunctions, as directed toward understanding and harnessing the fundamental chemical physics of combustion. To build and refine the world’s database of thermochemistry, spectroscopy, and chemical kinetics, predictive and definitive computational methods are needed that push the envelope of modern electronic structure theory. The application of such methods has been made to gain comprehensive knowledge of the paradigmatic reaction networks by which the n- and i-propyl, t-butyl, and n-butyl radicals are oxidized by O₂. Numerous ROO and QOOH intermediates in these R + O₂ reaction systems have been characterized along with the interconnecting isomerization transition states and the barriers leading to fragmentation. Other combustion-related intermediates have also been studied, including methylsulfinyl radical, cyclobutylidene, and radicals derived from acetaldehyde and vinyl alcohol. Theoretical advances have been achieved and made available to the scientific community by implementation into PSI4, an open-source electronic structure computer package emphasizing automation, advanced libraries, and interoperability. We have pursued the development of universal explicitly correlated methods applicable to general electronic wavefunctions, as well as a framework that allows multideterminant reference functions to be expressed as a single determinant from quasiparticle operators. Finally, a rigorous analytical tool for correlated wavefunctions has been created to elucidate dispersion interactions, which play essential roles in many areas of chemistry, but whose effects are often masked and enigmatic. Our research decomposes and analyzes the coupled-cluster electron correlation energy in molecular systems as a function of interelectronic distance. Concepts

From The Cover: The X3LYP extended density functional for accurate descriptions of nonbond interactions, spin states, and thermochemical properties

Science.gov (United States)

Xu, Xin; Goddard, William A., III

2004-03-01

We derive the form for an exact exchange energy density for a density decaying with Gaussian-like behavior at long range. Based on this, we develop the X3LYP (extended hybrid functional combined with Lee-Yang-Parr correlation functional) extended functional for density functional theory to significantly improve the accuracy for hydrogen-bonded and van der Waals complexes while also improving the accuracy in heats of formation, ionization potentials, electron affinities, and total atomic energies [over the most popular and accurate method, B3LYP (Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional)]. X3LYP also leads to a good description of dipole moments, polarizabilities, and accurate excitation energies from s to d orbitals for transition metal atoms and ions. We suggest that X3LYP will be useful for predicting ligand binding in proteins and DNA.

Mechanical anchorage of FRP tendons – A literature review

DEFF Research Database (Denmark)

Schmidt, Jacob W.; Bennitz, Anders; Täljsten, Björn

2012-01-01

High tensile strength, good resistance to degradation and creep, low weight and, to some extent, the ability to change the modulus of elasticity are some of the advantages of using prestressed, unidirectional FRP (Fibre Reinforced Polymer) tendon systems. Bonded and non-bonded versions of these s......High tensile strength, good resistance to degradation and creep, low weight and, to some extent, the ability to change the modulus of elasticity are some of the advantages of using prestressed, unidirectional FRP (Fibre Reinforced Polymer) tendon systems. Bonded and non-bonded versions...... with such systems. This is especially important in external post-tensioned tendon systems, where the anchorage points are exposed to the full load throughout the life span of the structure. Consequently, there are large requirements related to the long-term capacity and fatigue resistance of such systems. Several...

Calculations for HFIR [High Flux Isotope Reactor] fuel plate non- bonding and fuel segregation uncertainty factors

International Nuclear Information System (INIS)

Kirkpatrick, J.R.

1990-10-01

The effects of non-bonds and of fuel segregation on the package factors of the heat flux in the High Flux Isotope Reactor (HFIR) are examined. The effects of the two defects are examined both separately and together. It is concluded that the peaking factors that are used in the present HFIR thermal analysis code are conservative and thus no changes in the peaking factors are necessary to continue to ensure that HFIR is safe. A study was made of the effect of the non-bond spot diameter on the peaking factor. The conclusion is that the spot can have diameter more than three times the maximum value allowed by the specifications before the peaking factor is greater than the maximum value specified in the present HFIR thermal analysis code. 6 refs., 7 figs., 8 tabs

Energy Diagram for the Catalytic Decomposition of Hydrogen Peroxide

Science.gov (United States)

Tatsuoka, Tomoyuki; Koga, Nobuyoshi

2013-01-01

Drawing a schematic energy diagram for the decomposition of H[subscript 2]O[subscript 2] catalyzed by MnO[subscript 2] through a simple thermometric measurement outlined in this study is intended to integrate students' understanding of thermochemistry and kinetics of chemical reactions. The reaction enthalpy, delta[subscript r]H, is…

Carbon Footprint Calculations: An Application of Chemical Principles

Science.gov (United States)

Treptow, Richard S.

2010-01-01

Topics commonly taught in a general chemistry course can be used to calculate the quantity of carbon dioxide emitted into the atmosphere by various human activities. Each calculation begins with the balanced chemical equation for the reaction that produces the CO[subscript 2] gas. Stoichiometry, thermochemistry, the ideal gas law, and dimensional…

On-surface construction of low-dimensional nanostructures with terminal alkynes: Linking strategies and controlling methodologies

Institute of Scientific and Technical Information of China (English)

Jing Liu; Qi-Wei Chen; Kai Wu

2017-01-01

Bottom-up approach to constructing low-dimensional nanostructures on surfaces with terminal alkynes has drawn great interest because of its potential applications in fabricating advanced functional nanomaterials.The diversity of the achieved products manifests rich chemistry of terminal alkynes and hence careful linking strategies and proper controlling methodologies are required for selective preparations of high-quality target nanoarchitectures.This review summarizes various on-surface linking strategies for terminal alkynes,including non-bonding interactions as well as organometallic and covalent bonds,and presents examples to show effective control of surface assemblies and reactions of terminal alkynes by variations of the precursor structures,substrates and activation modes.Systematic studies of the on-surface linkage of terminal alkynes may help efficient and predictable preparations of surface nanomaterials and further understanding of surface chemistry.

The stereochemistry of the addition of chlorotitanium enolates of N-acyl oxazolidin-2-ones to 5- and 6- membered N-acyliminium ions

Directory of Open Access Journals (Sweden)

Pilli Ronaldo A.

2001-01-01

Full Text Available The stereoselective addition of chiral and achiral titanium enolates derived from the corresponding N-acyl oxazolidin-2-ones to 5- and 6- membered N-acyliminium ions afforded 2-substituted pyrrolidines in moderate to good diastereoisomeric ratio (5:1 to 14:1 while lower diastereoselection was generally observed in the formation of the corresponding 2-substituted piperidines. The stereochemical outcome was found to be modulated by the nature of the cyclic N-acyliminium ion (5- or 6-membered and of its carbamate and by the N-acyl group in the enolate precursor. The preferential lk approach seems to be dictated mainly by the minimization of non-bonding interactions between the N-acyl group in the chlorotitanium (IV enolate and the carbamate and methylene groups in the cyclic N-acyliminium ion.

Alpha complexes in protein structure prediction

DEFF Research Database (Denmark)

Winter, Pawel; Fonseca, Rasmus

2015-01-01

Reducing the computational effort and increasing the accuracy of potential energy functions is of utmost importance in modeling biological systems, for instance in protein structure prediction, docking or design. Evaluating interactions between nonbonded atoms is the bottleneck of such computations......-complexes from scratch for every configuration encountered during the search for the native structure would make this approach hopelessly slow. However, it is argued that kinetic a-complexes can be used to reduce the computational effort of determining the potential energy when "moving" from one configuration...... to a neighboring one. As a consequence, relatively expensive (initial) construction of an a-complex is expected to be compensated by subsequent fast kinetic updates during the search process. Computational results presented in this paper are limited. However, they suggest that the applicability of a...

An Inversion Recovery NMR Kinetics Experiment

Science.gov (United States)

Williams, Travis J.; Kershaw, Allan D.; Li, Vincent; Wu, Xinping

2011-01-01

A convenient laboratory experiment is described in which NMR magnetization transfer by inversion recovery is used to measure the kinetics and thermochemistry of amide bond rotation. The experiment utilizes Varian spectrometers with the VNMRJ 2.3 software, but can be easily adapted to any NMR platform. The procedures and sample data sets in this…

Thermochemistry of dense hydrous magnesium silicates

Science.gov (United States)

Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

1994-01-01

Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

Benchmark thermodynamic properties of methylanisoles: Experimental and theoretical study

International Nuclear Information System (INIS)

Emel’yanenko, Vladimir N.; Zaitseva, Ksenia V.; Agapito, Filipe; Martinho Simões, José A.; Verevkin, Sergey P.

2015-01-01

Highlights: • Thermochemistry of 2-, 3-, and 4-methylanisoles was studied. • Liquid state enthalpies of formation were measured by calorimetry. • Vaporisation enthalpies were derived from by transpiration method. • Ab initio enthalpies of formation are in excellent agreement with experiment. • A new paradigm for obtaining thermochemistry of liquid compounds was suggested. - Abstract: Accurate standard molar enthalpy of formation values in the liquid phase can be obtained by combining high-level quantum chemistry values of gas-phase enthalpies of formation with experimentally determined enthalpies of vaporisation. The procedure is illustrated for 2-, 3-, and 4-methyl-anisoles. Using the W1-F12 and G4 quantum-chemical methods, the gas-phase enthalpies of formation of these compounds at T = 298.15 K were computed. Molar enthalpies of vaporisation for these isomers were measured by the transpiration method. Combining the experimental and the high-level ab initio values, the standard molar enthalpies of formation in the liquid phase for all three isomers were derived and compared with those determined for 2- and 4-methyl-anisoles by using combustion calorimetry

Breaking Rules – Making Bonds

Indian Academy of Sciences (India)

IAS Admin

unusual because it has a pair of non-bonding electrons. So we would classify it ... you would expect the boron to be electron rich with a formal oxidation state of ... Principles of Structure and Reactivity, 4th Edition, Pearson Education, 2008. [3].

Forcefields based molecular modeling on the mechanical and physical properties of emeraldine base polyaniline

NARCIS (Netherlands)

Chen, X.; Yuan, C.A.; Wong, K.Y.; Zhang, G.Q.

2010-01-01

Molecular dynamics (MD) and molecular mechanical (MM) analysis are carried out to provide reliable and accurate model for emeraldine base polyaniline. This study validate the forcefields and model with the physical and mechanical properties of the polyaniline. The temperature effects on non-bond

Cyclopentadiene-mediated hydride transfer from rhodium complexes.

Science.gov (United States)

Pitman, C L; Finster, O N L; Miller, A J M

2016-07-12

Attempts to generate a proposed rhodium hydride catalytic intermediate instead resulted in isolation of (Cp*H)Rh(bpy)Cl (1), a pentamethylcyclopentadiene complex, formed by C-H bond-forming reductive elimination from the fleeting rhodium hydride. The hydride transfer ability of diene 1 was explored through thermochemistry and hydride transfer reactions, including the reduction of NAD(+).

Actinide Sciences at ITN - Basic Studies in Chemistry with Potential Interest for Partitioning, Fuel Fabrication and More

International Nuclear Information System (INIS)

Almeida, M.; Dias, M.; Goncalves, A.P.; Henriques, M.S.; Lopes, E.B.; Pereira, L.C.J.; Santos, I.C.; Verbovytskyy, Y.; Waerenborgh, J.C.; Branco, J.B.; Carretas, J.M.; Cruz, A.; Ferreira, A.C.; Gasche, T.A.; Leal, J.P.; Lopes, G.; Lourenco, C.; Marcalo, J.; Maria, L.; Monteiro, B.; Mora, E.; Pereira, C.C.L.; Paiva, I.

2010-01-01

The current activities in the area of actinide chemistry at ITN, comprising basic research studies in inorganic and organometallic chemistry, catalysis, gas-phase ion chemistry, thermochemistry, and solid state chemistry, are briefly described. Actinide (and lanthanide) chemistry studies at ITN will be pursued connecting basic research with potential applications in nuclear and non-nuclear areas. (authors)

Systematic study of imidazoles inhibiting IDO1 via the integration of molecular mechanics and quantum mechanics calculations.

Science.gov (United States)

Zou, Yi; Wang, Fang; Wang, Yan; Guo, Wenjie; Zhang, Yihua; Xu, Qiang; Lai, Yisheng

2017-05-05

Indoleamine 2,3-dioxygenase 1 (IDO1) is regarded as an attractive target for cancer immunotherapy. To rationalize the detailed interactions between IDO1 and its inhibitors at the atomic level, an integrated computational approach by combining molecular mechanics and quantum mechanics methods was employed in this report. Specifically, the binding modes of 20 inhibitors was initially investigated using the induced fit docking (IFD) protocol, which outperformed other two docking protocols in terms of correctly predicting ligand conformations. Secondly, molecular dynamics (MD) simulations and MM/PBSA free energy calculations were employed to determine the dynamic binding process and crucial residues were confirmed through close contact analysis, hydrogen-bond analysis and binding free energy decomposition calculations. Subsequent quantum mechanics and nonbonding interaction analysis were carried out to provide in-depth explanations on the critical role of those key residues, and Arg231 and 7-propionate of the heme group were major contributors to ligand binding, which lowed a great amount of interaction energy. We anticipate that these findings will be valuable for enzymatic studies and rational drug design. Copyright © 2017. Published by Elsevier Masson SAS.

Design and mechanism of tetrahydrothiophene-based γ-aminobutyric acid aminotransferase inactivators.

Science.gov (United States)

Le, Hoang V; Hawker, Dustin D; Wu, Rui; Doud, Emma; Widom, Julia; Sanishvili, Ruslan; Liu, Dali; Kelleher, Neil L; Silverman, Richard B

2015-04-08

Low levels of γ-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinson's disease, Alzheimer's disease, Huntington's disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the blood-brain barrier and inhibit the activity of γ-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a π-π interaction with Phe-189, and a weak nonbonded S···O═C interaction with Glu-270, thereby inactivating the enzyme.

Design and Mechanism of Tetrahydrothiophene-Based γ-Aminobutyric Acid Aminotransferase Inactivators

Energy Technology Data Exchange (ETDEWEB)

Le, Hoang V. [Departments; Hawker, Dustin D. [Departments; Wu, Rui [Department; Doud, Emma [Departments; Widom, Julia [Departments; Sanishvili, Ruslan [X-ray; Liu, Dali [Department; Kelleher, Neil L. [Departments; Silverman, Richard B. [Departments

2015-03-25

Low levels of gamma-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinsons disease, Alzheimers disease, Huntingtons disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the bloodbrain barrier and inhibit the activity of gamma-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a pi-pi interaction with Phe-189, and a weak nonbonded (SO)-O-...=C interaction with Glu-270, thereby inactivating the enzyme.

Thermodynamic assessment of the Pd−Rh−Ru system using calphad and first-principles methods

Energy Technology Data Exchange (ETDEWEB)

Gossé, S., E-mail: stephane.gosse@cea.fr [DEN-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Dupin, N. [Calcul Thermodynamique, Rue de l' avenir, 63670, Orcet (France); Guéneau, C. [DEN-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Crivello, J.-C.; Joubert, J.-M. [Chimie Métallurgique des Terres Rares, Université Paris Est, ICMPE (UMR 7182), CNRS, UPEC, F-94320, Thiais (France)

2016-06-15

Palladium, rhodium and ruthenium are abundant fission products that form in oxide fuels in nuclear reactors. Under operating conditions, these Platinum-Group Metal (PGM) fission products accumulate in high concentration at the rim of the oxide fuel and mainly precipitate into metallic solid solutions. Their thermochemistry is of significant interest to predict the high temperature chemical interactions between the fuel and the cladding or the possible precipitation of PGM phases in high level nuclear waste glasses. To predict the thermodynamic properties of these PGM fission products, a thermodynamic modeling is being developed on the ternary Pd−Rh−Ru system using the Calphad method. Because experimental thermodynamic data are scarce, Special Quasirandom Structures coupled with Density Functional Theory methods were used to calculate mixing enthalpy data in the solid solutions. The resulting thermodynamic description based on only binary interaction parameters is in good agreement with the few data on the ternary system. - Highlights: • The mixing enthalpy of solid solutions in the Pd−Rh−Ru system was calculated using the DFT and SQS methods. • A thermodynamic assessment of the Pd−Rh−Ru ternary system was performed using the Calphad method. • The extrapolation based on only binary interaction parameters leads to a good agreement with the data on the ternary.

Thermochemistry of paddle wheel MOFs: Cu-HKUST-1 and Zn-HKUST-1.

Science.gov (United States)

Bhunia, Manas K; Hughes, James T; Fettinger, James C; Navrotsky, Alexandra

2013-06-25

Metal-organic framework (MOF) porosity relies upon robust metal-organic bonds to retain structural rigidity upon solvent removal. Both the as-synthesized and activated Cu and Zn polymorphs of HKUST-1 were studied by room temperature acid solution calorimetry. Their enthalpies of formation from dense assemblages (metal oxide (ZnO or CuO), trimesic acid (TMA), and N,N-dimethylformamide (DMF)) were calculated from the calorimetric data. The enthalpy of formation (ΔHf) of the as-synthesized Cu-HKUST-H2O ([Cu3TMA2·3H2O]·5DMF) is -52.70 ± 0.34 kJ per mole of Cu. The ΔHf for Zn-HKUST-DMF ([Zn3TMA2·3DMF]·2DMF) is -54.22 ± 0.57 kJ per mole of Zn. The desolvated Cu-HKUST-dg [Cu3TMA2] has a ΔHf of 16.66 ± 0.51 kJ/mol per mole Cu. The ΔHf for Zn-HKUST-amorph [Zn3TMA2·2DMF] is -3.57 ± 0.21 kJ per mole of Zn. Solvent stabilizes the Cu-HKUST-H2O by -69.4 kJ per mole of Cu and Zn-HKUST-DMF by at least -50.7 kJ per mole of Zn. Such strong chemisorption of solvent is similar in magnitude to the strongly exothermic binding at low coverage for chemisorbed H2O on transition metal oxide nanoparticle surfaces. The strongly exothermic solvent-framework interaction suggests that solvent can play a critical role in obtaining a specific secondary building unit (SBU) topology.

Thermodynamics of a Compressible Maier-Saupe Model Based on the Self-Consistent Field Theory of Wormlike Polymer

Directory of Open Access Journals (Sweden)

Ying Jiang

2017-02-01

Full Text Available This paper presents a theoretical formalism for describing systems of semiflexible polymers, which can have density variations due to finite compressibility and exhibit an isotropic-nematic transition. The molecular architecture of the semiflexible polymers is described by a continuum wormlike-chain model. The non-bonded interactions are described through a functional of two collective variables, the local density and local segmental orientation tensor. In particular, the functional depends quadratically on local density-variations and includes a Maier–Saupe-type term to deal with the orientational ordering. The specified density-dependence stems from a free energy expansion, where the free energy of an isotropic and homogeneous homopolymer melt at some fixed density serves as a reference state. Using this framework, a self-consistent field theory is developed, which produces a Helmholtz free energy that can be used for the calculation of the thermodynamics of the system. The thermodynamic properties are analysed as functions of the compressibility of the model, for values of the compressibility realizable in mesoscopic simulations with soft interactions and in actual polymeric materials.

B-spline tight frame based force matching method

Science.gov (United States)

Yang, Jianbin; Zhu, Guanhua; Tong, Dudu; Lu, Lanyuan; Shen, Zuowei

2018-06-01

In molecular dynamics simulations, compared with popular all-atom force field approaches, coarse-grained (CG) methods are frequently used for the rapid investigations of long time- and length-scale processes in many important biological and soft matter studies. The typical task in coarse-graining is to derive interaction force functions between different CG site types in terms of their distance, bond angle or dihedral angle. In this paper, an ℓ1-regularized least squares model is applied to form the force functions, which makes additional use of the B-spline wavelet frame transform in order to preserve the important features of force functions. The B-spline tight frames system has a simple explicit expression which is useful for representing our force functions. Moreover, the redundancy of the system offers more resilience to the effects of noise and is useful in the case of lossy data. Numerical results for molecular systems involving pairwise non-bonded, three and four-body bonded interactions are obtained to demonstrate the effectiveness of our approach.

Thermochemistry of the solution of β-alanine in (H2O + alcohol) mixtures at 298.15 K

International Nuclear Information System (INIS)

Smirnov, Valeriy I.; Badelin, Valentin G.

2013-01-01

Highlights: • Enthalpies of β-alanine dissolution have been measured in aqueous solution of MeOH, EtOH, 1-PrOH and 2-PrOH. • Measured data were reported as functions of composition of water + alcohol mixtures. • Enthalpy coefficients of pairwise interactions have been analyzed in terms of McMillan–Mayer theory. - Abstract: The enthalpies of the solution of β-alanine in H 2 O + (methanol, ethanol, 1-propanol and 2-propanol) mixtures with alcohol content up to 0.4 mol fractions, have been determined calorimetrically at T = 298.15 K. The standard enthalpies of the solution and transfer of β-alanine from water to aqueous alcohol have been calculated. The effect of structure properties of a mixed solvent on specified enthalpy characteristics of β-alanine is discussed. The enthalpy coefficients of pairwise interactions between β-alanine and alcohol molecules have been computed. It has been found that these coefficients become increasingly positive in methanol, ethanol, 1-propanol, and 2-propanol sequence. A comparative analysis of thermodynamic characteristics of dissolution of β-alanine and D,L-α-alanine in the mixtures studied has been made

Discovery and Early Clinical Evaluation of BMS-605339, a Potent and Orally Efficacious Tripeptidic Acylsulfonamide NS3 Protease Inhibitor for the Treatment of Hepatitis C Virus Infection

Energy Technology Data Exchange (ETDEWEB)

Scola, Paul M.; Wang, Alan Xiangdong; Good, Andrew C.; Sun, Li-Qiang; Combrink, Keith D.; Campbell, Jeffrey A.; Chen, Jie; Tu, Yong; Sin, Ny; Venables, Brian L.; Sit, Sing-Yuen; Chen, Yan; Cocuzza, Anthony; Bilder, Donna M.; D’Andrea, Stanley; Zheng, Barbara; Hewawasam, Piyasena; Ding, Min; Thuring, Jan; Li, Jianqing; Hernandez, Dennis; Yu, Fei; Falk, Paul; Zhai, Guangzhi; Sheaffer, Amy K.; Chen, Chaoqun; Lee, Min S.; Barry, Diana; Knipe, Jay O.; Li, Wenying; Han, Yong-Hae; Jenkins, Susan; Gesenberg, Christoph; Gao, Qi; Sinz, Michael W.; Santone, Kenneth S.; Zvyaga, Tatyana; Rajamani, Ramkumar; Klei, Herbert E.; Colonno, Richard J.; Grasela, Dennis M.; Hughes, Eric; Chien, Caly; Adams, Stephen; Levesque, Paul C.; Li, Danshi; Zhu, Jialong; Meanwell, Nicholas A.; McPhee, Fiona

2014-03-13

The discovery of BMS-605339 (35), a tripeptidic inhibitor of the NS3/4A enzyme, is described. This compound incorporates a cyclopropylacylsulfonamide moiety that was designed to improve the potency of carboxylic acid prototypes through the introduction of favorable nonbonding interactions within the S1' site of the protease. The identification of 35 was enabled through the optimization and balance of critical properties including potency and pharmacokinetics (PK). This was achieved through modulation of the P2* subsite of the inhibitor which identified the isoquinoline ring system as a key template for improving PK properties with further optimization achieved through functionalization. A methoxy moiety at the C6 position of this isoquinoline ring system proved to be optimal with respect to potency and PK, thus providing the clinical compound 35 which demonstrated antiviral activity in HCV-infected patients.

A Strategy to Suppress Phonon Transport in Molecular Junctions Using pi-Stacked Systems

DEFF Research Database (Denmark)

Li, Qian; Strange, Mikkel; Duchemin, Ivan

2017-01-01

to suppress phonon transport in graphene-based molecular junctions preserving high electronic power factor, using nonbonded pi-stackal systems. Using first-principles calculations, we find that the thermal conductance of pi-stacked systems can be reduced by about 95%, compared with that of a covalently bonded...

Organic hydrotrioxides

International Nuclear Information System (INIS)

Shereshovets, Valerii V; Khursan, Sergei L; Komissarov, Vladilen D; Tolstikov, Genrikh A

2001-01-01

The results of studies on the synthesis, structure, thermochemistry and oxidising capacity of organic hydrotrioxides are generalised. Particular emphasis is placed on the analysis of thermal and catalytic decomposition of ROOOH and on generation of free radicals and singlet molecular oxygen. Problems concerning the mechanisms of formation and decomposition of organic hydrotrioxides are also considered. The bibliography includes 154 references.

Relaxation of the chemical bond skin chemisorption size matter ZTP mechanics H2O myths

CERN Document Server

Sun, Chang Q

2014-01-01

The aim of this book is to explore the detectable properties of a material to the parameters of bond and non-bond involved and to clarify the interdependence of various properties. This book is composed of four parts; Part I deals with the formation and relaxation dynamics of bond and non-bond during chemisorptions with uncovering of the correlation among the chemical bond, energy band, and surface potential barrier (3B) during reactions; Part II is focused on the relaxation of bonds between atoms with fewer neighbors than the ideal in bulk with unraveling of the bond order-length-strength (BOLS) correlation mechanism, which clarifies the nature difference between nanostructures and bulk of the same substance; Part III deals with the relaxation dynamics of bond under heating and compressing with revealing of rules on the temperature-resolved elastic and plastic properties of low-dimensional materials; Part IV is focused on the asymmetric relaxation dynamics of the hydrogen bond (O:H-O) and the anomalous behav...

Statistical deconvolution of enthalpic energetic contributions to MHC-peptide binding affinity

Directory of Open Access Journals (Sweden)

Drew Michael GB

2006-03-01

Full Text Available Abstract Background MHC Class I molecules present antigenic peptides to cytotoxic T cells, which forms an integral part of the adaptive immune response. Peptides are bound within a groove formed by the MHC heavy chain. Previous approaches to MHC Class I-peptide binding prediction have largely concentrated on the peptide anchor residues located at the P2 and C-terminus positions. Results A large dataset comprising MHC-peptide structural complexes was created by re-modelling pre-determined x-ray crystallographic structures. Static energetic analysis, following energy minimisation, was performed on the dataset in order to characterise interactions between bound peptides and the MHC Class I molecule, partitioning the interactions within the groove into van der Waals, electrostatic and total non-bonded energy contributions. Conclusion The QSAR techniques of Genetic Function Approximation (GFA and Genetic Partial Least Squares (G/PLS algorithms were used to identify key interactions between the two molecules by comparing the calculated energy values with experimentally-determined BL50 data. Although the peptide termini binding interactions help ensure the stability of the MHC Class I-peptide complex, the central region of the peptide is also important in defining the specificity of the interaction. As thermodynamic studies indicate that peptide association and dissociation may be driven entropically, it may be necessary to incorporate entropic contributions into future calculations.

Computed structure of small benzene clusters

NARCIS (Netherlands)

van de Waal, B.W.

1986-01-01

The structures of small benzene clusters (C6H6)n, n = 2–7, have been calculated employing potential-energy minimization with respect to molecular translational and rotational coordinates, using exp-6-1 non-bonded atom-atom potential functions. The influence of the adopted point-charge model is

A comparison of two instructional methods for drawing Lewis Structures

Science.gov (United States)

Terhune, Kari

Two instructional methods for teaching Lewis structures were compared -- the Direct Octet Rule Method (DORM) and the Commonly Accepted Method (CAM). The DORM gives the number of bonds and the number of nonbonding electrons immediately, while the CAM involves moving electron pairs from nonbonding to bonding electrons, if necessary. The research question was as follows: Will high school chemistry students draw more accurate Lewis structures using the DORM or the CAM? Students in Regular Chemistry 1 (N = 23), Honors Chemistry 1 (N = 51) and Chemistry 2 (N = 15) at an urban high school were the study participants. An identical pretest and posttest was given before and after instruction. Students were given instruction with either the DORM (N = 45), the treatment method, or the CAM (N = 44), the control for two days. After the posttest, 15 students were interviewed, using a semistructured interview process. The pretest/posttest consisted of 23 numerical response questions and 2 to 6 free response questions that were graded using a rubric. A two-way ANOVA showed a significant interaction effect between the groups and the methods, F (1, 70) = 10.960, p = 0.001. Post hoc comparisons using the Bonferroni pairwise comparison showed that Reg Chem 1 students demonstrated larger gain scores when they had been taught the CAM (Mean difference = 3.275, SE = 1.324, p Chemistry 1 students performed better with the DORM, perhaps due to better math skills, enhanced working memory, and better metacognitive skills. Regular Chemistry 1 students performed better with the CAM, perhaps because it is more visual. Teachers may want to use the CAM or a direct-pairing method to introduce the topic and use the DORM in advanced classes when a correct structure is needed quickly.

Nanojets: Electrification, Energetics, Dynamics, Stability and Breakup

Science.gov (United States)

2006-12-31

Indeed, experimental results of field-induced dual-jet formation on droplets, either flowing through a region of high electric field or levitated ...those examined in the simulations. Quantum chemical calculations were carried out to determine the energy-optimal structures and thermochemistry of...described by Perera et al.63 3.2. Quantum chemical methods 3.2.1 Solvated positive ions We have conducted density functional theory (DFT) calculations

Designing "Interaction": How Do Interaction Design Students Address Interaction?

Science.gov (United States)

Karlgren, Klas; Ramberg, Robert; Artman, Henrik

2016-01-01

Interaction design is usually described as being concerned with interactions with and through artifacts but independent of a specific implementation. Design work has been characterized as a conversation between the designer and the situation and this conversation poses a particular challenge for interaction design as interactions can be elusive…

Experimental and theoretical thermochemistry of β-tetralone

International Nuclear Information System (INIS)

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

2008-01-01

The standard (p 0 = 0.1 MPa) molar enthalpy of formation β-tetralone was measured, at T = 298.15 K, by static bomb calorimetry and the standard molar enthalpy of vaporization, at T = 298.15 K, was obtained using Calvet microcalorimetry. These values were used to derive the standard molar enthalpy of formation of the compound in the gaseous phase, at T = 298.15 K, -(75.2 ± 2.5) kJ . mol -1 . Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy function with extended basis sets and more accurate correlated computational techniques of the MCCM/3 suite have been performed

Thermochemistry of ionic liquid heat-transfer fluids

International Nuclear Information System (INIS)

Van Valkenburg, Michael E.; Vaughn, Robert L.; Williams, Margaret; Wilkes, John S.

2005-01-01

Large-scale solar energy collectors intended for electric power generation require a heat-transfer fluid with a set of properties not fully met by currently available commercial materials. Ionic liquids have thermophysical and chemical properties that may be suitable for heat transfer and short heat term storage in power plants using parabolic trough solar collectors. Ionic liquids are salts that are liquid at or near room temperature. Thermal properties important for heat transfer applications are melting point, boiling point, liquidus range, heat capacity, heat of fusion, vapor pressure, and thermal conductivity. Other properties needed to evaluate the usefulness of ionic liquids are density, viscosity and chemical compatibility with certain metals. Three ionic liquids were chosen for study based on their range of solvent properties. The solvent properties correlate with solubility of water in the ionic liquids. The thermal and chemical properties listed above were measured or compiled from the literature. Contamination of the ionic liquids by impurities such as water, halides, and metal ions often affect physical properties. The ionic liquids were analyzed for those impurities, and the impact of the contamination was evaluated by standard addition. The conclusion is that the ionic liquids have some very favorable thermal properties compared to targets established by the Department of Energy for solar collector applications

Thermochemistry of 1,1'-di-n-butyluranocene

International Nuclear Information System (INIS)

Kuznetsov, N.T.; Mitin, V.A.; Kir'yanov, K.V.; Sevast'yanov, V.G.; Bogdanov, V.A.

1987-01-01

Combustion enthalpy, temperature dependence of saturated vapor of uranium 1,1'-di-n-butylcyclooctatetraene (1,1'-di-n-butyluranocene) are determined for the first time and its thermal behaviour is studied using DTA and high temperature spectrophotometry. Melting and thermal decomposition beginning temperatures; melting and vaporization enthalpies; standard formation enthalpies in a condensed and gaseous states; mean dissociation energy of uranium bond to n-butylcyclooctatetraene are calculated according to the data obtained

Thermochemistry of alkali chloride - lanthanoide(III) chlorides

International Nuclear Information System (INIS)

Blachnik, R.; Selle, D.

1979-01-01

The phase diagrams of the mixtures KCl + GdCl 3 resp. DyCl 3 and of CsCl + PrCl 3 (DyCl 3 , ErCl 3 , and YbCl 3 ) were investigated by differential thermal analysis. In the mixtures of lanthanoide(III) chlorides with CsCl resp. KCl three different stoichiometries of the compounds were found, namely A 3 MCl 6 , A 2 MCl 5 , and AM 2 Cl 7 . Debyeograms of the compounds A 3 MCl 6 and AM 2 Cl 7 reveal, that in the case of the latter type all compounds with the same alkali halide have identical structure, whereas in the A 3 MCl 6 compounds three different types of X-ray patterns were observed. The stabilities of the congruently melting compounds can be estimated by comparing the melting point of the compound with the temperature of an extrapolated eutectic point. (author)

Thermochemistry of nuclear fuels in advanced reactors

International Nuclear Information System (INIS)

Agarwal, Renu

2015-01-01

The presence of a large number of elements, accompanied with steep temperature gradient results in dynamic chemistry during nuclear fuel burn-up. Understanding this chemistry is very important for efficient and safe usage of nuclear fuels. The radioactive nature of these fuels puts lot of constraint on regulatory bodies to ensure their accident free operation in the reactors. One of the common aims of advanced fuels is to achieve high burn-up. As burn-up of the fuel increases, chemistry of fission-products becomes increasingly more important. To understand different phenomenon taking place in-pile, many out of-pile experiments are carried out. Extensive studies of thermodynamic properties, phase analysis, thermophysical property evaluation, fuel-fission product clad compatibility are carried out with relevant compounds and simulated fuels (SIMFUEL). All these data are compiled and jointly evaluated using different computational methods to predict fuel behaviour during burn-up. Only when this combined experimental and theoretical information confirms safe operation of the pin, a test pin is prepared and burnt in a test reactor. Every fuel has a different chemistry and different constraints associated with it. In this talk, various thermo-chemical aspects of some of the advanced fuels, mixed carbide, mixed nitride, 'Pu' rich MOX, 'Th' based AHWR fuels and metallic fuels will be discussed. (author)

Molecular Dynamics Simulations of a Linear Nanomotor Driven by Thermophoretic Forces

DEFF Research Database (Denmark)

Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

Molecular Dynamics of a Linear Nanomotor Driven by Thermophoresis Harvey A. Zambrano1, Jens H. Walther1,2 and Richard L. Jaffe3 1Department of Mechanical Engineering, Fluid Mechanics, Technical University of Denmark, DK-2800 Lyngby, Denmark; 2Computational Science and Engineering Laboratory, ETH...... future molecular machines a complete understanding of the friction forces involved on the transport process at the molecular level have to be addressed.18 In this work we perform Molecular Dynamics (MD) simulations using the MD package FASTTUBE19 to study a molecular linear motor consisting of coaxial...... the valence forces within the CNT using Morse, harmonic angle and torsion potentials.19We include a nonbonded carbon-carbon Lennard-Jones potential to describe the vdW interaction between the carbon atoms within the double wall portion of the system. We equilibrate the system at 300K for 0.1 ns, by coupling...

NIST ThermoData Engine: Extension to Solvent Design and Propagation of Uncertainties for Process Simulation

DEFF Research Database (Denmark)

Diky, Vladimir; Chirico, Robert D.; Muzny, Chris

ThermoData Engine (TDE, NIST Standard Reference Databases 103a and 103b) is the first product that implements the concept of Dynamic Data Evaluation in the fields of thermophysics and thermochemistry, which includes maintaining the comprehensive and up-to-date database of experimentally measured ...... uncertainties, curve deviations, and inadequacies of the models. Uncertainty analysis shows relative contributions to the total uncertainty from each component and pair of components....

Impact of SO2 and NO on CO Oxidation under Post-Flame Conditions

DEFF Research Database (Denmark)

Glarborg, Peter; Kubel, Dorte; Dam-Johansen, Kim

1996-01-01

An experimental and theoretical study of the effect of SO2 on moist CO oxidation with and without NO present was carried out under plug-flow conditions. The H/S/O thermochemistry and reaction subset was revised and a chemical kinetic model established that provide a good description of the effect...... of SO2 and NO on CO oxidation as well as the SO2/SO3 ratio in the products....

Class I and Class II restorations of resin composite: an FE analysis of the influence of modulus of elasticity on stresses generated by occlusal loading

DEFF Research Database (Denmark)

Asmussen, Erik; Peutzfeldt, Anne

2008-01-01

the restoration was left nonbonded. The resin composite was modelled with a modulus of elasticity of 5, 10, 15 or 20 GPa and loaded occlusally with 100 N. By means of the soft-ware program ABAQUS the von Mises stresses in enamel and dentin were calculated. RESULTS: In the bonded scenario, the maximum stresses...

A model for phosphate glass topology considering the modifying ion sub-network

DEFF Research Database (Denmark)

Hermansen, Christian; Mauro, J.C.; Yue, Yuanzheng

2014-01-01

In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent with availa......In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent...... with available structural data by NMR and molecular dynamics simulation and dynamic data such glass transition temperature (Tg) and liquid fragility (m). Alkali phosphate glasses are exemplary systems for developing constraint model since the modifying cation network plays an important role besides the primary...... phosphate network. The proposed topological model predicts the changing trend of the Tg and m with increasing alkali oxide content for alkali phosphate glasses, including an anomalous minimum at around 20 mol% alkali oxide content. We find that the minimum in Tg and m is caused by increased connectivity...

Water-Mediated Differential Binding of Strontium and Cesium Cations in Fulvic Acid.

Science.gov (United States)

Sadhu, Biswajit; Sundararajan, Mahesh; Bandyopadhyay, Tusar

2015-08-27

The migration of potentially harmful radionuclides, such as cesium ((137)Cs) and strontium ((90)Sr), in soil is governed by the chemical and biological reactivity of soil components. Soil organic matter (SOM) that can be modeled through fulvic acid (FA) is known to alter the mobility of radionuclide cations, Cs(+) and Sr(2+). Shedding light on the possible interaction mechanisms at the atomic level of these two ions with FA is thus vital to explain their transport behavior and for the design of new ligands for the efficient extraction of radionuclides. Here we have performed molecular dynamics, metadynamics simulations, and density-functional-theory-based calculations to understand the binding mechanism of Sr(2+) and Cs(+) cations with FA. Our studies predict that interaction of Cs(+) to FA is very weak as compared with Sr(2+). While the water-FA interaction is largely responsible for the weak binding of Cs(+) to FA, leading to the outer sphere complexation of the ion with FA, the interaction between Sr(2+) and FA is stronger and thus can surpass the existing secondary nonbonding interaction between coordinated waters and FA, leading to inner sphere complexation of the ion with FA. We also find that entropy plays a dominant role for Cs(+) binding to FA, whereas Sr(2+) binding is an enthalpy-driven process. Our predicted results are found to be in excellent agreement with the available experimental data on complexation of Cs(+) and Sr(2+) with SOM.

Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

Energy Technology Data Exchange (ETDEWEB)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M. (Eindhoven Univ. of Technology (Netherlands))

1990-01-31

ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed.

Molecular dynamics study of water molecule diffusion in oil-paper insulation materials

International Nuclear Information System (INIS)

Liao Ruijin; Zhu Mengzhao; Yang Lijun; Zhou Xin; Gong Chunyan

2011-01-01

Moisture is an important factor that influences the safe operation of transformers. In this study, molecular dynamics was employed to investigate the diffusion behavior of water molecules in the oil-paper insulation materials of transformers. Two oil-cellulose models were built. In the first model, water molecules were initially distributed in oil, and in the second model, water molecules were distributed in cellulose. The non-bonding energies of interaction between water molecules and oil, and between water molecules and cellulose, were calculated by the Dreiding force field. The interaction energy was found to play a dominant role in influencing the equilibrium distribution of water molecules. The radial direction functions of water molecules toward oil and cellulose indicate that the hydrogen bonds between water molecules and cellulose are sufficiently strong to withstand the operating temperature of the transformer. Mean-square displacement analysis of water molecules diffusion suggests that water molecules initially distributed in oil showed anisotropic diffusion; they tended to diffuse toward cellulose. Water molecules initially distributed in cellulose diffused isotropically. This study provides a theoretical contribution for improvements in online monitoring of water in transformers, and for subsequent research on new insulation materials.

Molecular dynamics study of water molecule diffusion in oil-paper insulation materials

Energy Technology Data Exchange (ETDEWEB)

Liao Ruijin [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China); Zhu Mengzhao, E-mail: xiaozhupost@163.co [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China); Yang Lijun; Zhou Xin; Gong Chunyan [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China)

2011-03-01

Moisture is an important factor that influences the safe operation of transformers. In this study, molecular dynamics was employed to investigate the diffusion behavior of water molecules in the oil-paper insulation materials of transformers. Two oil-cellulose models were built. In the first model, water molecules were initially distributed in oil, and in the second model, water molecules were distributed in cellulose. The non-bonding energies of interaction between water molecules and oil, and between water molecules and cellulose, were calculated by the Dreiding force field. The interaction energy was found to play a dominant role in influencing the equilibrium distribution of water molecules. The radial direction functions of water molecules toward oil and cellulose indicate that the hydrogen bonds between water molecules and cellulose are sufficiently strong to withstand the operating temperature of the transformer. Mean-square displacement analysis of water molecules diffusion suggests that water molecules initially distributed in oil showed anisotropic diffusion; they tended to diffuse toward cellulose. Water molecules initially distributed in cellulose diffused isotropically. This study provides a theoretical contribution for improvements in online monitoring of water in transformers, and for subsequent research on new insulation materials.

Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

International Nuclear Information System (INIS)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M.

1990-01-01

ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed

Crystallization in Two Dimensions and a Discrete Gauss-Bonnet Theorem

Science.gov (United States)

De Luca, L.; Friesecke, G.

2018-02-01

We show that the emerging field of discrete differential geometry can be usefully brought to bear on crystallization problems. In particular, we give a simplified proof of the Heitmann-Radin crystallization theorem (Heitmann and Radin in J Stat Phys 22(3):281-287, 1980), which concerns a system of N identical atoms in two dimensions interacting via the idealized pair potential V(r)=+∞ if r1. This is done by endowing the bond graph of a general particle configuration with a suitable notion of discrete curvature, and appealing to a discrete Gauss-Bonnet theorem (Knill in Elem Math 67:1-7, 2012) which, as its continuous cousins, relates the sum/integral of the curvature to topological invariants. This leads to an exact geometric decomposition of the Heitmann-Radin energy into (i) a combinatorial bulk term, (ii) a combinatorial perimeter, (iii) a multiple of the Euler characteristic, and (iv) a natural topological energy contribution due to defects. An analogous exact geometric decomposition is also established for soft potentials such as the Lennard-Jones potential V(r)=r^{-6}-2r^{-12}, where two additional contributions arise, (v) elastic energy and (vi) energy due to non-bonded interactions.

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Science.gov (United States)

Shao, Yihan; Gan, Zhengting; Epifanovsky, Evgeny; Gilbert, Andrew T. B.; Wormit, Michael; Kussmann, Joerg; Lange, Adrian W.; Behn, Andrew; Deng, Jia; Feng, Xintian; Ghosh, Debashree; Goldey, Matthew; Horn, Paul R.; Jacobson, Leif D.; Kaliman, Ilya; Khaliullin, Rustam Z.; Kuś, Tomasz; Landau, Arie; Liu, Jie; Proynov, Emil I.; Rhee, Young Min; Richard, Ryan M.; Rohrdanz, Mary A.; Steele, Ryan P.; Sundstrom, Eric J.; Woodcock, H. Lee, III; Zimmerman, Paul M.; Zuev, Dmitry; Albrecht, Ben; Alguire, Ethan; Austin, Brian; Beran, Gregory J. O.; Bernard, Yves A.; Berquist, Eric; Brandhorst, Kai; Bravaya, Ksenia B.; Brown, Shawn T.; Casanova, David; Chang, Chun-Min; Chen, Yunqing; Chien, Siu Hung; Closser, Kristina D.; Crittenden, Deborah L.; Diedenhofen, Michael; DiStasio, Robert A., Jr.; Do, Hainam; Dutoi, Anthony D.; Edgar, Richard G.; Fatehi, Shervin; Fusti-Molnar, Laszlo; Ghysels, An; Golubeva-Zadorozhnaya, Anna; Gomes, Joseph; Hanson-Heine, Magnus W. D.; Harbach, Philipp H. P.; Hauser, Andreas W.; Hohenstein, Edward G.; Holden, Zachary C.; Jagau, Thomas-C.; Ji, Hyunjun; Kaduk, Benjamin; Khistyaev, Kirill; Kim, Jaehoon; Kim, Jihan; King, Rollin A.; Klunzinger, Phil; Kosenkov, Dmytro; Kowalczyk, Tim; Krauter, Caroline M.; Lao, Ka Un; Laurent, Adèle D.; Lawler, Keith V.; Levchenko, Sergey V.; Lin, Ching Yeh; Liu, Fenglai; Livshits, Ester; Lochan, Rohini C.; Luenser, Arne; Manohar, Prashant; Manzer, Samuel F.; Mao, Shan-Ping; Mardirossian, Narbe; Marenich, Aleksandr V.; Maurer, Simon A.; Mayhall, Nicholas J.; Neuscamman, Eric; Oana, C. Melania; Olivares-Amaya, Roberto; O'Neill, Darragh P.; Parkhill, John A.; Perrine, Trilisa M.; Peverati, Roberto; Prociuk, Alexander; Rehn, Dirk R.; Rosta, Edina; Russ, Nicholas J.; Sharada, Shaama M.; Sharma, Sandeep; Small, David W.; Sodt, Alexander; Stein, Tamar; Stück, David; Su, Yu-Chuan; Thom, Alex J. W.; Tsuchimochi, Takashi; Vanovschi, Vitalii; Vogt, Leslie; Vydrov, Oleg; Wang, Tao; Watson, Mark A.; Wenzel, Jan; White, Alec; Williams, Christopher F.; Yang, Jun; Yeganeh, Sina; Yost, Shane R.; You, Zhi-Qiang; Zhang, Igor Ying; Zhang, Xing; Zhao, Yan; Brooks, Bernard R.; Chan, Garnet K. L.; Chipman, Daniel M.; Cramer, Christopher J.; Goddard, William A., III; Gordon, Mark S.; Hehre, Warren J.; Klamt, Andreas; Schaefer, Henry F., III; Schmidt, Michael W.; Sherrill, C. David; Truhlar, Donald G.; Warshel, Arieh; Xu, Xin; Aspuru-Guzik, Alán; Baer, Roi; Bell, Alexis T.; Besley, Nicholas A.; Chai, Jeng-Da; Dreuw, Andreas; Dunietz, Barry D.; Furlani, Thomas R.; Gwaltney, Steven R.; Hsu, Chao-Ping; Jung, Yousung; Kong, Jing; Lambrecht, Daniel S.; Liang, WanZhen; Ochsenfeld, Christian; Rassolov, Vitaly A.; Slipchenko, Lyudmila V.; Subotnik, Joseph E.; Van Voorhis, Troy; Herbert, John M.; Krylov, Anna I.; Gill, Peter M. W.; Head-Gordon, Martin

2015-01-01

A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.

Theory of microphase separation in homopolymer-oligomer mixtures

Energy Technology Data Exchange (ETDEWEB)

Olemskoi, Alexander [Department of Physical Electronics, Sumy State University, Rimskii-Korsakov St. 2, 40007 Sumy (Ukraine)]. E-mail: alex@ufn.ru; Savelyev, Alexey [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290 (United States)]. E-mail: alexsav@unc.edu

2005-11-01

This work starts with the review of theoretical methods proposed, during past decades, for description of phase behavior in different polymer systems, involving variety of linear polymers (regular and polydisperse block (co)polymers, random polymers) and the polymer systems with non-covalent bonds of different strength. Microphase separation (MS) into different ordered mesophases is known to be the principal property of such systems. It is shown that most of the theoretical approaches proposed for description of the MS are based on the simple random phase approximation (RPA). It turns out, however, that mean field RPA method applied to description of the systems with non-covalent bonds does not provide the whole picture of MS. We show that the problem here arises when one treats both Flory-Huggins non-associated interactions and non-covalent bonds (hydrogen, ionic) within the unified RPA scheme, which is obviously rough for description of the latter type of interactions. Such a theory was developed in a few recent papers for the systems involving weak hydrogen bonds between homopolymer chains and the low molecular weight oligomers (surfactants). However, it leaves some experimental data unaccounted. The purpose of this review is to consider more detailed theory which is able to explain not only all the experimental data for the above systems but also to take into account the strength variation of non-bonding interactions. In particular, we consider the strong ionic interactions, weak hydrogen bonding, and the interactions of intermediate strength between polymer chain and short oligomers within our unifying theory. To develop such a description in a self-consistent way we propose to use a general field theory of stochastic systems. The mesoscopic (lamellar) structure of the periodically alternating layers of stretched homopolymer chains surrounded by perpendicularly oriented oligomeric tails is studied for the systems with both strong (ionic) and weak (hydrogen

Theory of microphase separation in homopolymer-oligomer mixtures

International Nuclear Information System (INIS)

Olemskoi, Alexander; Savelyev, Alexey

2005-01-01

This work starts with the review of theoretical methods proposed, during past decades, for description of phase behavior in different polymer systems, involving variety of linear polymers (regular and polydisperse block (co)polymers, random polymers) and the polymer systems with non-covalent bonds of different strength. Microphase separation (MS) into different ordered mesophases is known to be the principal property of such systems. It is shown that most of the theoretical approaches proposed for description of the MS are based on the simple random phase approximation (RPA). It turns out, however, that mean field RPA method applied to description of the systems with non-covalent bonds does not provide the whole picture of MS. We show that the problem here arises when one treats both Flory-Huggins non-associated interactions and non-covalent bonds (hydrogen, ionic) within the unified RPA scheme, which is obviously rough for description of the latter type of interactions. Such a theory was developed in a few recent papers for the systems involving weak hydrogen bonds between homopolymer chains and the low molecular weight oligomers (surfactants). However, it leaves some experimental data unaccounted. The purpose of this review is to consider more detailed theory which is able to explain not only all the experimental data for the above systems but also to take into account the strength variation of non-bonding interactions. In particular, we consider the strong ionic interactions, weak hydrogen bonding, and the interactions of intermediate strength between polymer chain and short oligomers within our unifying theory. To develop such a description in a self-consistent way we propose to use a general field theory of stochastic systems. The mesoscopic (lamellar) structure of the periodically alternating layers of stretched homopolymer chains surrounded by perpendicularly oriented oligomeric tails is studied for the systems with both strong (ionic) and weak (hydrogen

Application of liquid crystals in thermal nondestructive evaluation

International Nuclear Information System (INIS)

Panakal, J.P.; Mukherjee, S.; Ghosh, J.K.

1983-01-01

In recent years, thermal nondestructive evaluation using Cholestric liquid crystals have found wide applications in industry. Thermography using Cholesteric liquid crystals can be used for detection of nonbonds in metallic composites, hot spots in electronic circuits and preliminary examination of welded pressure vessels. This paper presents the results of experiments on thermography of components using encapsulated liquid crystals. (author)

Local hybrid functionals: An assessment for thermochemical kinetics

International Nuclear Information System (INIS)

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

2007-01-01

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

Structural elucidation, molecular representation and solvent interactions of vitrinite-rich and inertinite-rich South African coals

Science.gov (United States)

van Niekerk, Daniel

the kinetic parameters and it was found that the swelling was governed by relaxation of the coal structure (super-Case II swelling). X-ray computed tomography was conducted confirming anisotropic swelling. The petrographic transitions (maceral-group composition and reflectance) with solvent swelling and extraction were quantified. No changes in the maceral compositions were found, but changes in some coal particles were observed. Random reflectance analysis showed that, for both vitrinite and inertinite, there is a decrease in reflectance values with solvent treatment. Vitrinite reflectograms showed a shift from the dominant reflecting V-types to lower V-types. The inertinite reflectograms exhibited an increase in number of I-types (broadening of reflectrograms). Molecular simulation and visualization approaches to solvent swelling and extraction were performed on the proposed molecular models of vitrinite-rich and inertinite-rich coals. A theoretical extraction yield was determined using solubility parameters and showed agreement with experimental extraction yield trends. Statistical Associating Fluid Theory (SAFT) modeling was explored to test whether this method could predict swelling extent. The predicted swelling trends of SAFT were comparable to that of the experimental swelling results. SAFT was found to be a promising tool for solvent-coal interaction predictions. Partially solvent swollen structures were constructed by the addition of solvent molecules to the original coal molecules using a amorphous building approach. This method showed that coal-coal non-bonding interaction changed with the introduction of solvent. A disruption in the van der Waals interaction energies and a change in hydrogen bond distributions were observed in the swollen coal models and quantified. It was concluded that small changes in coal structure translates to significant changes in solvent interaction behavior. These changes were successfully visualized and simulated using

The intermetallic ThRh5: microstructure and enthalpy increments

International Nuclear Information System (INIS)

Banerjee, Aparna; Joshi, A.R.; Kaity, Santu; Mishra, R.; Roy, S.B.

2013-01-01

Actinide intermetallics are one of the most interesting and important series of compounds. Thermochemistry of these compounds play significant role in understand the nature of bonding in alloys and nuclear fuel performance. In the present paper we report synthesis and characterization of thorium based intermetallic compound ThRh 5 (s) by SEM/EDX technique. The mechanical properties and enthalpy increment as a function of temperature of the alloy has been measured. (author)

Gas-Phase Energetics of Actinide Oxides: An Assessment of Neutral and Cationic Monoxides and Dioxides from Thorium to Curium

Science.gov (United States)

Marçalo, Joaquim; Gibson, John K.

2009-09-01

An assessment of the gas-phase energetics of neutral and singly and doubly charged cationic actinide monoxides and dioxides of thorium, protactinium, uranium, neptunium, plutonium, americium, and curium is presented. A consistent set of metal-oxygen bond dissociation enthalpies, ionization energies, and enthalpies of formation, including new or revised values, is proposed, mainly based on recent experimental data and on correlations with the electronic energetics of the atoms or cations and with condensed-phase thermochemistry.

Runaway reactions. Part 2 Causes of Accidents in selected CSB case histories Part 2

OpenAIRE

GYENES ZSUZSANNA; CARSON PHILLIP

2017-01-01

Part 1 briefly discussed the basic thermochemistry of reactive chemicals, the statistics of accidents involving runaway reactions, and general control measures to minimise risk and mitigate the consequences. The present paper highlights the main causes of major accidents from runaway reactions with illustrative case histories to link theory and practice. It also discusses lessons learned from these accidents, which are very similar in the cases studied. The main causes are management deficien...

The resolution of acyclic P-stereogenic phosphine oxides via the formation of diastereomeric complexes: A case study on ethyl-(2-methylphenyl)-phenylphosphine oxide.

Science.gov (United States)

Bagi, Péter; Varga, Bence; Szilágyi, András; Karaghiosoff, Konstantin; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

2018-04-01

As an example of acyclic P-chiral phosphine oxides, the resolution of ethyl-(2-methylphenyl)-phenylphosphine oxide was elaborated with TADDOL derivatives, or with calcium salts of the tartaric acid derivatives. Besides the study on the resolving agents, several purification methods were developed in order to prepare enantiopure ethyl-(2-methylphenyl)-phenylphosphine oxide. It was found that the title phosphine oxide is a racemic crystal-forming compound, and the recrystallization of the enantiomeric mixtures could be used for the preparation of pure enantiomers. According to our best method, the (R)-ethyl-(2-methylphenyl)-phenylphosphine oxide could be obtained with an enantiomeric excess of 99% and in a yield of 47%. Complete racemization of the enantiomerically enriched phosphine oxide could be accomplished via the formation of a chlorophosphonium salt. Characterization of the crystal structures of the enantiopure phosphine oxide was complemented with that of the diastereomeric intermediate. X-ray analysis revealed the main nonbonding interactions responsible for enantiomeric recognition. © 2018 Wiley Periodicals, Inc.

Interfacial water thickness at inorganic nanoconstructs and biomolecules: Size matters

Energy Technology Data Exchange (ETDEWEB)

Cardellini, Annalisa; Fasano, Matteo; Chiavazzo, Eliodoro; Asinari, Pietro, E-mail: pietro.asinari@polito.it

2016-04-29

Water molecules in the proximity of solid nanostructures influence both the overall properties of liquid and the structure and functionality of solid particles. The study of water dynamics at solid–liquid interfaces has strong implications in energy, environmental and biomedical fields. This article focuses on the hydration layer properties in the proximity of Carbon Nanotubes (CNTs) and biomolecules (proteins, polypeptides and amino acids). Here we show a quantitative relation between the solid surface extension and the characteristic length of water nanolayer (δ), which is confined at solid–liquid interfaces. Specifically, the size dependence is attributed to the limited superposition of nonbonded interactions in case of small molecules. These results may facilitate the design of novel energy or biomedical colloidal nanosuspensions, and a more fundamental understanding of biomolecular processes influenced by nanoscale water dynamics. - Highlights: • Properties of the water hydration layer are investigated. • New relation between extension of solid size and hydration layer established. • Possible impact on rational design of nanosuspensions.

Optimizing the Performance of Reactive Molecular Dynamics Simulations for Multi-core Architectures

Energy Technology Data Exchange (ETDEWEB)

Aktulga, Hasan Metin [Michigan State Univ., East Lansing, MI (United States); Coffman, Paul [Argonne National Lab. (ANL), Argonne, IL (United States); Shan, Tzu-Ray [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knight, Chris [Argonne National Lab. (ANL), Argonne, IL (United States); Jiang, Wei [Argonne National Lab. (ANL), Argonne, IL (United States)

2015-12-01

Hybrid parallelism allows high performance computing applications to better leverage the increasing on-node parallelism of modern supercomputers. In this paper, we present a hybrid parallel implementation of the widely used LAMMPS/ReaxC package, where the construction of bonded and nonbonded lists and evaluation of complex ReaxFF interactions are implemented efficiently using OpenMP parallelism. Additionally, the performance of the QEq charge equilibration scheme is examined and a dual-solver is implemented. We present the performance of the resulting ReaxC-OMP package on a state-of-the-art multi-core architecture Mira, an IBM BlueGene/Q supercomputer. For system sizes ranging from 32 thousand to 16.6 million particles, speedups in the range of 1.5-4.5x are observed using the new ReaxC-OMP software. Sustained performance improvements have been observed for up to 262,144 cores (1,048,576 processes) of Mira with a weak scaling efficiency of 91.5% in larger simulations containing 16.6 million particles.

Sorption Energy Maps of Clay Mineral Surfaces

International Nuclear Information System (INIS)

Cygan, Randall T.; Kirkpatrick, R. James

1999-01-01

A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation

Parallel Atomistic Simulations

Energy Technology Data Exchange (ETDEWEB)

HEFFELFINGER,GRANT S.

2000-01-18

Algorithms developed to enable the use of atomistic molecular simulation methods with parallel computers are reviewed. Methods appropriate for bonded as well as non-bonded (and charged) interactions are included. While strategies for obtaining parallel molecular simulations have been developed for the full variety of atomistic simulation methods, molecular dynamics and Monte Carlo have received the most attention. Three main types of parallel molecular dynamics simulations have been developed, the replicated data decomposition, the spatial decomposition, and the force decomposition. For Monte Carlo simulations, parallel algorithms have been developed which can be divided into two categories, those which require a modified Markov chain and those which do not. Parallel algorithms developed for other simulation methods such as Gibbs ensemble Monte Carlo, grand canonical molecular dynamics, and Monte Carlo methods for protein structure determination are also reviewed and issues such as how to measure parallel efficiency, especially in the case of parallel Monte Carlo algorithms with modified Markov chains are discussed.

Molecular Dynamics Modeling of the Effect of Axial and Transverse Compression on the Residual Tensile Properties of Ballistic Fiber

Directory of Open Access Journals (Sweden)

Sanjib C. Chowdhury

2017-02-01

Full Text Available Ballistic impact induces multiaxial loading on Kevlar® and polyethylene fibers used in protective armor systems. The influence of multiaxial loading on fiber failure is not well understood. Experiments show reduction in the tensile strength of these fibers after axial and transverse compression. In this paper, we use molecular dynamics (MD simulations to explain and develop a fundamental understanding of this experimental observation since the property reduction mechanism evolves from the atomistic level. An all-atom MD method is used where bonded and non-bonded atomic interactions are described through a state-of-the-art reactive force field. Monotonic tension simulations in three principal directions of the models are conducted to determine the anisotropic elastic and strength properties. Then the models are subjected to multi-axial loads—axial compression, followed by axial tension and transverse compression, followed by axial tension. MD simulation results indicate that pre-compression distorts the crystal structure, inducing preloading of the covalent bonds and resulting in lower tensile properties.

pMD-Membrane: A Method for Ligand Binding Site Identification in Membrane-Bound Proteins.

Directory of Open Access Journals (Sweden)

Priyanka Prakash

2015-10-01

Full Text Available Probe-based or mixed solvent molecular dynamics simulation is a useful approach for the identification and characterization of druggable sites in drug targets. However, thus far the method has been applied only to soluble proteins. A major reason for this is the potential effect of the probe molecules on membrane structure. We have developed a technique to overcome this limitation that entails modification of force field parameters to reduce a few pairwise non-bonded interactions between selected atoms of the probe molecules and bilayer lipids. We used the resulting technique, termed pMD-membrane, to identify allosteric ligand binding sites on the G12D and G13D oncogenic mutants of the K-Ras protein bound to a negatively charged lipid bilayer. In addition, we show that differences in probe occupancy can be used to quantify changes in the accessibility of druggable sites due to conformational changes induced by membrane binding or mutation.

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

Science.gov (United States)

Chai, Jeng-Da

2017-01-28

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

Approaching the basis set limit for DFT calculations using an environment-adapted minimal basis with perturbation theory: Formulation, proof of concept, and a pilot implementation

International Nuclear Information System (INIS)

Mao, Yuezhi; Horn, Paul R.; Mardirossian, Narbe; Head-Gordon, Teresa; Skylaris, Chris-Kriton; Head-Gordon, Martin

2016-01-01

Recently developed density functionals have good accuracy for both thermochemistry (TC) and non-covalent interactions (NC) if very large atomic orbital basis sets are used. To approach the basis set limit with potentially lower computational cost, a new self-consistent field (SCF) scheme is presented that employs minimal adaptive basis (MAB) functions. The MAB functions are optimized on each atomic site by minimizing a surrogate function. High accuracy is obtained by applying a perturbative correction (PC) to the MAB calculation, similar to dual basis approaches. Compared to exact SCF results, using this MAB-SCF (PC) approach with the same large target basis set produces <0.15 kcal/mol root-mean-square deviations for most of the tested TC datasets, and <0.1 kcal/mol for most of the NC datasets. The performance of density functionals near the basis set limit can be even better reproduced. With further improvement to its implementation, MAB-SCF (PC) is a promising lower-cost substitute for conventional large-basis calculations as a method to approach the basis set limit of modern density functionals.

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

Science.gov (United States)

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

2015-01-13

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

Exploration of zeroth-order wavefunctions and energies as a first step toward intramolecular symmetry-adapted perturbation theory

Science.gov (United States)

Gonthier, Jérôme F.; Corminboeuf, Clémence

2014-04-01

Non-covalent interactions occur between and within all molecules and have a profound impact on structural and electronic phenomena in chemistry, biology, and material science. Understanding the nature of inter- and intramolecular interactions is essential not only for establishing the relation between structure and properties, but also for facilitating the rational design of molecules with targeted properties. These objectives have motivated the development of theoretical schemes decomposing intermolecular interactions into physically meaningful terms. Among the various existing energy decomposition schemes, Symmetry-Adapted Perturbation Theory (SAPT) is one of the most successful as it naturally decomposes the interaction energy into physical and intuitive terms. Unfortunately, analogous approaches for intramolecular energies are theoretically highly challenging and virtually nonexistent. Here, we introduce a zeroth-order wavefunction and energy, which represent the first step toward the development of an intramolecular variant of the SAPT formalism. The proposed energy expression is based on the Chemical Hamiltonian Approach (CHA), which relies upon an asymmetric interpretation of the electronic integrals. The orbitals are optimized with a non-hermitian Fock matrix based on two variants: one using orbitals strictly localized on individual fragments and the other using canonical (delocalized) orbitals. The zeroth-order wavefunction and energy expression are validated on a series of prototypical systems. The computed intramolecular interaction energies demonstrate that our approach combining the CHA with strictly localized orbitals achieves reasonable interaction energies and basis set dependence in addition to producing intuitive energy trends. Our zeroth-order wavefunction is the primary step fundamental to the derivation of any perturbation theory correction, which has the potential to truly transform our understanding and quantification of non-bonded

Exploration of zeroth-order wavefunctions and energies as a first step toward intramolecular symmetry-adapted perturbation theory

International Nuclear Information System (INIS)

Gonthier, Jérôme F.; Corminboeuf, Clémence

2014-01-01

Non-covalent interactions occur between and within all molecules and have a profound impact on structural and electronic phenomena in chemistry, biology, and material science. Understanding the nature of inter- and intramolecular interactions is essential not only for establishing the relation between structure and properties, but also for facilitating the rational design of molecules with targeted properties. These objectives have motivated the development of theoretical schemes decomposing intermolecular interactions into physically meaningful terms. Among the various existing energy decomposition schemes, Symmetry-Adapted Perturbation Theory (SAPT) is one of the most successful as it naturally decomposes the interaction energy into physical and intuitive terms. Unfortunately, analogous approaches for intramolecular energies are theoretically highly challenging and virtually nonexistent. Here, we introduce a zeroth-order wavefunction and energy, which represent the first step toward the development of an intramolecular variant of the SAPT formalism. The proposed energy expression is based on the Chemical Hamiltonian Approach (CHA), which relies upon an asymmetric interpretation of the electronic integrals. The orbitals are optimized with a non-hermitian Fock matrix based on two variants: one using orbitals strictly localized on individual fragments and the other using canonical (delocalized) orbitals. The zeroth-order wavefunction and energy expression are validated on a series of prototypical systems. The computed intramolecular interaction energies demonstrate that our approach combining the CHA with strictly localized orbitals achieves reasonable interaction energies and basis set dependence in addition to producing intuitive energy trends. Our zeroth-order wavefunction is the primary step fundamental to the derivation of any perturbation theory correction, which has the potential to truly transform our understanding and quantification of non-bonded

An Inversion Recovery NMR Kinetics Experiment

OpenAIRE

Williams, Travis J.; Kershaw, Allan D.; Li, Vincent; Wu, Xinping

2011-01-01

A convenient laboratory experiment is described in which NMR magnetization transfer by inversion recovery is used to measure the kinetics and thermochemistry of amide bond rotation. The experiment utilizes Varian spectrometers with the VNMRJ 2.3 software, but can be easily adapted to any NMR platform. The procedures and sample data sets in this article will enable instructors to use inversion recovery as a laboratory activity in applied NMR classes and provide research students with a conveni...

Julius Thomsen and 19th-century speculations on the complexity of atoms

DEFF Research Database (Denmark)

Kragh, Helge

1982-01-01

In the history of chemistry, the Danish chemist Julius Thomsen (1826-1909) is best known for his contributions to thermochemistry. Throughout his life, he was a pronounced atomist and a tireless advocate of neo-Proutian views as to the constitution of matter. On many occasions, especially in his ...... as to the constitution of matter, the periodic system and the noble gases, may be seen as typical of this vigorous trend in fin de si cle chemistry....

Current programmes of Metallurgy Division (1991)

International Nuclear Information System (INIS)

1991-01-01

Current research and development programmes of the Metallurgy Division are listed under the headings: 1)Thrust Areas, 2)High Temperature Materials Section, 3)Chemical Metallurgy Section, 4)Metallurgical Thermochemistry Section, 5)Physical Metallurgy Section, 6)Mechanical Metallurgy Section, 7)Corrosion Metallurgy Section, 8)Electrochemical Science and Technology Section, 9)Ceramics Section, and 10)Fabrication and Maintenance Group. A list of equipment in the Division and a list of sciientific personnel of the Division are also given. (M.G.B.)

Effects of collision energy and vibrational excitation of CH3+ cations on its reactivity with hydrocarbons: But-2-yne CH3CCCH3 as reagent partner

Czech Academy of Sciences Publication Activity Database

Cernuto, A.; Lopes, A.; Romanzin, C.; de Miranda, B. C.; Ascenzi, D.; Tosi, P.; Tonachini, G.; Maranzana, A.; Polášek, Miroslav; Žabka, Ján; Alcaraz, Ch.

2017-01-01

Roč. 147, č. 15 (2017), č. článku 154302. ISSN 0021-9606 R&D Projects: GA MŠk(CZ) LD14024; GA ČR(CZ) GA17-14200S Grant - others:COST(XE) TD1308; COST(XE) CM1401 Institutional support: RVO:61388955 Keywords : titans upper-atmosphere * dielectric barrier discharge * main-group thermochemistry * ion-molecule reactions * basis-set convergence Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.965, year: 2016

The role of pressure in rubber elasticity.

Science.gov (United States)

Bower, A F; Weiner, J H

2004-06-22

We describe a series of molecular dynamics computations that reveal an intimate connection at the atomic scale between difference stress (which resists stretches) and pressure (which resists volume changes) in an idealized elastomer, in contrast to the classical theory of rubber elasticity. Our simulations idealize the elastomer as a "pearl necklace," in which the covalent bonds are stiff linear springs, while nonbonded atoms interact through a Lennard-Jones potential with energy epsilon(LJ) and radius sigma(LJ). We calculate the difference stress t(11)-(t(22)+t(33))/2 and mean stress (t(11)+t(22)+t(33))/3 induced by a constant volume extension in the x(1) direction, as a function of temperature T and reduced density rho(*)=Nsigma(IJ) (3)/nu. Here, N is the number of atoms in the simulation cell and nu is the cell volume. Results show that for rho(*)rubber elasticity, which neglects nonbonded interactions. However, data presented by van Krevelen [Properties of Polymers, 3rd ed. (Elsevier, Amsterdam, 1990), p. 79] indicate that rubber at standard conditions corresponds to rho(*)=1.2. For rho(*)>1, the system is entropic for kT/epsilon(LJ)>2, but at lower temperatures the difference stress contains an additional energy component, which increases as rho(*) increases and temperature decreases. Finally, the model exhibits a glass transition for rho(*)=1.2 and kT/epsilon(LJ) approximately 2. The atomic-scale processes responsible for generating stress are explored in detail. Simulations demonstrate that the repulsive portion of the Lennard-Jones potential provides a contribution sigma(nbr)>0 to the difference stress, the attractive portion provides sigma(nba) approximately 0, while the covalent bonds provide sigma(b)nbr)0, and Pi(b)nbr)=-APi(nbr)P(2)(theta(b)), sigma(b)=BPi(b)P(2)(theta(b)), where P(2)(theta(b)) is a measure of the anisotropy of the orientation of the covalent bonds, and A and B are coefficients that depend weakly on rho(*) and temperature. For high

Experimental and computational thermochemistry of the dihydroxypyridine isomers

International Nuclear Information System (INIS)

Morais, Victor M.F.; Miranda, Margarida S.; Matos, M. Agostinha R.

2006-01-01

The standard (p 0 = 0.1 MPa) molar enthalpy of formation for crystalline 2,3-dihydroxypyridine was measured, at T = 298.15 K, by static bomb calorimetry and the standard molar enthalpy of sublimation, at T 298.15 K, was obtained using Calvet microcalorimetry. These values were used to derive the standard molar enthalpy of formation of 2,3-dihydroxypyridine in gaseous phase, at T = 298.15 K, -(263.9 ± 4.6) kJ . mol -1 . Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional with extended basis sets have been performed for all dihydroxypyridine isomers to determine the thermochemical order of stability of these systems. The agreement between experiment and theory for the 2,3-dihydroxypyridine isomer gives confidence to the estimates of the enthalpies of formation concerning the other five isomers. It is found that the enthalpic increment for the dihydroxy substitution of pyridine is equal to the sum of the respective enthalpic increment of the monosubstituted pyridines

Thermochemistry of minerals stable near the earth's surface

International Nuclear Information System (INIS)

1990-01-01

The present proposal continues the evolution, of changing emphasis from silicate melts to glass and toward crystalline minerals stable in the shallow crustal environment, particularly amphiholes, micas, and related hydrous phases adding zeolites and carbonates to our areas of interest. This is made possible both by recent advances in our high-temperature calorimetric techniques and by an interest in extending our ideas about the systematics of ionic substitutions to more complex structures. The proposal presents the following: (a) a listing of papers, theses, and abstracts in the past 3 years supported by the present grant, (b) a summary of work on glasses containing highly charged cations and on some related crystalline phases, with proposed new directions, (c) a discussion of advances in calorimetric methods and what new possibilities they open, (d) completed and planned work on amphiboles, micas, and clays, (e) completed and proposed work on amorpous low temperature materials, (f) proposed work on zeolites, and (g) proposed work on carbonates and (h) a discussion of the energy relevance of the above projects. This is followed by the required forms, budget pages, and CV. 34 refs., 5 figs., 1 tab

Thermochemistry of brazing ceramics and metals in air

Energy Technology Data Exchange (ETDEWEB)

Bobzin, Kirsten; Schlaefer, Thomas; Kopp, Nils [RWTH Aachen (DE). Surface Engineering Inst. (IOT)

2011-08-15

Reactive air brazing offers economically and technologically advantageous joining of ceramics to metals. Solid oxide fuel cells and membranes for oxyfuel combustion are recent fields of application. However, it remains a problem that strong metallurgical reactions between brazes and base materials occur. These reactions were analysed by differential scanning calorimetry tests to get a better understanding. Therefore, three braze alloys (Ag8Cu, Ag8Cu0.5Ti and Ag4Cu4Ni) and five base materials (alumina, 3YSZ partially stabilised zirconia, BSCF perovskite ceramic, X1CrTi-La22 and X15CrNiSi25-20) were investigated. The reaction peaks correlate with the formation of reaction layers, which were observed in metallographic analysis of brazed specimens. The results help to explain the reaction mechanisms and allow optimised selection of filler metals and brazing temperature. (orig.)

Hypersonic Transition and Turbulence with Non-Equilibrium Thermochemistry

Science.gov (United States)

2009-08-31

from the literamre. In summary, this AFOSR MURI project has resulted in the production of new knowledge that should significantly improve the accuracy...behavior. The accumulated knowledge and understanding are expected to help development of better dissipation models for compressible flow fields. 2.23.2...8ffipüC<Pressurt Modieung suggestions from physics study <T acautttc Hypersonic Mach numbers Supersonic Mach numbers * skier * *a Subsonic

Thermochemistry and Reactivity of Metals Engaged in Chemiionization

Science.gov (United States)

2015-12-03

polarizable and polar molecules. 4 Accurate determination of metal-ligand BDEs using this approach requires that several factors be taken into account...chemistry outlined below, as well as recent work on the actinide thorium. 16 In this source, argon (about 10% in He) is ionized by a kV dc potential

Interacting boson model with surface delta interaction between nucleons: Structure and interaction of bosons

International Nuclear Information System (INIS)

Druce, C.H.; Moszkowski, S.A.

1986-01-01

The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. We have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson-proton-boson interaction for the case of degenerate orbits. A connection is made between these coefficients and the parameters of the interaction boson model Hamiltonian. A link between the latter parameters and the single boson energies is suggested

Interacting boson model with surface delta interaction between nucleons: Structure and interaction of bosons

Energy Technology Data Exchange (ETDEWEB)

Druce, C.H.; Moszkowski, S.A.

1986-01-01

The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. We have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson-proton-boson interaction for the case of degenerate orbits. A connection is made between these coefficients and the parameters of the interaction boson model Hamiltonian. A link between the latter parameters and the single boson energies is suggested.

Enthalpies of formation of dihydroxybenzenes revisited: Combining experimental and high-level ab initio data

International Nuclear Information System (INIS)

Gonçalves, Elsa M.; Agapito, Filipe; Almeida, Tânia S.; Martinho Simões, José A.

2014-01-01

Highlights: • Thermochemistry of hydroxyphenols probed by experimental and theoretical methods. • A new paradigm for obtaining enthalpies of formation of crystalline compounds. • High-level ab initio results for the thermochemistry of gas-phase hydroxyphenols. • Sublimation enthalpies of hydroxyphenols determined by Calvet microcalorimetry. - Abstract: Accurate values of standard molar enthalpies of formation in condensed phases can be obtained by combining high-level quantum chemistry calculations of gas-phase enthalpies of formation with experimentally determined enthalpies of sublimation or vapourization. The procedure is illustrated for catechol, resorcinol, and hydroquinone. Using W1-F12, the gas-phase enthalpies of formation of these compounds at T = 298.15 K were computed as (−270.6, −269.4, and −261.0) kJ · mol −1 , respectively, with an uncertainty of ∼0.4 kJ · mol −1 . Using well characterised solid samples, the enthalpies of sublimation were determined with a Calvet microcalorimeter, leading to the following values at T = 298.15 K: (88.3 ± 0.3) kJ · mol −1 , (99.7 ± 0.4) kJ · mol −1 , and (102.0 ± 0.9) kJ · mol −1 , respectively. It is shown that these results are consistent with the crystalline structures of the compounds

Towards nuclear energy applications other than electricity production

International Nuclear Information System (INIS)

Lecomte, M.

2007-01-01

Use of nuclear energy relies on operation of a boiler, involving practically no greenhouse gas emission. Whereas production of electricity is, nowadays, virtually its sole purpose, demand for heat production could equally arise, particularly with the emergence of high-temperature, or even very-high-temperature reactors. With the abilities this involves, as regards the recovery of heavy crude oils from tar sands, seawater desalination, or, most importantly, production of hydrogen by electrolysis, or thermochemistry, this being the energy carrier of tomorrow. (authors)

Computational quantum chemistry website

International Nuclear Information System (INIS)

1997-01-01

This report contains the contents of a web page related to research on the development of quantum chemistry methods for computational thermochemistry and the application of quantum chemistry methods to problems in material chemistry and chemical sciences. Research programs highlighted include: Gaussian-2 theory; Density functional theory; Molecular sieve materials; Diamond thin-film growth from buckyball precursors; Electronic structure calculations on lithium polymer electrolytes; Long-distance electronic coupling in donor/acceptor molecules; and Computational studies of NOx reactions in radioactive waste storage

Nonequilibrium effects on shock-layer radiometry during earth entry.

Science.gov (United States)

Arnold, J. O.; Whiting, E. E.

1973-01-01

Radiative enhancement factors for the CN violet and N2(+) first negative band systems caused by nonequilibrium thermochemistry in the shock layer of a blunt-nosed vehicle during earth entry are reported. The results are based on radiometric measurements obtained with the aid of a combustion-driven shock tube. The technique of converting the shock-tube measurements into predictions of the enhancement factors for the blunt-body case is described, showing it to be useful for similar applications of other shock-tube measurements.

Calculating the knowledge-based similarity of functional groups using crystallographic data

Science.gov (United States)

Watson, Paul; Willett, Peter; Gillet, Valerie J.; Verdonk, Marcel L.

2001-09-01

A knowledge-based method for calculating the similarity of functional groups is described and validated. The method is based on experimental information derived from small molecule crystal structures. These data are used in the form of scatterplots that show the likelihood of a non-bonded interaction being formed between functional group A (the `central group') and functional group B (the `contact group' or `probe'). The scatterplots are converted into three-dimensional maps that show the propensity of the probe at different positions around the central group. Here we describe how to calculate the similarity of a pair of central groups based on these maps. The similarity method is validated using bioisosteric functional group pairs identified in the Bioster database and Relibase. The Bioster database is a critical compilation of thousands of bioisosteric molecule pairs, including drugs, enzyme inhibitors and agrochemicals. Relibase is an object-oriented database containing structural data about protein-ligand interactions. The distributions of the similarities of the bioisosteric functional group pairs are compared with similarities for all the possible pairs in IsoStar, and are found to be significantly different. Enrichment factors are also calculated showing the similarity method is statistically significantly better than random in predicting bioisosteric functional group pairs.

Interacting boson model with surface delta interaction between nucleons

International Nuclear Information System (INIS)

Druce, C.; Moszkowski, S.A.

1984-01-01

The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. The authors have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson proton-boson interaction for the case of degenerate orbits

Measuring excess free energies of self-assembled membrane structures.

Science.gov (United States)

Norizoe, Yuki; Daoulas, Kostas Ch; Müller, Marcus

2010-01-01

Using computer simulation of a solvent-free, coarse-grained model for amphiphilic membranes, we study the excess free energy of hourglass-shaped connections (i.e., stalks) between two apposed bilayer membranes. In order to calculate the free energy by simulation in the canonical ensemble, we reversibly transfer two apposed bilayers into a configuration with a stalk in three steps. First, we gradually replace the intermolecular interactions by an external, ordering field. The latter is chosen such that the structure of the non-interacting system in this field closely resembles the structure of the original, interacting system in the absence of the external field. The absence of structural changes along this path suggests that it is reversible; a fact which is confirmed by expanded-ensemble simulations. Second, the external, ordering field is changed as to transform the non-interacting system from the apposed bilayer structure to two-bilayers connected by a stalk. The final external field is chosen such that the structure of the non-interacting system resembles the structure of the stalk in the interacting system without a field. On the third branch of the transformation path, we reversibly replace the external, ordering field by non-bonded interactions. Using expanded-ensemble techniques, the free energy change along this reversible path can be obtained with an accuracy of 10(-3)k(B)T per molecule in the n VT-ensemble. Calculating the chemical potential, we obtain the free energy of a stalk in the grandcanonical ensemble, and employing semi-grandcanonical techniques, we calculate the change of the excess free energy upon altering the molecular architecture. This computational strategy can be applied to compute the free energy of self-assembled phases in lipid and copolymer systems, and the excess free energy of defects or interfaces.

Instrumental interaction

OpenAIRE

Luciani , Annie

2007-01-01

International audience; The expression instrumental interaction as been introduced by Claude Cadoz to identify a human-object interaction during which a human manipulates a physical object - an instrument - in order to perform a manual task. Classical examples of instrumental interaction are all the professional manual tasks: playing violin, cutting fabrics by hand, moulding a paste, etc.... Instrumental interaction differs from other types of interaction (called symbolic or iconic interactio...

Specificity of molecular interactions in transient protein-protein interaction interfaces.

Science.gov (United States)

Cho, Kyu-il; Lee, KiYoung; Lee, Kwang H; Kim, Dongsup; Lee, Doheon

2006-11-15

In this study, we investigate what types of interactions are specific to their biological function, and what types of interactions are persistent regardless of their functional category in transient protein-protein heterocomplexes. This is the first approach to analyze protein-protein interfaces systematically at the molecular interaction level in the context of protein functions. We perform systematic analysis at the molecular interaction level using classification and feature subset selection technique prevalent in the field of pattern recognition. To represent the physicochemical properties of protein-protein interfaces, we design 18 molecular interaction types using canonical and noncanonical interactions. Then, we construct input vector using the frequency of each interaction type in protein-protein interface. We analyze the 131 interfaces of transient protein-protein heterocomplexes in PDB: 33 protease-inhibitors, 52 antibody-antigens, 46 signaling proteins including 4 cyclin dependent kinase and 26 G-protein. Using kNN classification and feature subset selection technique, we show that there are specific interaction types based on their functional category, and such interaction types are conserved through the common binding mechanism, rather than through the sequence or structure conservation. The extracted interaction types are C(alpha)-- H...O==C interaction, cation...anion interaction, amine...amine interaction, and amine...cation interaction. With these four interaction types, we achieve the classification success rate up to 83.2% with leave-one-out cross-validation at k = 15. Of these four interaction types, C(alpha)--H...O==C shows binding specificity for protease-inhibitor complexes, while cation-anion interaction is predominant in signaling complexes. The amine ... amine and amine...cation interaction give a minor contribution to the classification accuracy. When combined with these two interactions, they increase the accuracy by 3.8%. In the case of

Modeling nitrogen chemistry in combustion

DEFF Research Database (Denmark)

Glarborg, Peter; Miller, James A.; Ruscic, Branko

2018-01-01

the accuracy of engineering calculations and thereby the potential of primary measures for NOx control. In this review our current understanding of the mechanisms that are responsible for combustion-generated nitrogen-containing air pollutants is discussed. The thermochemistry of the relevant nitrogen...... via NNH or N2O are discussed, along with the chemistry of NO removal processes such as reburning and Selective Non-Catalytic Reduction of NO. Each subset of the mechanism is evaluated against experimental data and the accuracy of modeling predictions is discussed....

Chemistry WebBook

Science.gov (United States)

SRD 69 NIST Chemistry WebBook (Web, free access)   The NIST Chemistry WebBook contains: Thermochemical data for over 7000 organic and small inorganic compounds; thermochemistry data for over 8000 reactions; IR spectra for over 16,000 compounds; mass spectra for over 33,000 compounds; UV/Vis spectra for over 1600 compounds; electronic and vibrational spectra for over 5000 compounds; constants of diatomic molecules(spectroscopic data) for over 600 compounds; ion energetics data for over 16,000 compounds; thermophysical property data for 74 fluids.

A tabletop interactive storytelling system: designing for social interaction

NARCIS (Netherlands)

Alofs, Thijs; Theune, Mariet; Swartjes, I.M.T.

This paper presents the Interactive Storyteller, a multi-user interface for AI-based interactive storytelling, where stories emerge from the interaction of human players with intelligent characters in a simulated story world. To support face-to-face contact and social interaction, we position users

Trajectory dynamics study of the Ar + CH4 dissociation reaction at high temperatures: the importance of zero-point-energy effects.

Science.gov (United States)

Marques, J M C; Martínez-Núñez, E; Fernandez-Ramos, A; Vazquez, S A

2005-06-23

Large-scale classical trajectory calculations have been performed to study the reaction Ar + CH4--> CH3 +H + Ar in the temperature range 2500 energy surface used for ArCH4 is the sum of the nonbonding pairwise potentials of Hase and collaborators (J. Chem. Phys. 2001, 114, 535) that models the intermolecular interaction and the CH4 intramolecular potential of Duchovic et al. (J. Phys. Chem. 1984, 88, 1339), which has been modified to account for the H-H repulsion at small bending angles. The thermal rate coefficient has been calculated, and the zero-point energy (ZPE) of the CH3 product molecule has been taken into account in the analysis of the results; also, two approaches have been applied for discarding predissociative trajectories. In both cases, good agreement is observed between the experimental and trajectory results after imposing the ZPE of CH3. The energy-transfer parameters have also been obtained from trajectory calculations and compared with available values estimated from experiment using the master equation formalism; in general, the agreement is good.

Selective fluorescence quenching of nitrogen-containing polycyclic aromatic hydrocarbons by aliphatic amines

International Nuclear Information System (INIS)

Li Xiaoping; McGuffin, Victoria L.

2004-01-01

In this investigation, primary, secondary, and tertiary amines are evaluated for their efficiency and selectivity as fluorescence quenchers for polycyclic aromatic hydrocarbons (PAHs) and nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs). In general, the quenching efficiency tends to increase from primary to tertiary amine due to a greater number of alkyl groups that increase the electron-donating ability. However, the selectivity decreases from primary to tertiary amine. The effect of low concentrations of water is also examined. Because water can form hydrogen bonds with amines, the nonbonding electron pair is not available for interaction with the fluorophore, thus the quenching constant is decreased. These aliphatic amines are then applied to PAHs and N-PAHs and some interesting trends are observed. Whereas amino-PAHs remain virtually unquenched by different amines, aza-PAHs are all quenched well. The selectivity between aza-PAHs and amino-PAHs is as high as several hundred. This trend provides an easy and effective method to discriminate between these classes of N-PAHs. Moreover, the alternant aza-PAHs are quenched more than their corresponding alternant PAHs

Solid-Liquid Interface Thermal Resistance Affects the Evaporation Rate of Droplets from a Surface: A Study of Perfluorohexane on Chromium Using Molecular Dynamics and Continuum Theory.

Science.gov (United States)

Han, Haoxue; Schlawitschek, Christiane; Katyal, Naman; Stephan, Peter; Gambaryan-Roisman, Tatiana; Leroy, Frédéric; Müller-Plathe, Florian

2017-05-30

We study the role of solid-liquid interface thermal resistance (Kapitza resistance) on the evaporation rate of droplets on a heated surface by using a multiscale combination of molecular dynamics (MD) simulations and analytical continuum theory. We parametrize the nonbonded interaction potential between perfluorohexane (C 6 F 14 ) and a face-centered-cubic solid surface to reproduce the experimental wetting behavior of C 6 F 14 on black chromium through the solid-liquid work of adhesion (quantity directly related to the wetting angle). The thermal conductances between C 6 F 14 and (100) and (111) solid substrates are evaluated by a nonequilibrium molecular dynamics approach for a liquid pressure lower than 2 MPa. Finally, we examine the influence of the Kapitza resistance on evaporation of droplets in the vicinity of a three-phase contact line with continuum theory, where the thermal resistance of liquid layer is comparable with the Kapitza resistance. We determine the thermodynamic conditions under which the Kapitza resistance plays an important role in correctly predicting the evaporation heat flux.

A terahertz study of taurine: Dispersion correction and mode couplings

Science.gov (United States)

Dai, Zelin; Xu, Xiangdong; Gu, Yu; Li, Xinrong; Wang, Fu; Lian, Yuxiang; Fan, Kai; Cheng, Xiaomeng; Chen, Zhegeng; Sun, Minghui; Jiang, Yadong; Yang, Chun; Xu, Jimmy

2017-03-01

The low-frequency characteristics of polycrystalline taurine were studied experimentally by terahertz (THz) absorption spectroscopy and theoretically by ab initio density-functional simulations. Full optimizations with semi-empirical dispersion correction were performed in spectral computations and vibrational mode assignments. For comparison, partial optimizations with pure density functional theory were conducted in parallel. Results indicate that adding long-range dispersion correction to the standard DFT better reproduces the measured THz spectra than the popular partial optimizations. The main origins of the observed absorption features were also identified. Moreover, a coupled-oscillators model was proposed to explain the experimental observation of the unusual spectral blue-shift with the increase of temperature. Such coupled-oscillators model not only provides insights into the temperature dynamics of non-bonded interactions but also offers an opportunity to better understand the physical mechanisms behind the unusual THz spectral behaviors in taurine. Particularly, the simulation approach and novel coupled-oscillators model presented in this work are applicable to analyze the THz spectra of other molecular systems.

Weak interactions

International Nuclear Information System (INIS)

Ogava, S.; Savada, S.; Nakagava, M.

1983-01-01

The problem of the use of weak interaction laws to study models of elementary particles is discussed. The most typical examples of weak interaction is beta-decay of nucleons and muons. Beta-interaction is presented by quark currents in the form of universal interaction of the V-A type. Universality of weak interactions is well confirmed using as examples e- and μ-channels of pion decay. Hypothesis on partial preservation of axial current is applicable to the analysis of processes with pion participation. In the framework of the model with four flavours lepton decays of hadrons are considered. Weak interaction without lepton participation are also considered. Properties of neutral currents are described briefly

From Human-Computer Interaction to Human-Robot Social Interaction

OpenAIRE

Toumi, Tarek; Zidani, Abdelmadjid

2014-01-01

Human-Robot Social Interaction became one of active research fields in which researchers from different areas propose solutions and directives leading robots to improve their interactions with humans. In this paper we propose to introduce works in both human robot interaction and human computer interaction and to make a bridge between them, i.e. to integrate emotions and capabilities concepts of the robot in human computer model to become adequate for human robot interaction and discuss chall...

Effective interactions

International Nuclear Information System (INIS)

Elliott, J.P.

1981-01-01

This chapter attempts to describe and compare some of the more important nucleon-nucleon interactions that have been used in nuclear structure calculations, and to relate them where possible to the real nucleon-nucleon interaction. Explains that different interactions have been used depending on whether one is fitting to total binding energies and densities with a Hartree Fock (HF) calculation or fitting to spectra and spectroscopic data in a shell model calculation. Examines both types of calculation after two preliminary sections concerned with notation and with the philosophy underlying the use of model spaces and effective interactions. Discusses Skyrme interactions, finite range interactions, small model space, large model space, and the Sussex potential matrix elements. Focuses on the more empirical approaches in which a simple form is chosen for the effective interaction in a given model space and the parameters are deduced from fitting many-body data

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.

Evaluation of two processes of hydrogen production starting from energy generated by high temperature nuclear reactors; Evaluacion de dos procesos de produccion de hidrogeno a partir de energia generada por reactores nucleares de alta temperatura

Energy Technology Data Exchange (ETDEWEB)

Valle H, J., E-mail: jvalle@upmh.edu.mx [Universidad Politecnica Metropolitana de Hidalgo, Boulevard Acceso a Tolcayuca 1009, Ex-Hacienda San Javier, 43860 Tolcayuca, Hidalgo (Mexico)

2013-10-15

In this work an evaluation to two processes of hydrogen production using energy generated starting from high temperature nuclear reactors (HTGR's) was realized. The evaluated processes are the electrolysis of high temperature and the thermo-chemistry cycle Iodine-Sulfur. The electrolysis of high temperature, contrary to the conventional electrolysis, allows reaching efficiencies of up to 60% because when increasing the temperature of the water, giving thermal energy, diminishes the electric power demand required to separate the molecule of the water. However, to obtain these efficiencies is necessary to have water vapor overheated to more than 850 grades C, temperatures that can be reached by the HTGR. On the other hand the thermo-chemistry cycle Iodine-Sulfur, developed by General Atomics in the 1970 decade, requires two thermal levels basically, the great of them to 850 grades C for decomposition of H{sub 2}SO{sub 4} and another minor to 360 grades C approximately for decomposition of H I, a high temperature nuclear reactor can give the thermal energy required for the process whose products would be only hydrogen and oxygen. In this work these two processes are described, complete models are developed and analyzed thermodynamically that allow to couple each hydrogen generation process to a reactor HTGR that will be implemented later on for their dynamic simulation. The obtained results are presented in form of comparative data table of each process, and with them the obtained net efficiencies. (author)

Gaussian interaction profile kernels for predicting drug-target interaction.

Science.gov (United States)

van Laarhoven, Twan; Nabuurs, Sander B; Marchiori, Elena

2011-11-01

The in silico prediction of potential interactions between drugs and target proteins is of core importance for the identification of new drugs or novel targets for existing drugs. However, only a tiny portion of all drug-target pairs in current datasets are experimentally validated interactions. This motivates the need for developing computational methods that predict true interaction pairs with high accuracy. We show that a simple machine learning method that uses the drug-target network as the only source of information is capable of predicting true interaction pairs with high accuracy. Specifically, we introduce interaction profiles of drugs (and of targets) in a network, which are binary vectors specifying the presence or absence of interaction with every target (drug) in that network. We define a kernel on these profiles, called the Gaussian Interaction Profile (GIP) kernel, and use a simple classifier, (kernel) Regularized Least Squares (RLS), for prediction drug-target interactions. We test comparatively the effectiveness of RLS with the GIP kernel on four drug-target interaction networks used in previous studies. The proposed algorithm achieves area under the precision-recall curve (AUPR) up to 92.7, significantly improving over results of state-of-the-art methods. Moreover, we show that using also kernels based on chemical and genomic information further increases accuracy, with a neat improvement on small datasets. These results substantiate the relevance of the network topology (in the form of interaction profiles) as source of information for predicting drug-target interactions. Software and Supplementary Material are available at http://cs.ru.nl/~tvanlaarhoven/drugtarget2011/. tvanlaarhoven@cs.ru.nl; elenam@cs.ru.nl. Supplementary data are available at Bioinformatics online.

The IVTANTHERMO-Online database for thermodynamic properties of individual substances with web interface

Science.gov (United States)

Belov, G. V.; Dyachkov, S. A.; Levashov, P. R.; Lomonosov, I. V.; Minakov, D. V.; Morozov, I. V.; Sineva, M. A.; Smirnov, V. N.

2018-01-01

The database structure, main features and user interface of an IVTANTHERMO-Online system are reviewed. This system continues the series of the IVTANTHERMO packages developed in JIHT RAS. It includes the database for thermodynamic properties of individual substances and related software for analysis of experimental results, data fitting, calculation and estimation of thermodynamical functions and thermochemistry quantities. In contrast to the previous IVTANTHERMO versions it has a new extensible database design, the client-server architecture, a user-friendly web interface with a number of new features for online and offline data processing.

Ultrasound-promoted synthesis of (4 or 5-aryl-2-aryloyl-(1H-imidazoles in water

Directory of Open Access Journals (Sweden)

Behzad Khalili

2014-01-01

Full Text Available A green and efficient method for the synthesis of (4 or 5-aryl-2-aryloyl-(1H-imidazoles via self-condensation reaction of arylglyoxal hydrates in the presence of ammonium acetate using water as solvent under ultrasonic irradiation was reported. The reactions proceeded in high yields and very short reaction time. Introduced procedure is completely ecofriendly and don’t need any toxic organic solvent in all performing steps. In addition we use computational chemistry for acquiring some information about the thermochemistry and geometrical structure of these imidazole derivatives.

Growth, characterization and properties of CVD diamond films for applications as radiation detectors

International Nuclear Information System (INIS)

Sciorti, S.

1999-01-01

The aim of the work is to give a picture of the current state of the art of CVD (chemical vapour deposition) diamond. The interest is due to the capability to grow over large areas a material with physical properties suitable for an impressive number of applications. The authors focuses on the potential of diamond as a radiation detector and gets into details of the huge field that extends from the thermochemistry of the deposition process to the test of a diamond-based tracker with a fast readout electronics

Interacting dark sector with transversal interaction

Energy Technology Data Exchange (ETDEWEB)

Chimento, Luis P.; Richarte, Martín G. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, Pabellón I, Buenos Aires 1428 (Argentina)

2015-03-26

We investigate the interacting dark sector composed of dark matter, dark energy, and dark radiation for a spatially flat Friedmann-Robertson-Walker (FRW) background by introducing a three-dimensional internal space spanned by the interaction vector Q and solve the source equation for a linear transversal interaction. Then, we explore a realistic model with dark matter coupled to a scalar field plus a decoupled radiation term, analyze the amount of dark energy in the radiation era and find that our model is consistent with the recent measurements of cosmic microwave background anisotropy coming from Planck along with the future constraints achievable by CMBPol experiment.

Interaction for visualization

CERN Document Server

Tominski, Christian

2015-01-01

Visualization has become a valuable means for data exploration and analysis. Interactive visualization combines expressive graphical representations and effective user interaction. Although interaction is an important component of visualization approaches, much of the visualization literature tends to pay more attention to the graphical representation than to interaction.The goal of this work is to strengthen the interaction side of visualization. Based on a brief review of general aspects of interaction, we develop an interaction-oriented view on visualization. This view comprises five key as

Experimental and computational study on the thermochemistry of ethylpiperidines

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.; Gomes, Jose R.B.

2006-01-01

The standard (p o =0.1MPa) massic energies of combustion in oxygen of 1-ethylpiperidine and 2-ethylpiperidine, both in the liquid phase, were measured at T=298.15K by static bomb calorimetry. These values were used to derive the standard molar enthalpies of combustion and the standard molar enthalpies of formation, in the condensed phase, for these compounds. Further, the standard molar enthalpies of vaporization, at T=298.15K, of these two ethylpiperidine isomers were determined by Calvet microcalorimetry. The combustion calorimetry results together with those from the Calvet microcalorimetry, were used to derive the standard molar enthalpies of formation, at T=298.15K, in the gaseous phase.-Δ c H m o (l)/(kJ.mol -1 )Δ l g H m o /(kJ.mol -1 )1-Ethylpiperidine4776.8+/- 1.639.44+/-0.652-Ethylpiperidine4740.3+/-1.548.22+/-0.89 In parallel, theoretical calculations have been carried out for all the ethylpiperidine isomers, enabling the estimation of gas-phase enthalpies of formation for these compounds. The comparison with the present experimental data is very good and, thus, supports the quality of the results calculated for the 3-ethyl and 4-ethylpiperidines.

Prediction of Transition States and Thermochemistry for Combustion Reactions.

Science.gov (United States)

1984-04-07

ARO have yet received their degrees, although Mr. Sohrab Zarrabian and Mr. David Magers have been working on ARO projects. Postdoctoral students who...part of a review by Musher (20), and 2iiek & Paldus (21). The latter paper, as well as a review of much of the effort of our group (22), appears in...Schaefer (141), using SD-CI techniques and David - son’s correction to estimate the effects of quadruple excitations, deter- mined the barriers and

Thermochemistry of aqueous pyridine-3-carboxylic acid (nicotinic acid)

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Elsa M. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto Politecnico de Setubal, ESTBarreiro, Rua Americo da Silva Marinho, 2839-001 Lavradio (Portugal); Rego, Talita S. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Minas da Piedade, Manuel E., E-mail: memp@fc.ul.p [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal)

2011-06-15

Research highlights: {yields} We determined the {Delta}{sub sol}H{sub m} of solid nicotinic acid (NA) in water by solution calorimetry. {yields} We determined {Delta}{sub dil}H{sub m} of an aqueous nicotinic acid solution by flow calorimetry. {yields} We determined (aq, {infinity}) for the 3 NA species involved in acid/base equilibria. {yields} We determined the enthalpy of formation of NA(aq) under saturation conditions.. - Abstract: The molar enthalpy of solution of solid nicotinic acid (NA) at T = 298.15 K, to give an aqueous solution of molality m = 3.748 . 10{sup -3} mol {center_dot} kg{sup -1}, was determined as {Delta}{sub sol}H{sub m} = (19,927 {+-} 48) J {center_dot} mol{sup -1}, by solution calorimetry. Enthalpies of dilution, {Delta}{sub dil}H{sub m}, of 0.1005 mol {center_dot} kg{sup -1} aqueous nicotinic acid to yield final solutions with molality in the approximate range (0.03 to 0.09) mol {center_dot} kg{sup -1} were also measured by flow calorimetry. Combining the two sets of data and the results of pH measurements, with values of proton dissociation enthalpies and {Delta}{sub f}H{sub m}{sup 0}(NA, cr) selected from the literature, it was possible to derive the standard molar enthalpies of formation of the three nicotinic acid species involved in protonation/deprotonation equilibria, at infinite dilution: {Delta}{sub f}H{sub m}{sup 0}(HN{sup +}C{sub 5}H{sub 4}COOH.{infinity}H{sub 2}O,aq) = (328.2 {+-} 1.2) kJ {center_dot} mol{sup -1}, {Delta}{sub f}H{sub m}{sup 0}(HN{sup +}C{sub 5}H{sub 4}COO{sup -}.{infinity}H{sub 2}O,aq) = (325.0 {+-} 1.2) kJ {center_dot} mol{sup -1}, and {Delta}{sub f}H{sub m}{sup 0}(NC{sub 5}H{sub 4}COO{sup -}.{infinity}H{sub 2}O,aq) = (313.7 {+-} 1.2) kJ {center_dot} mol{sup -1}. Finally, the enthalpy of solution of nicotinic acid at T = 298.15 K, under saturation conditions (m = 0.138 mol {center_dot} kg{sup -1}), and the standard molar enthalpy of formation of the corresponding solution could also be obtained as {Delta}{sub sol}H{sub m}= (19,773 {+-} 48) J {center_dot} mol{sup -1} and {Delta}{sub f}H{sub m}{sup 0}(NA {center_dot} 402H{sub 2}O, aq) = (324.9 {+-} 1.2) kJ {center_dot} mol{sup -1}, respectively.

Thermochemistry of certain rare earth and ammonium double chlorides

International Nuclear Information System (INIS)

Usubaliev, D.U.; Abramtsev, V.A.; Kydynov, M.K.; Vilyaev, A.N.

1987-01-01

In a calorimeter with isothermal casing at 25 deg C dissolution enthalpies of double chlorides of rare earths and ammonium LnCl 3 x2NH 4 Cl (Ln=La, Sm) and LnCl 3 x3NH 4 Cl (Ln=Gd, Tb, Ho) in water, as well as dissolution enthalpy of rare earth chlorides in solution of ammonium chloride and NH 4 Cl in solution of rare earth chloride, have been measured. Formation enthalpies, standard formation enthalpies, dissociation enthalpies of the above-mentioned double chlorides are calculated

Thermochemistry of aqueous solutions of cerium and neodymium chlorides

International Nuclear Information System (INIS)

Monaenkova, A.S.; Umyarova, R.S.; Reshetnikova, L.P.; Vorob'ev, A.F.

1981-01-01

Enthalpies of CeCl 3 and NdCl 3 dissolving in water are measured at 298.15 K and at 0.03M and 0.01M concentration in the pressurized swing calorimeter with isothermal shell. Values of dissolving enthalpies for the samples of the salts, prepared by different methods coincide in the limits of measurement error

Intermolecular interactions

International Nuclear Information System (INIS)

Kaplan, I.G.; Rodimova, O.B.; AN SSSR, Tomsk. Inst. Optiki Atmosfery)

1978-01-01

The present state of the intermolecular interaction theory is described. The general physical picture of the molecular interactions is given, the relative contributions of interactions of different types are analyzed (electrostatic, resonance, induction, dispersion, relativistic, magnetostatic and exchange), and the main ones in each range of separations are picked out. The methods of the potential curve calculations are considered, specific for definite separations between the interacting systems. The special attention is paid to the analysis of approximations used in different theoretical calculation methods

Hazard interactions and interaction networks (cascades) within multi-hazard methodologies

Science.gov (United States)

Gill, Joel C.; Malamud, Bruce D.

2016-08-01

This paper combines research and commentary to reinforce the importance of integrating hazard interactions and interaction networks (cascades) into multi-hazard methodologies. We present a synthesis of the differences between multi-layer single-hazard approaches and multi-hazard approaches that integrate such interactions. This synthesis suggests that ignoring interactions between important environmental and anthropogenic processes could distort management priorities, increase vulnerability to other spatially relevant hazards or underestimate disaster risk. In this paper we proceed to present an enhanced multi-hazard framework through the following steps: (i) description and definition of three groups (natural hazards, anthropogenic processes and technological hazards/disasters) as relevant components of a multi-hazard environment, (ii) outlining of three types of interaction relationship (triggering, increased probability, and catalysis/impedance), and (iii) assessment of the importance of networks of interactions (cascades) through case study examples (based on the literature, field observations and semi-structured interviews). We further propose two visualisation frameworks to represent these networks of interactions: hazard interaction matrices and hazard/process flow diagrams. Our approach reinforces the importance of integrating interactions between different aspects of the Earth system, together with human activity, into enhanced multi-hazard methodologies. Multi-hazard approaches support the holistic assessment of hazard potential and consequently disaster risk. We conclude by describing three ways by which understanding networks of interactions contributes to the theoretical and practical understanding of hazards, disaster risk reduction and Earth system management. Understanding interactions and interaction networks helps us to better (i) model the observed reality of disaster events, (ii) constrain potential changes in physical and social vulnerability

Kinesthetic Interaction

DEFF Research Database (Denmark)

Fogtmann, Maiken Hillerup; Fritsch, Jonas; Kortbek, Karen Johanne

2008-01-01

Within the Human-Computer Interaction community there is a growing interest in designing for the whole body in interaction design. The attempts aimed at addressing the body have very different outcomes spanning from theoretical arguments for understanding the body in the design process, to more...... practical examples of designing for bodily potential. This paper presents Kinesthetic Interaction as a unifying concept for describing the body in motion as a foundation for designing interactive systems. Based on the theoretical foundation for Kinesthetic Interaction, a conceptual framework is introduced...... to reveal bodily potential in relation to three design themes – kinesthetic development, kinesthetic means and kinesthetic disorder; and seven design parameters – engagement, sociality, movability, explicit motivation, implicit motivation, expressive meaning and kinesthetic empathy. The framework is a tool...

Characterization of the Bonds Developed between Calcium Silicate Hydrate and Polycarboxylate-Based Superplasticizers with Silyl Functionalities

KAUST Repository

Orozco, Carlos A.

2017-03-24

Major developments in concrete technology have been achieved with the use of polycarboxylate-based superplasticizers (PCEs) to improve the concrete rheology without increasing the mix water content. Currently, it is possible to control the fluidity of the fresh concrete and obtain stronger and more durable structures. Therefore, there is a strong incentive to understand the interactions between PCEs and cement hydrates at the atomic scale to design new customized functional PCEs according to the ever-increasing requirements of the concrete industry. Here, the bonding types generated between a PCE with silyl functionalities (PCE-Sil) and a synthetic calcium silicate hydrate (C-S-H) are analyzed using XRD, 29Si NMR spectroscopy, and synchrotron-based techniques, such as NEXAFS and EXAFS. The results indicated that the carboxylic groups present in PCE-Sil interact by a ligand-type bond with calcium, which modified not only the symmetry and coordination number of the calcium located at the surface of C-S-H but also the neighboring silicon atoms of the C-S-H. In addition, the silyl functionalities of the PCE-Sil generated covalent bonds through siloxane bridges between the silanol groups of PCE-Sil and the nonbonding oxygen located at the dimeric sites in C-S-H, forming new bridging silicon sites and subsequently increasing the silicate polymerization.

Characterization of the Bonds Developed between Calcium Silicate Hydrate and Polycarboxylate-Based Superplasticizers with Silyl Functionalities.

Science.gov (United States)

Orozco, Carlos A; Chun, Byong W; Geng, Guoqing; Emwas, Abdul H; Monteiro, Paulo J M

2017-04-11

Major developments in concrete technology have been achieved with the use of polycarboxylate-based superplasticizers (PCEs) to improve the concrete rheology without increasing the mix water content. Currently, it is possible to control the fluidity of the fresh concrete and obtain stronger and more durable structures. Therefore, there is a strong incentive to understand the interactions between PCEs and cement hydrates at the atomic scale to design new customized functional PCEs according to the ever-increasing requirements of the concrete industry. Here, the bonding types generated between a PCE with silyl functionalities (PCE-Sil) and a synthetic calcium silicate hydrate (C-S-H) are analyzed using XRD, 29 Si NMR spectroscopy, and synchrotron-based techniques, such as NEXAFS and EXAFS. The results indicated that the carboxylic groups present in PCE-Sil interact by a ligand-type bond with calcium, which modified not only the symmetry and coordination number of the calcium located at the surface of C-S-H but also the neighboring silicon atoms of the C-S-H. In addition, the silyl functionalities of the PCE-Sil generated covalent bonds through siloxane bridges between the silanol groups of PCE-Sil and the nonbonding oxygen located at the dimeric sites in C-S-H, forming new bridging silicon sites and subsequently increasing the silicate polymerization.

Characterization of the Bonds Developed between Calcium Silicate Hydrate and Polycarboxylate-Based Superplasticizers with Silyl Functionalities

KAUST Repository

Orozco, Carlos A.; Chun, Byong W.; Geng, Guoqing; Emwas, Abdul-Hamid M.; Monteiro, Paulo J. M.

2017-01-01

Major developments in concrete technology have been achieved with the use of polycarboxylate-based superplasticizers (PCEs) to improve the concrete rheology without increasing the mix water content. Currently, it is possible to control the fluidity of the fresh concrete and obtain stronger and more durable structures. Therefore, there is a strong incentive to understand the interactions between PCEs and cement hydrates at the atomic scale to design new customized functional PCEs according to the ever-increasing requirements of the concrete industry. Here, the bonding types generated between a PCE with silyl functionalities (PCE-Sil) and a synthetic calcium silicate hydrate (C-S-H) are analyzed using XRD, 29Si NMR spectroscopy, and synchrotron-based techniques, such as NEXAFS and EXAFS. The results indicated that the carboxylic groups present in PCE-Sil interact by a ligand-type bond with calcium, which modified not only the symmetry and coordination number of the calcium located at the surface of C-S-H but also the neighboring silicon atoms of the C-S-H. In addition, the silyl functionalities of the PCE-Sil generated covalent bonds through siloxane bridges between the silanol groups of PCE-Sil and the nonbonding oxygen located at the dimeric sites in C-S-H, forming new bridging silicon sites and subsequently increasing the silicate polymerization.

Discovery of novel inhibitors of Mycobacterium tuberculosis MurG: homology modelling, structure based pharmacophore, molecular docking, and molecular dynamics simulations.

Science.gov (United States)

Saxena, Shalini; Abdullah, Maaged; Sriram, Dharmarajan; Guruprasad, Lalitha

2017-10-17

MurG (Rv2153c) is a key player in the biosynthesis of the peptidoglycan layer in Mycobacterium tuberculosis (Mtb). This work is an attempt to highlight the structural and functional relationship of Mtb MurG, the three-dimensional (3D) structure of protein was constructed by homology modelling using Discovery Studio 3.5 software. The quality and consistency of generated model was assessed by PROCHECK, ProSA and ERRAT. Later, the model was optimized by molecular dynamics (MD) simulations and the optimized model complex with substrate Uridine-diphosphate-N-acetylglucosamine (UD1) facilitated us to employ structure-based virtual screening approach to obtain new hits from Asinex database using energy-optimized pharmacophore modelling (e-pharmacophore). The pharmacophore model was validated using enrichment calculations, and finally, validated model was employed for high-throughput virtual screening and molecular docking to identify novel Mtb MurG inhibitors. This study led to the identification of 10 potential compounds with good fitness, docking score, which make important interactions with the protein active site. The 25 ns MD simulations of three potential lead compounds with protein confirmed that the structure was stable and make several non-bonding interactions with amino acids, such as Leu290, Met310 and Asn167. Hence, we concluded that the identified compounds may act as new leads for the design of Mtb MurG inhibitors.

An in situ FTIR step-scan photoacoustic investigation of kerogen and minerals in oil shale.

Science.gov (United States)

Alstadt, Kristin N; Katti, Dinesh R; Katti, Kalpana S

2012-04-01

Step-scan photoacoustic infrared spectroscopy experiments were performed on Green River oil shale samples obtained from the Piceance Basin located in Colorado, USA. We have investigated the molecular nature of light and dark colored areas of the oil shale core using FTIR photoacoustic step-scan spectroscopy. This technique provided us with the means to analyze the oil shale in its original in situ form with the kerogen-mineral interactions intact. All vibrational bands characteristic of kerogen were found in the dark and light colored oil shale samples confirming that kerogen is present throughout the depth of the core. Depth profiling experiments indicated that there are changes between layers in the oil shale molecular structure at a length scale of micron. Comparisons of spectra from the light and dark colored oil shale core samples suggest that the light colored regions have high kerogen content, with spectra similar to that from isolated kerogen, whereas, the dark colored areas contain more mineral components which include clay minerals, dolomite, calcite, and pyrite. The mineral components of the oil shale are important in understanding how the kerogen is "trapped" in the oil shale. Comparing in situ kerogen spectra with spectra from isolated kerogen indicate significant band shifts suggesting important nonbonded molecular interactions between the kerogen and minerals. Copyright © 2011 Elsevier B.V. All rights reserved.

Playful Interaction

DEFF Research Database (Denmark)

2003-01-01

The video Playful Interaction describes a future architectural office, and envisions ideas and concepts for playful interactions between people, materials and appliances in a pervasive and augmented working environment. The video both describes existing developments, technologies and designs...... as well as ideas not yet implemented such as playful modes of interaction with an augmented ball. Playful Interaction has been used as a hybrid of a vision video and a video prototype (1). Externally the video has been used to visualising our new ideas, and internally the video has also worked to inspire...

Molecular Dynamics Simulation of Nanoindentation-induced Mechanical Deformation and Phase Transformation in Monocrystalline Silicon

Directory of Open Access Journals (Sweden)

Jian Sheng-Rui

2008-01-01

Full Text Available AbstractThis work presents the molecular dynamics approach toward mechanical deformation and phase transformation mechanisms of monocrystalline Si(100 subjected to nanoindentation. We demonstrate phase distributions during loading and unloading stages of both spherical and Berkovich nanoindentations. By searching the presence of the fifth neighboring atom within a non-bonding length, Si-III and Si-XII have been successfully distinguished from Si-I. Crystallinity of this mixed-phase was further identified by radial distribution functions.

Firm Investment and Balance-Sheet Problems in Japan

OpenAIRE

Toshitaka Sekine

1999-01-01

This paper investigates whether balance-sheet conditions of firms and their main banks matter for firm investment behavior using dynamic corporate panel data in Japan for the period 1985-95. It finds that smaller non-bond issuing firms were facing liquidity constraints; these firms’ balance-sheet conditions (the debt asset ratios) affected their investment from the midst of the bubble era by influencing main banks’ lending to them; and the deterioration of their main banks’ balance-sheet cond...

Educational interactive multimedia software: The impact of interactivity on learning

Science.gov (United States)

Reamon, Derek Trent

This dissertation discusses the design, development, deployment and testing of two versions of educational interactive multimedia software. Both versions of the software are focused on teaching mechanical engineering undergraduates about the fundamentals of direct-current (DC) motor physics and selection. The two versions of Motor Workshop software cover the same basic materials on motors, but differ in the level of interactivity between the students and the software. Here, the level of interactivity refers to the particular role of the computer in the interaction between the user and the software. In one version, the students navigate through information that is organized by topic, reading text, and viewing embedded video clips; this is referred to as "low-level interactivity" software because the computer simply presents the content. In the other version, the students are given a task to accomplish---they must design a small motor-driven 'virtual' vehicle that competes against computer-generated opponents. The interaction is guided by the software which offers advice from 'experts' and provides contextual information; we refer to this as "high-level interactivity" software because the computer is actively participating in the interaction. The software was used in two sets of experiments, where students using the low-level interactivity software served as the 'control group,' and students using the highly interactive software were the 'treatment group.' Data, including pre- and post-performance tests, questionnaire responses, learning style characterizations, activity tracking logs and videotapes were collected for analysis. Statistical and observational research methods were applied to the various data to test the hypothesis that the level of interactivity effects the learning situation, with higher levels of interactivity being more effective for learning. The results show that both the low-level and high-level interactive versions of the software were effective

Effective interactions in p-shell nuclei and the realistic interactions - I

International Nuclear Information System (INIS)

Upadhyaya, G.K.; Joshi, K.P.

1984-04-01

The effective interaction of Jain et al. derived from the Yale interaction by including the prominent core polarization diagrams is analyzed in terms of the interaction radial integrals and their spin tensor components. The interaction is also compared with some phenomenological effective interactions. The general features of the effective force in the 1 p shell region are discussed. (author)

Evaluation of drug interaction microcomputer software: Dambro's Drug Interactions.

Science.gov (United States)

Poirier, T I; Giudici, R A

1990-01-01

Dambro's Drug Interactions was evaluated using general and specific criteria. The installation process, ease of learning and use were rated excellent. The user documentation and quality of the technical support were good. The scope of coverage, clinical documentation, frequency of updates, and overall clinical performance were fair. The primary advantages of the program are the quick searching and detection of drug interactions, and the attempt to provide useful interaction data, i.e., significance and reference. The disadvantages are the lack of current drug interaction information, outdated references, lack of evaluative drug interaction information, and the inability to save or print patient profiles. The program is not a good value for the pharmacist but has limited use as a quick screening tool.

Food-Drug Interactions

Directory of Open Access Journals (Sweden)

Arshad Yar Khan

2011-03-01

Full Text Available The effect of drug on a person may be different than expected because that drug interacts with another drug the person is taking (drug-drug interaction, food, beverages, dietary supplements the person is consuming (drug-nutrient/food interaction or another disease the person has (drug-disease interaction. A drug interaction is a situation in which a substance affects the activity of a drug, i.e. the effects are increased or decreased, or they produce a new effect that neither produces on its own. These interactions may occur out of accidental misuse or due to lack of knowledge about the active ingredients involved in the relevant substances. Regarding food-drug interactions physicians and pharmacists recognize that some foods and drugs, when taken simultaneously, can alter the body's ability to utilize a particular food or drug, or cause serious side effects. Clinically significant drug interactions, which pose potential harm to the patient, may result from changes in pharmaceutical, pharmacokinetic, or pharmacodynamic properties. Some may be taken advantage of, to the benefit of patients, but more commonly drug interactions result in adverse drug events. Therefore it is advisable for patients to follow the physician and doctors instructions to obtain maximum benefits with least fooddrug interactions. The literature survey was conducted by extracting data from different review and original articles on general or specific drug interactions with food. This review gives information about various interactions between different foods and drugs and will help physicians and pharmacists prescribe drugs cautiously with only suitable food supplement to get maximum benefit for the patient.

Molecular dynamics simulations and thermochemistry of reactive ion etching of silicon by chlorine, chlorine dimer, bromine, and bromine dimer cations

Energy Technology Data Exchange (ETDEWEB)

Valone, S.M.; Hanson, D.E.; Kress, J.D.

1998-05-08

Simulations of Cl plasma etch of Si surfaces with MD techniques agree reasonably well with the available experimental information on yields and surface morphologies. This information has been supplied to a Monte Carlo etch profile resulting in substantial agreement with comparable inputs provided through controlled experiments. To the extent that more recent measurements of etch rates are more reliable than older ones, preliminary MD simulations using bond-order corrections to the atomic interactions between neighboring Si atoms on the surface improves agreement with experiment through an increase in etch rate and improved agreement with XPS measurements of surface stoichiometry. Thermochemical and geometric analysis of small Si-Br molecules is consistent with the current notions of the effects of including brominated species in etchant gases.

Ferrocene-based guanidine derivatives: in vitro antimicrobial, DNA binding and docking supported urease inhibition studies.

Science.gov (United States)

Gul, Rukhsana; Rauf, Muhammad Khawar; Badshah, Amin; Azam, Syed Sikander; Tahir, Muhammad Nawaz; Khan, Azim

2014-10-06

Some novel ferrocenyl guanidines 1-8 were synthesized and characterized by different spectroscopic methods, elemental analysis and single crystal X-rays diffraction techniques. The crystallographic studies revealed that the existence of the strong non-bonding interactions facilitate these molecules to interact with biological macro-molecules like DNA that described to inherit good biological activities. The DNA interaction studies carried out by cyclic voltammetry (CV) and UV-visible spectroscopy are in close agreement with the binding constants (K) (0.79-5.4) × 10(5) (CV) and (0.72-5.1) × 10(5) (UV-vis). The shift in peak potential, current and absorption maxima of the studied ferrocenyl guanidines in the presence of DNA revealed that CV coupled with UV-vis spectroscopy could provide an opportune to characterize metal-based compounds-DNA interaction mechanism, a prerequisite for the design of new anticancer agents and understanding the molecular basis of their action. The compounds 1-8 have been screened for their antibacterial, antifungal and urease inhibition potency. A concurrent in silico study has also been applied on ferrocene moiety impregnated guanidines 1-8 to identify most active compounds having for inhibiting the activity of urease (pdb id 3LA4). Most of the compounds were found as potent inhibitors of urease and the compound 1 was found to be the most active with an IC50 of 16.83 ± 0.03 μM. The docking scores are in close agreement with the in vitro obtained IC50 values of inhibitors 1-8. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Interacting With Robots to Investigate the Bases of Social Interaction.

Science.gov (United States)

Sciutti, Alessandra; Sandini, Giulio

2017-12-01

Humans show a great natural ability at interacting with each other. Such efficiency in joint actions depends on a synergy between planned collaboration and emergent coordination, a subconscious mechanism based on a tight link between action execution and perception. This link supports phenomena as mutual adaptation, synchronization, and anticipation, which cut drastically the delays in the interaction and the need of complex verbal instructions and result in the establishment of joint intentions, the backbone of social interaction. From a neurophysiological perspective, this is possible, because the same neural system supporting action execution is responsible of the understanding and the anticipation of the observed action of others. Defining which human motion features allow for such emergent coordination with another agent would be crucial to establish more natural and efficient interaction paradigms with artificial devices, ranging from assistive and rehabilitative technology to companion robots. However, investigating the behavioral and neural mechanisms supporting natural interaction poses substantial problems. In particular, the unconscious processes at the basis of emergent coordination (e.g., unintentional movements or gazing) are very difficult-if not impossible-to restrain or control in a quantitative way for a human agent. Moreover, during an interaction, participants influence each other continuously in a complex way, resulting in behaviors that go beyond experimental control. In this paper, we propose robotics technology as a potential solution to this methodological problem. Robots indeed can establish an interaction with a human partner, contingently reacting to his actions without losing the controllability of the experiment or the naturalness of the interactive scenario. A robot could represent an "interactive probe" to assess the sensory and motor mechanisms underlying human-human interaction. We discuss this proposal with examples from our

Interactive pinball business

DEFF Research Database (Denmark)

Buur, Jacob; Gudiksen, Sune Klok

2012-01-01

Interaction design expands into new fields. Interaction design and business model innovation is a promising meeting of disciplines: Many businesses see the need to rethink their ways of doing business, and, as business models pose highly dynamic and interactive problems, interaction design has much...... with hypotheses and experiment with scenarios as a way of innovating their business models, and why this is so...... to offer. This paper compares 'tangible business models' in the form of pinball-like contraptions, designed by interaction design students with those developed by groups of professionals around concrete business issues. We will show how the interactive models encourage business people to play...

Final State Interactions Effects in Neutrino-Nucleus Interactions

Energy Technology Data Exchange (ETDEWEB)

Golan, Tomasz [Univ. of Wroctaw (Poland); Juszczak, Cezary [Univ. of Wroctaw (Poland); Sobczyk, Jan T. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

2012-07-01

Final State Interactions effects are discussed in the context of Monte Carlo simulations of neutrino-nucleus interactions. A role of Formation Time is explained and several models describing this effect are compared. Various observables which are sensitive to FSI effects are reviewed including pion-nucleus interaction and hadron yields in backward hemisphere. NuWro Monte Carlo neutrino event generator is described and its ability to understand neutral current $\\pi^0$ production data in $\\sim 1$ GeV neutrino flux experiments is demonstrated.

Multiresolution Modeling of Semidilute Polymer Solutions: Coarse-Graining Using Wavelet-Accelerated Monte Carlo

Directory of Open Access Journals (Sweden)

Animesh Agarwal

2017-09-01

Full Text Available We present a hierarchical coarse-graining framework for modeling semidilute polymer solutions, based on the wavelet-accelerated Monte Carlo (WAMC method. This framework forms a hierarchy of resolutions to model polymers at length scales that cannot be reached via atomistic or even standard coarse-grained simulations. Previously, it was applied to simulations examining the structure of individual polymer chains in solution using up to four levels of coarse-graining (Ismail et al., J. Chem. Phys., 2005, 122, 234901 and Ismail et al., J. Chem. Phys., 2005, 122, 234902, recovering the correct scaling behavior in the coarse-grained representation. In the present work, we extend this method to the study of polymer solutions, deriving the bonded and non-bonded potentials between coarse-grained superatoms from the single chain statistics. A universal scaling function is obtained, which does not require recalculation of the potentials as the scale of the system is changed. To model semi-dilute polymer solutions, we assume the intermolecular potential between the coarse-grained beads to be equal to the non-bonded potential, which is a reasonable approximation in the case of semidilute systems. Thus, a minimal input of microscopic data is required for simulating the systems at the mesoscopic scale. We show that coarse-grained polymer solutions can reproduce results obtained from the more detailed atomistic system without a significant loss of accuracy.

Effect of metal doping on structural characteristics of amorphous carbon system: A first-principles study

Energy Technology Data Exchange (ETDEWEB)

Li, Xiaowei; Zhang, Dong [Key Laboratory of Marine Materials and Related Technologies, Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Lee, Kwang-Ryeol, E-mail: krlee@kist.re.kr [Computational Science Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Wang, Aiying, E-mail: aywang@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2016-05-31

First-principles calculation was performed to investigate the effect of metal doping on the structural characteristics of amorphous carbon system, and the 3d transition metals (TM) were particularly selected as representative case. Results showed that the total energy in TM–C systems caused by distorting the bond angles was reduced distinctly for comparison with that in C–C system. Further electronic structure revealed that as the 3d electrons of doped TM increased, the bond characteristic of highest occupied molecular orbital changed from bonding (Sc, Ti) to nonbonding (V, Cr, Mn, Fe) and finally to antibonding (Co, Ni, Cu) between the TM and C atoms. Meanwhile, the TM–C bond presented a mixture of the covalent and ionic characters. The decrease of strength and directionality of TM–C bonds resulted in the total energy change upon bond angle distortion, which demonstrated that the bond characteristics played an important role in reducing residual stress of TM-doped amorphous carbon systems. - Highlights: • The bond characteristics as 3d electrons changed from bonding, nonbonding to antibonding. • The TM–C bond was a mixture of covalent and ionic characters. • Reduced strength and directionality of TM–C bond led to small distortion energy change. • The weak TM–C bond accounted for the reduced compressive stress caused by TM.

Exploration of molecular interactions in cholesterol superlattices: effect of multibody interactions.

Science.gov (United States)

Huang, Juyang

2002-08-01

Experimental evidences have indicated that cholesterol may adapt highly regular lateral distributions (i.e., superlattices) in a phospholipid bilayer. We investigated the formations of superlattices at cholesterol mole fraction of 0.154, 0.25, 0.40, and 0.5 using Monte Carlo simulation. We found that in general, conventional pairwise-additive interactions cannot produce superlattices. Instead, a multibody (nonpairwise) interaction is required. Cholesterol superlattice formation reveals that although the overall interaction between cholesterol and phospholipids is favorable, it contains two large opposing components: an interaction favoring cholesterol-phospholipid mixing and an unfavorable acyl chain multibody interaction that increases nonlinearly with the number of cholesterol contacts. The magnitudes of interactions are in the order of kT. The physical origins of these interactions can be explained by our umbrella model. They most likely come from the requirement for polar phospholipid headgroups to cover the nonpolar cholesterol to avoid the exposure of cholesterol to water and from the sharp decreasing of acyl chain conformation entropy due to cholesterol contact. This study together with our previous work demonstrate that the driving force of cholesterol-phospholipid mixing is a hydrophobic interaction, and multibody interactions dominate others over a wide range of cholesterol concentration.

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

KAUST Repository

Bugler, John

2015-07-16

© 2015 American Chemical Society. This paper describes our developing understanding of low-temperature oxidation kinetics. We have investigated the ignition of the three pentane isomers in a rapid compression machine over a wide range of temperatures and pressures, including conditions of negative temperature coefficient behavior. The pentane isomers are small alkanes, yet have structures that are complex enough to allow for the application of their kinetic and thermochemical rules to larger molecules. Updates to the thermochemistry of the species important in the low-temperature oxidation of hydrocarbons have been made based on a thorough literature review. An evaluation of recent quantum-chemically derived rate coefficients from the literature pertinent to important low-temperature oxidation reaction classes has been performed, and new rate rules are recommended for these classes. Several reaction classes have also been included to determine their importance with regard to simulation results, and we have found that they should be included when developing future chemical kinetic mechanisms. A comparison of the model simulations with pressure-time histories from experiments in a rapid compression machine shows very good agreement for both ignition delay time and pressure rise for both the first- and second-stage ignition events. We show that revisions to both the thermochemistry and the kinetics are required in order to replicate experiments well. A broader validation of the models with ignition delay times from shock tubes and a rapid compression machine is presented in an accompanying paper. The results of this study enhance our understanding of the combustion of straight- and branched-chained alkanes.

Redox regulation of protein tyrosine phosphatase 1B (PTP1B): Importance of steric and electronic effects on the unusual cyclization of the sulfenic acid intermediate to a sulfenyl amide

Science.gov (United States)

Sarma, Bani Kanta

2013-09-01

The redox regulation of protein tyrosine phosphatase 1B (PTP1B) via the unusual transformation of its sulfenic acid (PTP1B-SOH) to a cyclic sulfenyl amide intermediate is studied by using small molecule chemical models. These studies suggest that the sulfenic acids derived from the H2O2-mediated reactions o-amido thiophenols do not efficiently cyclize to sulfenyl amides and the sulfenic acids produced in situ can be trapped by using methyl iodide. Theoretical calculations suggest that the most stable conformer of such sulfenic acids are stabilized by nO → σ*S-OH orbital interactions, which force the -OH group to adopt a position trans to the S⋯O interaction, leading to an almost linear arrangement of the O⋯S-O moiety and this may be the reason for the slow cyclization of such sulfenic acids to their corresponding sulfenyl amides. On the other hand, additional substituents at the 6-position of o-amido phenylsulfenic acids that can induce steric environment and alter the electronic properties around the sulfenic acid moiety by S⋯N or S⋯O nonbonded interactions destabilize the sulfenic acids by inducing strain in the molecule. This may lead to efficient the cyclization of such sulfenic acids. This model study suggests that the amino acid residues in the close proximity of the sulfenic acid moiety in PTP1B may play an important role in the cyclization of PTP1B-SOH to produce the corresponding sulfenyl amide.

Floor interaction

DEFF Research Database (Denmark)

Petersen, Marianne Graves; Krogh, Peter; Ludvigsen, Martin

2005-01-01

Within architecture, there is a long tradition of careful design of floors. The design has been concerned with both decorating floors and designing floors to carry information. Ubiquitous computing technology offers new opportunities for designing interactive floors. This paper presents three...... different interactive floor concepts. Through an urban perspective it draws upon the experiences of floors in architecture, and provides a set of design issues for designing interactive floors....

Interaction debugging : an integral approach to analyze human-robot interaction

NARCIS (Netherlands)

Kooijmans, T.; Kanda, T.; Bartneck, C.; Ishiguro, H.; Hagita, N.

2006-01-01

Along with the development of interactive robots, controlled experiments and field trials are regularly conducted to stage human-robot interaction. Experience in this field has shown that analyzing human-robot interaction for evaluation purposes fosters the development of improved systems and the

Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments

DEFF Research Database (Denmark)

Kjaer, Christina; Stockett, Mark H.; Pedersen, Bjarke Møller

2016-01-01

The microenvironments in photosynthetic proteins affect the absorption by chlorophyll (Chl) pigments. It is, however, a challenge to disentangle the impact on the transition energies of different perturbations, for example, the global electrostatics of the protein (nonbonded environmental effects......), exciton coupling between Chl's, conformational variations, and binding of an axial ligand to the magnesium center. This is needed to distinguish between the two most commonly proposed mechanisms for energy transport in photosynthetic proteins, relying on either weakly or strongly coupled pigments. Here...

Visualization of Host-Polerovirus Interaction Topologies Using Protein Interaction Reporter Technology.

Science.gov (United States)

DeBlasio, Stacy L; Chavez, Juan D; Alexander, Mariko M; Ramsey, John; Eng, Jimmy K; Mahoney, Jaclyn; Gray, Stewart M; Bruce, James E; Cilia, Michelle

2016-02-15

Demonstrating direct interactions between host and virus proteins during infection is a major goal and challenge for the field of virology. Most protein interactions are not binary or easily amenable to structural determination. Using infectious preparations of a polerovirus (Potato leafroll virus [PLRV]) and protein interaction reporter (PIR), a revolutionary technology that couples a mass spectrometric-cleavable chemical cross-linker with high-resolution mass spectrometry, we provide the first report of a host-pathogen protein interaction network that includes data-derived, topological features for every cross-linked site that was identified. We show that PLRV virions have hot spots of protein interaction and multifunctional surface topologies, revealing how these plant viruses maximize their use of binding interfaces. Modeling data, guided by cross-linking constraints, suggest asymmetric packing of the major capsid protein in the virion, which supports previous epitope mapping studies. Protein interaction topologies are conserved with other species in the Luteoviridae and with unrelated viruses in the Herpesviridae and Adenoviridae. Functional analysis of three PLRV-interacting host proteins in planta using a reverse-genetics approach revealed a complex, molecular tug-of-war between host and virus. Structural mimicry and diversifying selection-hallmarks of host-pathogen interactions-were identified within host and viral binding interfaces predicted by our models. These results illuminate the functional diversity of the PLRV-host protein interaction network and demonstrate the usefulness of PIR technology for precision mapping of functional host-pathogen protein interaction topologies. The exterior shape of a plant virus and its interacting host and insect vector proteins determine whether a virus will be transmitted by an insect or infect a specific host. Gaining this information is difficult and requires years of experimentation. We used protein interaction

Study of thermal stability and degradation of fire resistant candidate polymers for aircraft interiors

Science.gov (United States)

Hsu, M. T. S.

1976-01-01

The thermochemistry of bismaleimide resins and phenolphthalein polycarbonate was studied. Both materials are fire-resistant polymers and may be suitable for aircraft interiors. The chemical composition of the polymers has been determined by nuclear magnetic resonance and infrared spectroscopy and by elemental analysis. Thermal properties of these polymers have been characterized by thermogravimetric analyses. Qualitative evaluation of the volatile products formed in pyrolysis under oxidative and non-oxidative conditions has been made using infrared spectrometry. The residues after pyrolysis were analyzed by elemental analysis. The thermal stability of composite panel and thermoplastic materials for aircraft interiors was studied by thermogravimetric analyses.

Bibliography on transuranium elements

International Nuclear Information System (INIS)

Sood, D.D.

1991-01-01

A selective bibliography of prominent publications on transuranium elements is compiled. Heading papers, symposia proceedings and the textbooks are included in the bibliography. The bibliography is arranged under the headings: (1)Books, Symposia Proceedings, Reviews etc., (2)Discovery, (3)Weighable Isolation, (4)Metal Preparation, (5)Nuclear Properties, (6)Plutonium as Reactor Fuel, (7)Fuel Reprocessing, (8)Solid State Chemistry, Thermochemistry and Spectroscopy, (9)Radiation Safety, (10)Applications, and (11)Some Typical Indian Papers. Total number of references cited are 298. The bibliography, though selective, will serve as a starting point for comprehensive literature search on transuranium elements. (author)

Surprising performance for vibrational frequencies of the distinguishable clusters with singles and doubles (DCSD) and MP2.5 approximations

Science.gov (United States)

Kesharwani, Manoj K.; Sylvetsky, Nitai; Martin, Jan M. L.

2017-11-01

We show that the DCSD (distinguishable clusters with all singles and doubles) correlation method permits the calculation of vibrational spectra at near-CCSD(T) quality but at no more than CCSD cost, and with comparatively inexpensive analytical gradients. For systems dominated by a single reference configuration, even MP2.5 is a viable alternative, at MP3 cost. MP2.5 performance for vibrational frequencies is comparable to double hybrids such as DSD-PBEP86-D3BJ, but without resorting to empirical parameters. DCSD is also quite suitable for computing zero-point vibrational energies in computational thermochemistry.

Conformational energies of DNA sugar-phosphate backbone: Reference QM calculations and a comparison with density functional theory and molecular mechanics

Czech Academy of Sciences Publication Activity Database

Mládek, Arnošt; Šponer, Judit E.; Jurečka, P.; Banáš, P.; Otyepka, M.; Svozil, D.; Šponer, Jiří

2010-01-01

Roč. 6, č. 12 (2010), s. 3817-3835 ISSN 1549-9618 R&D Projects: GA AV ČR(CZ) IAA400040802; GA ČR(CZ) GA203/09/1476; GA ČR(CZ) GAP208/10/2302 Grant - others:GA ČR(CZ) GD203/09/H046; GA MŠk(CZ) LC06030; GA MŠk(CZ) LC512 Program:GD; LC; LC Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : intramolecular hydrogen-bonds * main-group thermochemistry * set superposition error Subject RIV: BO - Biophysics Impact factor: 5.138, year: 2010

CALPHAD calculation of phase diagrams : a comprehensive guide

CERN Document Server

Saunders, N; Miodownik, A P

1998-01-01

This monograph acts as a benchmark to current achievements in the field of Computer Coupling of Phase Diagrams and Thermochemistry, often called CALPHAD which is an acronym for Computer CALculation of PHAse Diagrams. It also acts as a guide to both the basic background of the subject area and the cutting edge of the topic, combining comprehensive discussions of the underlying physical principles of the CALPHAD method with detailed descriptions of their application to real complex multi-component materials. Approaches which combine both thermodynamic and kinetic models to interpret non-equilibrium phase transformations are also reviewed.

Interacting steps with finite-range interactions: Analytical approximation and numerical results

Science.gov (United States)

Jaramillo, Diego Felipe; Téllez, Gabriel; González, Diego Luis; Einstein, T. L.

2013-05-01

We calculate an analytical expression for the terrace-width distribution P(s) for an interacting step system with nearest- and next-nearest-neighbor interactions. Our model is derived by mapping the step system onto a statistically equivalent one-dimensional system of classical particles. The validity of the model is tested with several numerical simulations and experimental results. We explore the effect of the range of interactions q on the functional form of the terrace-width distribution and pair correlation functions. For physically plausible interactions, we find modest changes when next-nearest neighbor interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms.

Detecting mutually exclusive interactions in protein-protein interaction maps.

KAUST Repository

Sánchez Claros, Carmen

2012-06-08

Comprehensive protein interaction maps can complement genetic and biochemical experiments and allow the formulation of new hypotheses to be tested in the system of interest. The computational analysis of the maps may help to focus on interesting cases and thereby to appropriately prioritize the validation experiments. We show here that, by automatically comparing and analyzing structurally similar regions of proteins of known structure interacting with a common partner, it is possible to identify mutually exclusive interactions present in the maps with a sensitivity of 70% and a specificity higher than 85% and that, in about three fourth of the correctly identified complexes, we also correctly recognize at least one residue (five on average) belonging to the interaction interface. Given the present and continuously increasing number of proteins of known structure, the requirement of the knowledge of the structure of the interacting proteins does not substantially impact on the coverage of our strategy that can be estimated to be around 25%. We also introduce here the Estrella server that embodies this strategy, is designed for users interested in validating specific hypotheses about the functional role of a protein-protein interaction and it also allows access to pre-computed data for seven organisms.

Detecting mutually exclusive interactions in protein-protein interaction maps.

KAUST Repository

Sá nchez Claros, Carmen; Tramontano, Anna

2012-01-01

Comprehensive protein interaction maps can complement genetic and biochemical experiments and allow the formulation of new hypotheses to be tested in the system of interest. The computational analysis of the maps may help to focus on interesting cases and thereby to appropriately prioritize the validation experiments. We show here that, by automatically comparing and analyzing structurally similar regions of proteins of known structure interacting with a common partner, it is possible to identify mutually exclusive interactions present in the maps with a sensitivity of 70% and a specificity higher than 85% and that, in about three fourth of the correctly identified complexes, we also correctly recognize at least one residue (five on average) belonging to the interaction interface. Given the present and continuously increasing number of proteins of known structure, the requirement of the knowledge of the structure of the interacting proteins does not substantially impact on the coverage of our strategy that can be estimated to be around 25%. We also introduce here the Estrella server that embodies this strategy, is designed for users interested in validating specific hypotheses about the functional role of a protein-protein interaction and it also allows access to pre-computed data for seven organisms.

Drug Interaction API

Data.gov (United States)

U.S. Department of Health & Human Services — The Interaction API is a web service for accessing drug-drug interactions. No license is needed to use the Interaction API. Currently, the API uses DrugBank for its...

Rapid Computation of Thermodynamic Properties over Multidimensional Nonbonded Parameter Spaces Using Adaptive Multistate Reweighting.

Science.gov (United States)

Naden, Levi N; Shirts, Michael R

2016-04-12

We show how thermodynamic properties of molecular models can be computed over a large, multidimensional parameter space by combining multistate reweighting analysis with a linear basis function approach. This approach reduces the computational cost to estimate thermodynamic properties from molecular simulations for over 130,000 tested parameter combinations from over 1000 CPU years to tens of CPU days. This speed increase is achieved primarily by computing the potential energy as a linear combination of basis functions, computed from either modified simulation code or as the difference of energy between two reference states, which can be done without any simulation code modification. The thermodynamic properties are then estimated with the Multistate Bennett Acceptance Ratio (MBAR) as a function of multiple model parameters without the need to define a priori how the states are connected by a pathway. Instead, we adaptively sample a set of points in parameter space to create mutual configuration space overlap. The existence of regions of poor configuration space overlap are detected by analyzing the eigenvalues of the sampled states' overlap matrix. The configuration space overlap to sampled states is monitored alongside the mean and maximum uncertainty to determine convergence, as neither the uncertainty or the configuration space overlap alone is a sufficient metric of convergence. This adaptive sampling scheme is demonstrated by estimating with high precision the solvation free energies of charged particles of Lennard-Jones plus Coulomb functional form with charges between -2 and +2 and generally physical values of σij and ϵij in TIP3P water. We also compute entropy, enthalpy, and radial distribution functions of arbitrary unsampled parameter combinations using only the data from these sampled states and use the estimates of free energies over the entire space to examine the deviation of atomistic simulations from the Born approximation to the solvation free energy.

Weak interactions

International Nuclear Information System (INIS)

Chanda, R.

1981-01-01

The theoretical and experimental evidences to form a basis for Lagrangian Quantum field theory for Weak Interactions are discussed. In this context, gauge invariance aspects of such interactions are showed. (L.C.) [pt

Drug-radiopharmaceutical interactions

International Nuclear Information System (INIS)

Hladik, W.B.; Ponto, J.A.; Stathis, V.J.

1985-01-01

Patients seen in the nuclear medicine department have a wide variety of disorders and, consequently, may be receiving any number of therapeutic drugs. For this reason, nuclear medicine professionals should be aware of the potential effects that these pharmacologic agents may have on the bio-distribution of subsequently administered radiopharmaceuticals, commonly referred to as ''drug-radiopharmaceutical interactions.'' Compared with the quantity of literature written about interactions between various therapeutic drugs, the information available on drug-radiopharmaceutical interactions is scarce. However, there has been increasing interest in this subject, particularly during the past five years. Some of the reported interactions are used intentionally to add a new dimension to the nuclear medicine study and increase its diagnostic capabilities, i.e., pharmacologic intervention. These beneficial ''interactions'' are discussed in detail in several other chapters of this book. Other interactions, however, cause changes in the normal distribution of radiopharmaceuticals, which may interfere with the diagnostic utility of various nuclear medicine procedures. The latter group of interactions is the focus of this chapter

Food-drug interactions

DEFF Research Database (Denmark)

Schmidt, Lars E; Dalhoff, Kim

2002-01-01

Interactions between food and drugs may inadvertently reduce or increase the drug effect. The majority of clinically relevant food-drug interactions are caused by food-induced changes in the bioavailability of the drug. Since the bioavailability and clinical effect of most drugs are correlated......, the bioavailability is an important pharmacokinetic effect parameter. However, in order to evaluate the clinical relevance of a food-drug interaction, the impact of food intake on the clinical effect of the drug has to be quantified as well. As a result of quality review in healthcare systems, healthcare providers...... are increasingly required to develop methods for identifying and preventing adverse food-drug interactions. In this review of original literature, we have tried to provide both pharmacokinetic and clinical effect parameters of clinically relevant food-drug interactions. The most important interactions are those...

The cation-π interaction.

Science.gov (United States)

Dougherty, Dennis A

2013-04-16

The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author's perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forego aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction (Li(+) binds to benzene with 38 kcal/mol of binding energy; NH4(+) with 19 kcal/mol) distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2-5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) C(δ-)-H(δ+) bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li(+) > Na(+) > K(+) > Rb(+): as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane is

The 'Interactive' of Interactive Storytelling: Customizing the Gaming Experience

OpenAIRE

Bostan , Barbaros; Marsh , Tim

2010-01-01

International audience; In this article, we define interactive storytelling as a gaming experience where the form and content of the game is customized in real time and tailored to the preferences and needs of the player to maximixe enjoyment. The primary focus of interactive storytelling should not be on the attributes of the technology or characteristics of the medium, such as the AI techniques, planning formalisms, story representations, etc. but on different interaction levels provided by...

The effect of interactive digital storytelling gamification on microbiology classroom interactions

OpenAIRE

Molnar, Andreea

2018-01-01

In this research, we study the use of interactive digital storytelling in teaching microbiology. More specifically, we carried out an exploratory study assessing the effect of using the gamification of an interactive digital storytelling on classroom dynamics and students’ interaction. The results show that the presence of gamification led to an increase in classroom discussions and in students’ engagement with the learning objectives taught by the interactive digital storytelling.

The n→π* Interaction.

Science.gov (United States)

Newberry, Robert W; Raines, Ronald T

2017-08-15

The carbonyl group holds a prominent position in chemistry and biology not only because it allows diverse transformations but also because it supports key intermolecular interactions, including hydrogen bonding. More recently, carbonyl groups have been found to interact with a variety of nucleophiles, including other carbonyl groups, in what we have termed an n→π* interaction. In an n→π* interaction, a nucleophile donates lone-pair (n) electron density into the empty π* orbital of a nearby carbonyl group. Mixing of these orbitals releases energy, resulting in an attractive interaction. Hints of such interactions were evident in small-molecule crystal structures as early as the 1970s, but not until 2001 was the role of such interactions articulated clearly. These non-covalent interactions were first discovered during investigations into the thermostability of the proline-rich protein collagen, which achieves a robust structure despite a relatively low potential for hydrogen bonding. It was found that by modulating the distance between two carbonyl groups in the peptide backbone, one could alter the conformational preferences of a peptide bond to proline. Specifically, only the trans conformation of a peptide bond to proline allows for an attractive interaction with an adjacent carbonyl group, so when one increases the proximity of the two carbonyl groups, one enhances their interaction and promotes the trans conformation of the peptide bond, which increases the thermostability of collagen. More recently, attention has been paid to the nature of these interactions. Some have argued that rather than resulting from electron donation, carbonyl interactions are a particular example of dipolar interactions that are well-approximated by classical mechanics. However, experimental evidence has demonstrated otherwise. Numerous examples now exist where an increase in the dipole moment of a carbonyl group decreases the strength of its interactions with other carbonyl

Coarse-grained molecular dynamics simulations of polymerization with forward and backward reactions.

Science.gov (United States)

Krajniak, Jakub; Zhang, Zidan; Pandiyan, Sudharsan; Nies, Eric; Samaey, Giovanni

2018-06-11

We develop novel parallel algorithms that allow molecular dynamics simulations in which byproduct molecules are created and removed because of the chemical reactions during the molecular dynamics simulation. To prevent large increases in the potential energy, we introduce the byproduct molecules smoothly by changing the non-bonded interactions gradually. To simulate complete equilibrium reactions, we allow the byproduct molecules attack and destroy created bonds. Modeling of such reactions are, for instance, important to study the pore formation due to the presence of e.g. water molecules or development of polymer morphology during the process of splitting off byproduct molecules. Another concept that could be studied is the degradation of polymeric materials, a very important topic in a recycling of polymer waste. We illustrate the method by simulating the polymerization of polyethylene terephthalate (PET) at the coarse-grained level as an example of a polycondensation reaction with water as a byproduct. The algorithms are implemented in a publicly available software package and are easily accessible using a domain-specific language that describes chemical reactions in an input configuration file. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

A computer program for lattice-dynamical evaluation of Debye-Waller factors and thermodynamic functions for minerals, starting from empirical force fields

International Nuclear Information System (INIS)

Pilati, T.; Dermartin, F.; Gramaccioli, C.M.

1993-01-01

A wide-purpose computer program has been written (Fortran) for lattice dynamical evaluation of crystallographic and thermodynamic properties of solids, especially minerals or inorganic substances.The program essentially consists of a routine affording first and second derivatives of energy with respect to mass weighted coordinates, properly modulated by a wave vector algorithm, so that diagonalization can immediately follow and arrive at frequencies, density of states, and eventually to thermodynamic functions and Debye-Waller parameters thorough an automatic Brillouin-zone sampling procedure. The input consists of crystallographic data (unit-cell parameters, space group symmetry operations, atomic coordinates), plus atomic charge and empirical parameters, such as force constants or non-bonded atom-atom interaction energy functions in almost any form. It is also possible to obtain the structure corresponding to the energy minimum, or even to work with partial rigid bodies, in order to reduce the order of the dynamical matrices. The program provides for automatic symmetry labelling of the vibrational modes, in order to compare them with the experimental data; there is possibility of improving the empirical functions through a minimization routine. Examples of application and transferability of force fields to a series of minerals are provided. (author)

Determination of the protonation state of the Asp dyad: conventional molecular dynamics versus thermodynamic integration.

Science.gov (United States)

Huang, Jinfeng; Zhu, Yali; Sun, Bin; Yao, Yuan; Liu, Junjun

2016-03-01

The protonation state of the Asp dyad is important as it can reveal enzymatic mechanisms, and the information this provides can be used in the development of drugs for proteins such as memapsin 2 (BACE-1), HIV-1 protease, and rennin. Conventional molecular dynamics (MD) simulations have been successfully used to determine the preferred protonation state of the Asp dyad. In the present work, we demonstrate that the results obtained from conventional MD simulations can be greatly influenced by the particular force field applied or the values used for control parameters. In principle, free-energy changes between possible protonation states can be used to determine the protonation state. We show that protonation state prediction by the thermodynamic integration (TI) method is insensitive to force field version or to the cutoff for calculating nonbonded interactions (a control parameter). In the present study, the protonation state of the Asp dyad predicted by TI calculations was the same regardless of the force field and cutoff value applied. Contrary to the intuition that conventional MD is more efficient, our results clearly show that the TI method is actually more efficient and more reliable for determining the protonation state of the Asp dyad.

Inelastic neutron scattering, Raman, vibrational analysis with anharmonic corrections, and scaled quantum mechanical force field for polycrystalline L-alanine

Energy Technology Data Exchange (ETDEWEB)

Williams, Robert W. [Department of Biomedical Informatics, Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD 20815 (United States)], E-mail: bob@bob.usuhs.mil; Schluecker, Sebastian [Institute of Physical Chemistry, University of Wuerzburg, Wuerzburg (Germany); Hudson, Bruce S. [Department of Chemistry, Syracuse University, Syracuse, NY (United States)

2008-01-22

A scaled quantum mechanical harmonic force field (SQMFF) corrected for anharmonicity is obtained for the 23 K L-alanine crystal structure using van der Waals corrected periodic boundary condition density functional theory (DFT) calculations with the PBE functional. Scale factors are obtained with comparisons to inelastic neutron scattering (INS), Raman, and FT-IR spectra of polycrystalline L-alanine at 15-23 K. Calculated frequencies for all 153 normal modes differ from observed frequencies with a standard deviation of 6 wavenumbers. Non-bonded external k = 0 lattice modes are included, but assignments to these modes are presently ambiguous. The extension of SQMFF methodology to lattice modes is new, as are the procedures used here for providing corrections for anharmonicity and van der Waals interactions in DFT calculations on crystals. First principles Born-Oppenheimer molecular dynamics (BOMD) calculations are performed on the L-alanine crystal structure at a series of classical temperatures ranging from 23 K to 600 K. Corrections for zero-point energy (ZPE) are estimated by finding the classical temperature that reproduces the mean square displacements (MSDs) measured from the diffraction data at 23 K. External k = 0 lattice motions are weakly coupled to bonded internal modes.

Inelastic neutron scattering, Raman, vibrational analysis with anharmonic corrections, and scaled quantum mechanical force field for polycrystalline L-alanine

International Nuclear Information System (INIS)

Williams, Robert W.; Schluecker, Sebastian; Hudson, Bruce S.

2008-01-01

A scaled quantum mechanical harmonic force field (SQMFF) corrected for anharmonicity is obtained for the 23 K L-alanine crystal structure using van der Waals corrected periodic boundary condition density functional theory (DFT) calculations with the PBE functional. Scale factors are obtained with comparisons to inelastic neutron scattering (INS), Raman, and FT-IR spectra of polycrystalline L-alanine at 15-23 K. Calculated frequencies for all 153 normal modes differ from observed frequencies with a standard deviation of 6 wavenumbers. Non-bonded external k = 0 lattice modes are included, but assignments to these modes are presently ambiguous. The extension of SQMFF methodology to lattice modes is new, as are the procedures used here for providing corrections for anharmonicity and van der Waals interactions in DFT calculations on crystals. First principles Born-Oppenheimer molecular dynamics (BOMD) calculations are performed on the L-alanine crystal structure at a series of classical temperatures ranging from 23 K to 600 K. Corrections for zero-point energy (ZPE) are estimated by finding the classical temperature that reproduces the mean square displacements (MSDs) measured from the diffraction data at 23 K. External k = 0 lattice motions are weakly coupled to bonded internal modes

Structure of Insulin: Results of joint neutron and X-ray refinement

Energy Technology Data Exchange (ETDEWEB)

Wlodawer, A; Savage, H; Dodson, G

1989-02-01

Neutron diffraction data for porcine 2Zn insulin were collected to 2.2 A resolution from a single crystal deuterated by slow exchange of mother liquor. A joint neutron/X-ray restrained-least-squares refinement was undertaken using the neutron data, as well as the 1.5 A resolution X-ray data collected previously. The final R factors were 0.182 for the X-ray data and 0.191 for the neutron data. Resulting atomic coordinates were compared with the initial X-ray model, showing a total r.m.s. shift of 0.36 A for the protein and 0.6 A for the solvent. Protonation of a number of individual amino acids was investigated by analysis of the neutron maps. No D atoms were found between the carboxylates of Glu B13 which make an intermolecular contact, suggesting nonbonded interaction rather than the predicted hydrogen bond. Amide hydrogen exchange was investigated in a refinement of their atomic occupancies. Regions of unexchanged amide groups were found in the center of the B helices. The results of this study emphasize the limited amount of information available in neutron diffraction studies of proteins at resolution lower than 2 A.

Interaction graphs

DEFF Research Database (Denmark)

Seiller, Thomas

2016-01-01

Interaction graphs were introduced as a general, uniform, construction of dynamic models of linear logic, encompassing all Geometry of Interaction (GoI) constructions introduced so far. This series of work was inspired from Girard's hyperfinite GoI, and develops a quantitative approach that should...... be understood as a dynamic version of weighted relational models. Until now, the interaction graphs framework has been shown to deal with exponentials for the constrained system ELL (Elementary Linear Logic) while keeping its quantitative aspect. Adapting older constructions by Girard, one can clearly define...... "full" exponentials, but at the cost of these quantitative features. We show here that allowing interpretations of proofs to use continuous (yet finite in a measure-theoretic sense) sets of states, as opposed to earlier Interaction Graphs constructions were these sets of states were discrete (and finite...

Programming Interactivity

CERN Document Server

Noble, Joshua

2012-01-01

Ready to create rich interactive experiences with your artwork, designs, or prototypes? This is the ideal place to start. With this hands-on guide, you'll explore several themes in interactive art and design-including 3D graphics, sound, physical interaction, computer vision, and geolocation-and learn the basic programming and electronics concepts you need to implement them. No previous experience is necessary. You'll get a complete introduction to three free tools created specifically for artists and designers: the Processing programming language, the Arduino microcontroller, and the openFr

Guided ion beam and theoretical studies of the bond energy of SmS+

Science.gov (United States)

Armentrout, P. B.; Demireva, Maria; Peterson, Kirk A.

2017-12-01

Previous work has shown that atomic samarium cations react with carbonyl sulfide to form SmS+ + CO in an exothermic and barrierless process. To characterize this reaction further, the bond energy of SmS+ is determined in the present study using guided ion beam tandem mass spectrometry. Reactions of SmS+ with Xe, CO, and O2 are examined. Results for collision-induced dissociation processes with all three molecules along with the endothermicity of the SmS+ + CO → Sm+ + COS exchange reaction are combined to yield D0(Sm+-S) = 3.37 ± 0.20 eV. The CO and O2 reactions also yield a SmSO+ product, with measured endothermicities that indicate D0(SSm+-O) = 3.73 ± 0.16 eV and D0(OSm+-S) = 1.38 ± 0.27 eV. The SmS+ bond energy is compared with theoretical values characterized at several levels of theory, including CCSD(T) complete basis set extrapolations using all-electron basis sets. Multireference configuration interaction calculations with explicit spin-orbit calculations along with composite thermochemistry using the Feller-Peterson-Dixon method and all-electron basis sets were also explored for SmS+, and for comparison, SmO, SmO+, and EuO.

Explicit Interaction

DEFF Research Database (Denmark)

Löwgren, Jonas; Eriksen, Mette Agger; Linde, Per

2006-01-01

We report an ongoing study of palpable computing to support surgical rehabilitation, in the general field of interaction design for ubiquitous computing. Through explorative design, fieldwork and participatory design techniques, we explore the design principle of explicit interaction as an interp...

Philosophy of Interaction

DEFF Research Database (Denmark)

Svanæs, Dag

2011-01-01

This is an encyclopedia entry for the Interaction-Design.org free IxD encyclopedia. The topic of the entry is the application of the philosophy of Heidegger and Merleau-Ponty to a theory of interactivity. Comments by Don Norman and Eva Hornecker.......This is an encyclopedia entry for the Interaction-Design.org free IxD encyclopedia. The topic of the entry is the application of the philosophy of Heidegger and Merleau-Ponty to a theory of interactivity. Comments by Don Norman and Eva Hornecker....

Vision-based interaction

CERN Document Server

Turk, Matthew

2013-01-01

In its early years, the field of computer vision was largely motivated by researchers seeking computational models of biological vision and solutions to practical problems in manufacturing, defense, and medicine. For the past two decades or so, there has been an increasing interest in computer vision as an input modality in the context of human-computer interaction. Such vision-based interaction can endow interactive systems with visual capabilities similar to those important to human-human interaction, in order to perceive non-verbal cues and incorporate this information in applications such

A Mobile Personal Informatics System with Interactive Visualizations of Mobility and Social Interactions

DEFF Research Database (Denmark)

Cuttone, Andrea; Jørgensen, Sune Lehmann; Larsen, Jakob Eg

2013-01-01

We describe a personal informatics system for Android smartphones that provides personal data on mobility and social interactions through interactive visualization interfaces. The mobile app has been made available to N=136 first year university students as part of a study of social network...... interactions in a university campus setting. The design of the interactive visualization interfaces enabling the participants to gain insights into own behaviors is described. We report initial findings based on device logging of participant interactions with the interactive visualization app on the smartphone...

Study of the Deformation/Interaction Model: How Interactions Increase the Reaction Barrier

Directory of Open Access Journals (Sweden)

Zhiling Liang

2018-01-01

Full Text Available The interactions (including weak interactions between dienophiles and dienes play an important role in the Diels-Alder reaction. To elucidate the influence of these interactions on the reactivity, a popular DFT functional and a variational DFT functional corrected with dispersion terms are used to investigate different substituent groups incorporated on the dienophiles and dienes. The bond order is used to track the trajectory of the cycloaddition reaction. The deformation/interaction model is used to obtain the interaction energy from the reactant complex to the inflection point until reaching the saddle point. The interaction energy initially increases with a decrease in the interatomic distance, reaching a maximum value, but then decreases when the dienophiles and dienes come closer. Reduced density gradient and chemical energy component analysis are used to analyse the interaction. Traditional transition state theory and variational transition state theory are used to obtain the reaction rates. The influence of tunneling on the reaction rate is also discussed.

Aesthetic interaction

DEFF Research Database (Denmark)

Petersen, Marianne Graves; Iversen, Ole Sejer; Krogh, Peter

2004-01-01

, as it promotes aesthetics of use, rather than aesthetics of appearance. We coin this approach in the perspective of aesthetic interaction. Finally we make the point that aesthetics is not re-defining everything known about interactive systems. We provide a framework placing this perspective among other...

Inferring domain-domain interactions from protein-protein interactions with formal concept analysis.

Directory of Open Access Journals (Sweden)

Susan Khor

Full Text Available Identifying reliable domain-domain interactions will increase our ability to predict novel protein-protein interactions, to unravel interactions in protein complexes, and thus gain more information about the function and behavior of genes. One of the challenges of identifying reliable domain-domain interactions is domain promiscuity. Promiscuous domains are domains that can occur in many domain architectures and are therefore found in many proteins. This becomes a problem for a method where the score of a domain-pair is the ratio between observed and expected frequencies because the protein-protein interaction network is sparse. As such, many protein-pairs will be non-interacting and domain-pairs with promiscuous domains will be penalized. This domain promiscuity challenge to the problem of inferring reliable domain-domain interactions from protein-protein interactions has been recognized, and a number of work-arounds have been proposed. This paper reports on an application of Formal Concept Analysis to this problem. It is found that the relationship between formal concepts provides a natural way for rare domains to elevate the rank of promiscuous domain-pairs and enrich highly ranked domain-pairs with reliable domain-domain interactions. This piggybacking of promiscuous domain-pairs onto less promiscuous domain-pairs is possible only with concept lattices whose attribute-labels are not reduced and is enhanced by the presence of proteins that comprise both promiscuous and rare domains.

Inferring Domain-Domain Interactions from Protein-Protein Interactions with Formal Concept Analysis

Science.gov (United States)

Khor, Susan

2014-01-01

Identifying reliable domain-domain interactions will increase our ability to predict novel protein-protein interactions, to unravel interactions in protein complexes, and thus gain more information about the function and behavior of genes. One of the challenges of identifying reliable domain-domain interactions is domain promiscuity. Promiscuous domains are domains that can occur in many domain architectures and are therefore found in many proteins. This becomes a problem for a method where the score of a domain-pair is the ratio between observed and expected frequencies because the protein-protein interaction network is sparse. As such, many protein-pairs will be non-interacting and domain-pairs with promiscuous domains will be penalized. This domain promiscuity challenge to the problem of inferring reliable domain-domain interactions from protein-protein interactions has been recognized, and a number of work-arounds have been proposed. This paper reports on an application of Formal Concept Analysis to this problem. It is found that the relationship between formal concepts provides a natural way for rare domains to elevate the rank of promiscuous domain-pairs and enrich highly ranked domain-pairs with reliable domain-domain interactions. This piggybacking of promiscuous domain-pairs onto less promiscuous domain-pairs is possible only with concept lattices whose attribute-labels are not reduced and is enhanced by the presence of proteins that comprise both promiscuous and rare domains. PMID:24586450

Thermochemistry of uranium(VI), arsenic, and alkali metal triple oxides

International Nuclear Information System (INIS)

Karyakin, N.V.; Chernorukov, G.N.

1994-01-01

The standard enthalpies of reactions of stoichiometric mixtures of potassium dyhydrogen orthoarsenate, uranium(VI) oxide, alkali metal nitrates, and of mixtures of triple oxides with the general formula M I AsUO 6 (M I =Li, Na, K, Rb, and Cs) and potassium nitrate with aqueous solution of hydrofluoric acid were determined an an adiabatic calorimeter at 298.15 K. The standard enthalpies of formation of uranium(VI), arsenic, and alkali metal triple oxides at 298.15 K were calculated form the data obtained. 8 refs., 1 tab

CFD Analysis of Hypersonic Flowfields With Surface Thermochemistry and Ablation

Science.gov (United States)

Henline, W. D.

1997-01-01

In the past forty years much progress has been made in computational methods applied to the solution of problems in spacecraft hypervelocity flow and heat transfer. Although the basic thermochemical and physical modeling techniques have changed little in this time, several orders of magnitude increase in the speed of numerically solving the Navier-Stokes and associated energy equations have been achieved. The extent to which this computational power can be applied to the design of spacecraft heat shields is dependent on the proper coupling of the external flow equations to the boundary conditions and governing equations representing the thermal protection system in-depth conduction, pyrolysis and surface ablation phenomena. A discussion of the techniques used to do this in past problems as well as the current state-of-art is provided. Specific examples, including past missions such as Galileo, together with the more recent case studies of ESA/Rosetta Sample Comet Return, Mars Pathfinder and X-33 will be discussed. Modeling assumptions, design approach and computational methods and results are presented.

Advanced software for the calculation of thermochemistry, kinetics, and dynamics

International Nuclear Information System (INIS)

Shepard, R; Wagner, A F; Gray, S K

2006-01-01

The Born-Oppenheimer separation of the Schrodinger equation allows the electronic and nuclear motions to be solved in three steps. 1) The solution of the electronic wave function at a discrete set of molecular conformations; 2) the fitting of this discrete set of energy values in order to construct an analytical approximation to the potential energy surface (PES) at all molecular conformations; 3) the use of this analytical PES to solve for the nuclear motion using either time-dependent or time-independent formulations to compute molecular energy values, chemical reaction rates, and cumulative reaction probabilities. This project involves the development of technology to address all three of these steps. This report focuses on our recent work on the optimization of nonlinear wave function parameters for the electronic wave functions

Convergence in Multispecies Interactions.

Science.gov (United States)

Bittleston, Leonora S; Pierce, Naomi E; Ellison, Aaron M; Pringle, Anne

2016-04-01

The concepts of convergent evolution and community convergence highlight how selective pressures can shape unrelated organisms or communities in similar ways. We propose a related concept, convergent interactions, to describe the independent evolution of multispecies interactions with similar physiological or ecological functions. A focus on convergent interactions clarifies how natural selection repeatedly favors particular kinds of associations among species. Characterizing convergent interactions in a comparative context is likely to facilitate prediction of the ecological roles of organisms (including microbes) in multispecies interactions and selective pressures acting in poorly understood or newly discovered multispecies systems. We illustrate the concept of convergent interactions with examples: vertebrates and their gut bacteria; ectomycorrhizae; insect-fungal-bacterial interactions; pitcher-plant food webs; and ants and ant-plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Designing for Interactional Empowerment

OpenAIRE

Ståhl, Anna

2014-01-01

This thesis further defines how to reach Interactional Empowerment through design for users. Interactional Empowerment is an interaction design program within the general area of affective interaction, focusing on the users’ abil­ity to reflect, express themselves and engage in profound meaning-making. This has been explored through design of three systems eMoto, Affective Di­ary and Affective Health, which all mirror users’ emotions or bodily reactions in interaction in some way. From these ...

Interaction region

International Nuclear Information System (INIS)

Anon.

1982-01-01

The Interaction Region Group addressed the basic questions of how to collide the SLC beams, how to maximize and monitor the luminosity, and how to minimize the detector backgrounds at the interaction region. In practice, five subgroups evolved to study these questions. The final focus group provided three alternative designs to acheive the 1 to 2 micron beam spot size required by the SLC, as well as studying other problems including: eta, eta' matching from the collider arcs, the implementation of soft bends near the interaction region, beam emittance growth, and magnet tolerances in the final focus. The beam position monitor group proposed two devices, a strip line monitor, and a beamstrahlung monitor, to bring the beams into collision. The luminosity monitor group reviewed the possible QED processes that would be insensitive to weak interaction (Z 0 ) effects. The beam dumping group proposed locations for kicker and septum magnets in the final focus that would achieve a high dumping efficiency and would meet the desired beam tolerances at the Moller scattering target in the beam dump line. Working with the Polarization Group, the Moller experiment was designed into the beam dump beam line. A beam dump was proposed that would maintain radiation backgrounds (penetrating muons) at acceptible levels. The detector backgrounds group proposed soft-bend and masking configurations to shield the detector from synchrotron radiation from the hard/soft bends and from the final focus quadrupoles and evaluated the effectiveness of these designs for the three final focus optics designs. Backgrounds were also estimated from: large angle synchrotron radiation, local and distant beam-gas interactions, 2-photon interactions, and from neutrons and backscattered photons from the beamstrahlung dump

Elucidating the Interdependence of Drug Resistance from Combinations of Mutations.

Science.gov (United States)

Ragland, Debra A; Whitfield, Troy W; Lee, Sook-Kyung; Swanstrom, Ronald; Zeldovich, Konstantin B; Kurt-Yilmaz, Nese; Schiffer, Celia A

2017-11-14

HIV-1 protease is responsible for the cleavage of 12 nonhomologous sites within the Gag and Gag-Pro-Pol polyproteins in the viral genome. Under the selective pressure of protease inhibition, the virus evolves mutations within (primary) and outside of (secondary) the active site, allowing the protease to process substrates while simultaneously countering inhibition. The primary protease mutations impede inhibitor binding directly, while the secondary mutations are considered accessory mutations that compensate for a loss in fitness. However, the role of secondary mutations in conferring drug resistance remains a largely unresolved topic. We have shown previously that mutations distal to the active site are able to perturb binding of darunavir (DRV) via the protein's internal hydrogen-bonding network. In this study, we show that mutations distal to the active site, regardless of context, can play an interdependent role in drug resistance. Applying eigenvalue decomposition to collections of hydrogen bonding and van der Waals interactions from a series of molecular dynamics simulations of 15 diverse HIV-1 protease variants, we identify sites in the protease where amino acid substitutions lead to perturbations in nonbonded interactions with DRV and/or the hydrogen-bonding network of the protease itself. While primary mutations are known to drive resistance in HIV-1 protease, these findings delineate the significant contributions of accessory mutations to resistance. Identifying the variable positions in the protease that have the greatest impact on drug resistance may aid in future structure-based design of inhibitors.

An approach to creating a more realistic working model from a protein data bank entry.

Science.gov (United States)

Brandon, Christopher J; Martin, Benjamin P; McGee, Kelly J; Stewart, James J P; Braun-Sand, Sonja B

2015-01-01

An accurate model of three-dimensional protein structure is important in a variety of fields such as structure-based drug design and mechanistic studies of enzymatic reactions. While the entries in the Protein Data Bank ( http://www.pdb.org ) provide valuable information about protein structures, a small fraction of the PDB structures were found to contain anomalies not reported in the PDB file. The semiempirical PM7 method in MOPAC2012 was used for identifying anomalously short hydrogen bonds, C-H⋯O/C-H⋯N interactions, non-bonding close contacts, and unrealistic covalent bond lengths in recently published Protein Data Bank files. It was also used to generate new structures with these faults removed. When the semiempirical models were compared to those of PDB_REDO (http://www.cmbi.ru.nl/pdb_redo/), the clashscores, as defined by MolProbity ( http://molprobity.biochem.duke.edu/), were better in about 50% of the structures. The semiempirical models also had a lower root-mean-square-deviation value in nearly all cases than those from PDB_REDO, indicative of a better conservation of the tertiary structure. Finally, the semiempirical models were found to have lower clashscores than the initial PDB file in all but one case. Because this approach maintains as much of the original tertiary structure as possible while improving anomalous interactions, it should be useful to theoreticians, experimentalists, and crystallographers investigating the structure and function of proteins.

Modification of microstructure and electrical conductivity of plasma-sprayed YSZ deposit through post-densification process

International Nuclear Information System (INIS)

Ning Xianjin; Li Chengxin; Li Changjiu; Yang Guanjun

2006-01-01

4.5 mol% yttria-stabilized zirconia (YSZ) coating was deposited by atmospheric plasma spraying (APS) as an electrolyte for solid oxide fuel cells (SOFCs) applications. The post treatment was employed using zirconium and yttrium nitrate solution infiltration to densify the coating microstructure for improvement of gas permeability. The deposition of YSZ through nitrate in voids of the coating was examined. Microstructure of the as-sprayed and densified coatings was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of infiltrating treatment on coating microstructure and electrical conductivity was examined. The electrical conductivity of APS-sprayed YSZ coating at the direction perpendicular to coating surface was much lower than that of bulk materials. Post-densification treatment improved the electrical conductivity of YSZ coating by about 25% compared with as-sprayed coating. It was found that the deposition of YSZ resulting from decomposition of nitrate in the lamellar interface gaps was different from that in vertical cracks in lamella owing to the orthogonal feature of those two types of gaps. The nanopores were formed in the deposited YSZ in nonbonded interface gaps while large pores were residued in vertical cracks in splats. The microstructural examination suggests that nanopores in the deposited YSZ in nonbonded interfaces in the coating were isolated from each other, which led to the significant reduction of gas permeability after densification. Moreover, the nanocontacts between lamellae resulted in high contact resistance and limit improvement of electrical conductivity of the coating after densification

Defaunation leads to interaction deficits, not interaction compensation, in an island seed dispersal network.

Science.gov (United States)

Fricke, Evan C; Tewksbury, Joshua J; Rogers, Haldre S

2018-01-01

Following defaunation, the loss of interactions with mutualists such as pollinators or seed dispersers may be compensated through increased interactions with remaining mutualists, ameliorating the negative cascading impacts on biodiversity. Alternatively, remaining mutualists may respond to altered competition by reducing the breadth or intensity of their interactions, exacerbating negative impacts on biodiversity. Despite the importance of these responses for our understanding of the dynamics of mutualistic networks and their response to global change, the mechanism and magnitude of interaction compensation within real mutualistic networks remains largely unknown. We examined differences in mutualistic interactions between frugivores and fruiting plants in two island ecosystems possessing an intact or disrupted seed dispersal network. We determined how changes in the abundance and behavior of remaining seed dispersers either increased mutualistic interactions (contributing to "interaction compensation") or decreased interactions (causing an "interaction deficit") in the disrupted network. We found a "rich-get-richer" response in the disrupted network, where remaining frugivores favored the plant species with highest interaction frequency, a dynamic that worsened the interaction deficit among plant species with low interaction frequency. Only one of five plant species experienced compensation and the other four had significant interaction deficits, with interaction frequencies 56-95% lower in the disrupted network. These results do not provide support for the strong compensating mechanisms assumed in theoretical network models, suggesting that existing network models underestimate the prevalence of cascading mutualism disruption after defaunation. This work supports a mutualist biodiversity-ecosystem functioning relationship, highlighting the importance of mutualist diversity for sustaining diverse and resilient ecosystems. © 2017 John Wiley & Sons Ltd.

Final LDRD report :

Energy Technology Data Exchange (ETDEWEB)

Ambrosini, Andrea; Miller, James Edward; Allendorf, Mark D.; Coker, Eric Nicholas; Ermanoski, Ivan; Hogan, Roy E.,; McDaniel, Anthony H.

2014-01-01

Despite rapid progress, solar thermochemistry remains high risk; improvements in both active materials and reactor systems are needed. This claim is supported by studies conducted both prior to and as part of this project. Materials offer a particular large opportunity space as, until recently, very little effort apart from basic thermodynamic analysis was extended towards understanding this most fundamental component of a metal oxide thermochemical cycle. Without this knowledge, system design was hampered, but more importantly, advances in these crucial materials were rare and resulted more from intuition rather than detailed insight. As a result, only two basic families of potentially viable solid materials have been widely considered, each of which has significant challenges. Recent efforts towards applying an increased level of scientific rigor to the study of thermochemical materials have provided a much needed framework and insights toward developing the next generation of highly improved thermochemically active materials. The primary goal of this project was to apply this hard-won knowledge to rapidly advance the field of thermochemistry to produce a material within 2 years that is capable of yielding CO from CO2 at a 12.5 % reactor efficiency. Three principal approaches spanning a range of risk and potential rewards were pursued: modification of known materials, structuring known materials, and identifying/developing new materials for the application. A newly developed best-of-class material produces more fuel (9x more H2, 6x more CO) under milder conditions than the previous state of the art. Analyses of thermochemical reactor and system efficiencies and economics were performed and a new hybrid concept was reported. The larger case for solar fuels was also further refined and documented.

Theoretical Calculation of Jet Fuel Thermochemistry. 1; Tetrahydrodicylopentadiene (JP10) Thermochemistry Using the CBS-QB3 and G3(MP2)//B3LYP Methods

Science.gov (United States)

Zehe, Michael J.; Jaffe, Richard L.

2010-01-01

High-level ab initio calculations have been performed on the exo and endo isomers of gas-phase tetrahydrodicyclopentadiene (THDCPD), a principal component of the jet fuel JP10, using the Gaussian Gx and Gx(MPx) composite methods, as well as the CBS-QB3 method, and using a variety of isodesmic and homodesmotic reaction schemes. The impetus for this work is to help resolve large discrepancies existing between literature measurements of the formation enthalpy Delta (sub f)H deg (298) for exo-THDCPD. We find that use of the isodesmic bond separation reaction C10H16 + 14CH4 yields 12C2H6 yields results for the exo isomer (JP10) in between the two experimentally accepted values, for the composite methods G3(MP2), G3(MP2)//B3LYP, and CBS-QB3. Application of this same isodesmic bond separation scheme to gas-phase adamantane yields a value for Delta (sub f)H deg (298) within 5 kJ/mol of experiment. Isodesmic bond separation calculations for the endo isomer give a heat of formation in excellent agreement with the experimental measurement. Combining our calculated values for the gas-phase heat of formation with recent measurements of the heat of vaporization yields recommended values for Delta (sub f)H deg (298)liq of -126.4 and -114.7 kJ/mol for the exo and endo isomers, respectively.

Interactive benchmarking

DEFF Research Database (Denmark)

Lawson, Lartey; Nielsen, Kurt

2005-01-01

We discuss individual learning by interactive benchmarking using stochastic frontier models. The interactions allow the user to tailor the performance evaluation to preferences and explore alternative improvement strategies by selecting and searching the different frontiers using directional...... in the suggested benchmarking tool. The study investigates how different characteristics on dairy farms influences the technical efficiency....

Weak interactions with nuclei

International Nuclear Information System (INIS)

Walecka, J.D.

1983-01-01

Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model

Designing for mobile interaction

DEFF Research Database (Denmark)

Nazzi, Elena

2009-01-01

The theme of this PhD project is designing for mobile interaction with devices and services, for the accessing, making, and sharing of information, taking into account the dynamic physical and social settings that embrace this interaction. To narrow down this theme, the whole project focuses...... on the exploitation of social interaction --- in particular among senior citizens --- to enhance and support mobile interaction....

Grasp interaction with tablets

CERN Document Server

Wolf, Katrin

2015-01-01

This book presents guidelines for a future device type: a tablet that allows ergonomic front- and back-of-device interaction. These guidelines help designers and developers of user interfaces to build ergonomic applications for tablet devices, in particular for devices that enable back-of-device interaction. In addition, manufacturers of tablet devices obtain arguments that back-of-device interaction is a promising extension of the interaction design space and results in increased input capabilities, enriched design possibilities, and proven usability. The guidelines are derived from empirical studies and developed to fit the users’ skills to the way the novel device type is held. Three particular research areas that are relevant to develop design guidelines for tablet interaction are investigated: ergonomic gestures, interaction areas, and pointing techniques.

Electromagnetic cellular interactions.

Science.gov (United States)

Cifra, Michal; Fields, Jeremy Z; Farhadi, Ashkan

2011-05-01

Chemical and electrical interaction within and between cells is well established. Just the opposite is true about cellular interactions via other physical fields. The most probable candidate for an other form of cellular interaction is the electromagnetic field. We review theories and experiments on how cells can generate and detect electromagnetic fields generally, and if the cell-generated electromagnetic field can mediate cellular interactions. We do not limit here ourselves to specialized electro-excitable cells. Rather we describe physical processes that are of a more general nature and probably present in almost every type of living cell. The spectral range included is broad; from kHz to the visible part of the electromagnetic spectrum. We show that there is a rather large number of theories on how cells can generate and detect electromagnetic fields and discuss experimental evidence on electromagnetic cellular interactions in the modern scientific literature. Although small, it is continuously accumulating. Copyright © 2010 Elsevier Ltd. All rights reserved.

Discerning molecular interactions: A comprehensive review on biomolecular interaction databases and network analysis tools.

Science.gov (United States)

Miryala, Sravan Kumar; Anbarasu, Anand; Ramaiah, Sudha

2018-02-05

Computational analysis of biomolecular interaction networks is now gaining a lot of importance to understand the functions of novel genes/proteins. Gene interaction (GI) network analysis and protein-protein interaction (PPI) network analysis play a major role in predicting the functionality of interacting genes or proteins and gives an insight into the functional relationships and evolutionary conservation of interactions among the genes. An interaction network is a graphical representation of gene/protein interactome, where each gene/protein is a node, and interaction between gene/protein is an edge. In this review, we discuss the popular open source databases that serve as data repositories to search and collect protein/gene interaction data, and also tools available for the generation of interaction network, visualization and network analysis. Also, various network analysis approaches like topological approach and clustering approach to study the network properties and functional enrichment server which illustrates the functions and pathway of the genes and proteins has been discussed. Hence the distinctive attribute mentioned in this review is not only to provide an overview of tools and web servers for gene and protein-protein interaction (PPI) network analysis but also to extract useful and meaningful information from the interaction networks. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular Innovations Toward Theranostics of Aggressive Prostate Cancer

Science.gov (United States)

2017-11-01

A gg re ga tio n, % Triazine dendrimer concentration, µM G3-NH2 G5-NH2 G7-NH2 Figure 1. Induction of platelet aggregation by amine terminated... behaviour of PEG chains in water.10 The shapes of 3 and 4 differ: 3 appears more spherical/globular while 4 adopts an elongated oval shape. Table 1...approach.20 H is the sum of the total gas -phase in vacuo non-bond energy (DEgas) of the dendrimers and of a solvation term (DGsolv = DGPB + DGNP).21 The

Fragility–structure–conductivity relations in vanadium tellurite glass

DEFF Research Database (Denmark)

Kjeldsen, Jonas; Yue, Yuanzheng; Rodrigues, Ana Candida Martins

the ability to intercalate lithium-ions, it is a candidate as cathode material. Here, we investigate the correlation between liquid fragility, structure and electronic conductivity in a series of vanadium-tellurite glasses with varying vanadium concentration. We measure dynamic and thermodynamic fragility...... the number of bonding and non-bonding oxygen atoms per network former, while we use IS and ESR to determine the electronic conductivity and the valence states of the system. We correlate the changes in local atomic structures as determined by NMR to the observed changes in macroscopic properties. Since...

MULTI: a shared memory approach to cooperative molecular modeling.

Science.gov (United States)

Darden, T; Johnson, P; Smith, H

1991-03-01

A general purpose molecular modeling system, MULTI, based on the UNIX shared memory and semaphore facilities for interprocess communication is described. In addition to the normal querying or monitoring of geometric data, MULTI also provides processes for manipulating conformations, and for displaying peptide or nucleic acid ribbons, Connolly surfaces, close nonbonded contacts, crystal-symmetry related images, least-squares superpositions, and so forth. This paper outlines the basic techniques used in MULTI to ensure cooperation among these specialized processes, and then describes how they can work together to provide a flexible modeling environment.

Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation.

Science.gov (United States)

van Aggelen, Helen; Yang, Yang; Yang, Weitao

2014-05-14

Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H2, and eliminates delocalization errors in H2(+) and other single-bond systems. It gives surprisingly good non-bonded interaction energies--competitive with the ph-RPA--with the correct R(-6) asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.

Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation

International Nuclear Information System (INIS)

Aggelen, Helen van; Yang, Yang; Yang, Weitao

2014-01-01

Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H 2 , and eliminates delocalization errors in H 2 + and other single-bond systems. It gives surprisingly good non-bonded interaction energies – competitive with the ph-RPA – with the correct R −6 asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations

Characteristics of Sulfuric Acid Condensation on Cylinder Liners of Large Two-Stroke Marine Engines

DEFF Research Database (Denmark)

Cordtz, Rasmus Lage; Mayer, Stefan; Schramm, Jesper

. Formation of corrosive sulfuric acid in the cylinder gas is modeled with a cali-brated engine model that incorporates a detailed sulfur reaction mechanism. Condensation of sulfuric acid follows the analogy between heat and mass transfer. Average bulk gas acid dew points are calculated by applying two......-phase thermochemistry of the binary H2O-H2SO4 system. Max dew points of typically more than 200 °C are modeled close to max pressure and variations in terms of operating conditions are not large. However small increments of the dew point provided by e.g. the residual gas fraction, operating pressure, sulfur content...

Development and validation of improved part-models for transient sprays and their combustion; Entwicklung und Validierung verbesserter Teil-Modelle fuer transiente Sprays mit Verbrennung

Energy Technology Data Exchange (ETDEWEB)

Margari, O.-N.

2005-07-01

This yearly report for the Swiss Federal Office of Energy (SFOE) presents a review of experimental work being done at the Laboratory for Aero-thermochemistry and Combustion Systems at the Federal Institute of Technology ETH in Zurich, Switzerland, on the emissions of direct-injection diesel engines. The results of experiments made that investigated the formation of particulate matter (PM) emissions are discussed. The methods used are described, including two optical methods for the volumetric measurement of soot formation. The results obtained from measurements made at various injection pressures ranging from 500 to 1300 bar are discussed. Further work to be done with diesel/butyal mixtures and diesel/water emulsions is discussed.

Flame propagation in two-dimensional solids: Particle-resolved studies with complex plasmas

Science.gov (United States)

Yurchenko, S. O.; Yakovlev, E. V.; Couëdel, L.; Kryuchkov, N. P.; Lipaev, A. M.; Naumkin, V. N.; Kislov, A. Yu.; Ovcharov, P. V.; Zaytsev, K. I.; Vorob'ev, E. V.; Morfill, G. E.; Ivlev, A. V.

2017-10-01

Using two-dimensional (2D) complex plasmas as an experimental model system, particle-resolved studies of flame propagation in classical 2D solids are carried out. Combining experiments, theory, and molecular dynamics simulations, we demonstrate that the mode-coupling instability operating in 2D complex plasmas reveals all essential features of combustion, such as an activated heat release, two-zone structure of the self-similar temperature profile ("flame front"), as well as thermal expansion of the medium and temperature saturation behind the front. The presented results are of relevance for various fields ranging from combustion and thermochemistry, to chemical physics and synthesis of materials.

Chemical reduction of refractory oxides by atomic hydrogen

International Nuclear Information System (INIS)

Dooley, D.; Balooch, M.; Olander, D.R.

1978-11-01

The chemical reduction of UO 2 and Al 2 O 3 by atomic hydrogen was studied. Results of the UO 2 /H investigation indicates that reduction of UO 2 by atomic hydrogen proceeds by the production of water vapor and hypostoichiometric urania. Water vapor and aluminum metal are formed in the Al 2 O 3 /H system. The relative ease which UO 2 is reduced by atomic hydrogen compared with Al 2 O 3 is due to two factors. The first is related to the thermochemistry of the reactions. The second factor which favors efficient reduction of UO 2 but not of Al 2 O 3 is the oxygen diffusivity

Semi-empirical software for the aluminothermic and carbothermic reactions

Directory of Open Access Journals (Sweden)

Milorad Gavrilovski

2014-09-01

Full Text Available Understanding the reaction thermochemistry as well as formatting the empirical data about element distribution in gas-metal-slag phases is essential for creating a good model for aluminothermic and carbothermic reaction. In this paper modeling of material and energy balance of these reactions is described with the algorithm. The software, based on this model is basically made for production of high purity ferro alloys through aluminothermic process and then extended for some carbothermic process. Model validation is demonstrated with production of FeTi, FeW, FeB and FeMo in aluminothermic and reduction of mill scale, pyrite cinders and magnetite fines in carbothermic process.

Formulation of basic principles for innovative combustion and work processes; Projekt Erarbeitung von Grundlagen fuer innovative Brennverfahren und motorische Arbeitsprozesse

Energy Technology Data Exchange (ETDEWEB)

Barroso, G.; Escher, A.; Boulouchos, K. [Eidgenoessische Technische Hochschule (ETH), Labor fuer Aerothermochemie und Verbrennungssysteme IET, ETH-Zentrum, Zuerich (Switzerland)

2004-07-01

This yearly report for 2004 presents a review of work being done on behalf of the Swiss Federal Office of Energy (SFOE) at the Laboratory for Aero-thermochemistry and Combustion Systems at the Federal Institute of Technology ETH in Zurich, Switzerland, on the development of basic principles for innovative combustion and work processes. A successfully-used approach involving reaction-path analysis, heat-release analysis and the optimisation of bio-inspired algorithms is discussed. Experimental investigations made using the high-pressure, high-temperature cell at the ETH are described and initial results are discussed. The commissioning of a one-stroke Rapid Compression Machine EHT and the results of initial experiments are presented.

[National Institute for Petroleum and Energy Research] 1991 annual report, October 1, 1990--September 30, 1991

Energy Technology Data Exchange (ETDEWEB)

1993-05-01

This Annual Report provides research accomplishments, publications, and presentations resulting from the FY91 research conducted under the following Base Program projects: reservoir assessment and characterization; TORIS research support; three-phase relative permeability; imaging techniques applied to the study of fluids in porous media; development of improved microbial flooding methods; development of improved surfactant flooding methods; development of improved alkaline flooding methods; development of improved mobility- control methods; gas flooding; mobility control and sweep improvement in gas flooding; thermal processes for light oil recovery; thermal processes for heavy oil recovery; thermochemistry and thermophysical properties of organic nitrogen- and diheteroatom- containing compounds; and development of analytical methodology for analysis of heavy crudes.

Prediction of Protein-Protein Interactions Related to Protein Complexes Based on Protein Interaction Networks

Directory of Open Access Journals (Sweden)

Peng Liu

2015-01-01

Full Text Available A method for predicting protein-protein interactions based on detected protein complexes is proposed to repair deficient interactions derived from high-throughput biological experiments. Protein complexes are pruned and decomposed into small parts based on the adaptive k-cores method to predict protein-protein interactions associated with the complexes. The proposed method is adaptive to protein complexes with different structure, number, and size of nodes in a protein-protein interaction network. Based on different complex sets detected by various algorithms, we can obtain different prediction sets of protein-protein interactions. The reliability of the predicted interaction sets is proved by using estimations with statistical tests and direct confirmation of the biological data. In comparison with the approaches which predict the interactions based on the cliques, the overlap of the predictions is small. Similarly, the overlaps among the predicted sets of interactions derived from various complex sets are also small. Thus, every predicted set of interactions may complement and improve the quality of the original network data. Meanwhile, the predictions from the proposed method replenish protein-protein interactions associated with protein complexes using only the network topology.

Quantum interaction. Proceedings

International Nuclear Information System (INIS)

Bruza, Peter; Rijsbergen, Keith van

2009-01-01

This book constitutes the refereed proceedings of the Third International Symposium on Quantum Interaction, QI 2009, held in Saarbruecken, Germany, in March 2009. The 21 revised full papers presented together with the 3 position papers were carefully reviewed and selected from numerous submissions. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, decision theory, information retrieval, information systems, social interaction, computational linguistics and finance. (orig.)

Quantum interaction. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Bruza, Peter [Queensland Univ. of Technology, Brisbane (Australia). Faculty of Science and Technology; Sofge, Donald [Navy Center for Applied Research in Artificial Intelligence, Washington, DC (United States). Naval Research Lab.; Lawless, William [Paine Coll., Augusta, GA (United States); Rijsbergen, Keith van [Glasgow Univ. (United Kingdom). Dept. of Computing Science; Klusch, Matthias (eds.) [German Research Center for Artificial Intelligence, Saarbruecken (Germany)

2009-07-01

This book constitutes the refereed proceedings of the Third International Symposium on Quantum Interaction, QI 2009, held in Saarbruecken, Germany, in March 2009. The 21 revised full papers presented together with the 3 position papers were carefully reviewed and selected from numerous submissions. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, decision theory, information retrieval, information systems, social interaction, computational linguistics and finance. (orig.)

Designing Interactions for Learning: Physicality, Interactivity, and Interface Effects in Digital Environments

Science.gov (United States)

Hoffman, Daniel L.

2013-01-01

The purpose of the study is to better understand the role of physicality, interactivity, and interface effects in learning with digital content. Drawing on work in cognitive science, human-computer interaction, and multimedia learning, the study argues that interfaces that promote physical interaction can provide "conceptual leverage"…

Modelling the Interaction Levels in HCI Using an Intelligent Hybrid System with Interactive Agents: A Case Study of an Interactive Museum Exhibition Module in Mexico

Directory of Open Access Journals (Sweden)

Ricardo Rosales

2018-03-01

Full Text Available Technology has become a necessity in our everyday lives and essential for completing activities we typically take for granted; technologies can assist us by completing set tasks or achieving desired goals with optimal affect and in the most efficient way, thereby improving our interactive experiences. This paper presents research that explores the representation of user interaction levels using an intelligent hybrid system approach with agents. We evaluate interaction levels of Human-Computer Interaction (HCI with the aim of enhancing user experiences. We consider the description of interaction levels using an intelligent hybrid system to provide a decision-making system to an agent that evaluates interaction levels when using interactive modules of a museum exhibition. The agents represent a high-level abstraction of the system, where communication takes place between the user, the exhibition and the environment. In this paper, we provide a means to measure the interaction levels and natural behaviour of users, based on museum user-exhibition interaction. We consider that, by analysing user interaction in a museum, we can help to design better ways to interact with exhibition modules according to the properties and behaviour of the users. An interaction-evaluator agent is proposed to achieve the most suitable representation of the interaction levels with the aim of improving user interactions to offer the most appropriate directions, services, content and information, thereby improving the quality of interaction experienced between the user-agent and exhibition-agent.

Derivation of the electric dipole--dipole interaction as an electric hyperfine interaction

International Nuclear Information System (INIS)

Parker, G.W.

1986-01-01

The electric dipole--dipole interaction is derived by assuming that the electron and proton in hydrogen have intrinsic electric dipole moments that interact to give an electric hyperfine interaction. The electric field at the proton due to the electron's presumed dipole moment then gives rise to a contact type term for l = 0 and the normal dipole--dipole term for lnot =0. When combined with our previous derivation of the magnetic hyperfine interaction [Am. J. Phys. 52, 36 (1984)], which used a similar approach, these derivations provide a unified treatment of the interaction of electric and magnetic dipoles. As an application of these results, the product of the electron's and proton's dipole moments is estimated to be less than 10 -29 e 2 cm 2

Non-interacting surface solvation and dynamics in protein-protein interactions

NARCIS (Netherlands)

Visscher, Koen M.; Kastritis, Panagiotis L.|info:eu-repo/dai/nl/315886668; Bonvin, Alexandre M J J|info:eu-repo/dai/nl/113691238

2015-01-01

Protein-protein interactions control a plethora of cellular processes, including cell proliferation, differentiation, apoptosis, and signal transduction. Understanding how and why proteins interact will inevitably lead to novel structure-based drug design methods, as well as design of de novo

Mobile Collocated Interactions

DEFF Research Database (Denmark)

Lucero, Andrés; Clawson, James; Lyons, Kent

2015-01-01

Mobile devices such as smartphones and tablets were originally conceived and have traditionally been utilized for individual use. Research on mobile collocated interactions has been looking at situations in which collocated users engage in collaborative activities using their mobile devices, thus...... going from personal/individual toward shared/multiuser experiences and interactions. However, computers are getting smaller, more powerful, and closer to our bodies. Therefore, mobile collocated interactions research, which originally looked at smartphones and tablets, will inevitably include ever......-smaller computers, ones that can be worn on our wrists or other parts of the body. The focus of this workshop is to bring together a community of researchers, designers and practitioners to explore the potential of extending mobile collocated interactions to the use of wearable devices....

Fibronectin-cell interactions

DEFF Research Database (Denmark)

Couchman, J R; Austria, M R; Woods, A

1990-01-01

Fibronectins are widespread extracellular matrix and body fluid glycoproteins, capable of multiple interactions with cell surfaces and other matrix components. Their structure at a molecular level has been resolved, yet there are still many unanswered questions regarding their biologic activity...... in vivo. Much data suggests that fibronectins may promote extracellular matrix assembly, and cell adhesion to those matrices. However, one outstanding enigma is that fibronectins may, under different circumstances, promote both cell migration and anchorage. An analysis of the interaction of fibroblasts...... with proteolytically derived and purified domains of plasma fibronectin revealed that the type of adhesion and the correlated cytoskeletal organization depended on multiple interactions of fibronectin domains with the cell surface. Human dermal fibroblasts were capable of interacting with the integrin-binding domain...

Chasing Ecological Interactions.

Science.gov (United States)

Jordano, Pedro

2016-09-01

Basic research on biodiversity has concentrated on individual species-naming new species, studying distribution patterns, and analyzing their evolutionary relationships. Yet biodiversity is more than a collection of individual species; it is the combination of biological entities and processes that support life on Earth. To understand biodiversity we must catalog it, but we must also assess the ways species interact with other species to provide functional support for the Tree of Life. Ecological interactions may be lost well before the species involved in those interactions go extinct; their ecological functions disappear even though they remain. Here, I address the challenges in studying the functional aspects of species interactions and how basic research is helping us address the fast-paced extinction of species due to human activities.

Foreign language interactive didactics

Directory of Open Access Journals (Sweden)

Arnaldo Moisés Gómez

2016-06-01

Full Text Available Foreign Language Interactive Didactics is intended for foreign language teachers and would-be teachers since it is an interpretation of the foreign language teaching-learning process is conceived from a reflexive social interaction. This interpretation declares learning based on interactive tasks that provide learners with opportunities to interact meaningfully among them, as a way to develop interactional competence as objective in itself and as a means to obtain communicative competence. Foreign language interactive didactics claims for the unity of reflection and action while learning the language system and using it to communicate, by means of solving problems presented in interactive tasks. It proposes a kind of teaching that is interactive, developmental, collaborative, holist, cognitive, problematizing, reflexive, student centered, humanist, and with a strong affective component that empower the influencing psychological factors in learning. This conception appears in the book: DIDÁCTICA INTERACTIVA DE LENGUAS (2007 y 2010. The book is used as a textbook for the subject of Didactics that is part of the curriculum in language teachers’ formation of all the pedagogical sciences universities, in Spanish teachers’ formation who are not Spanish speaking people at Havana University, and also as a reference book for postgraduate courses, master’s and doctorate’ s degrees.

Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange, and Precipitation Kinetics of NO3 Cancrinite and NO3 Sodalite

International Nuclear Information System (INIS)

Navrotsky, Alexandra; Liu, Qinyuan

2004-01-01

The precipitation of aluminosilicate phases from caustic nuclear wastes has proven to be problematic in a number of processes including radionuclide separations (cementation of columns by aluminosilicate phases), tank emptying (aluminosilicate tank heels), and condensation of wastes in evaporators (aluminosilicate precipitates in the evaporators, providing nucleation sites for growth of critical masses of radioactive actinide salts). In a collaboration between SNL and UCD, we have investigated why and how these phases form, and which conditions favor the formation of which phases. These studies have involved synthesis and characterization of aluminosilicate phases formed using a variety of synthesis techniques, kinetics of precipitation, structural investigations of aluminosilicate phases, thermodynamic calculations of aluminosilicate solubility, calorimetric studies of aluminosilicate precipitation, and a limited investigation of radionuclide partitioning and ion exchange processes (involving typical tank fluid chemistries and these materials). The predominant phases that are observed in the aluminosilicate precipitates from basic tanks wastes (i.e. Hanford, Savannah River Site ''SRS'' wastes) are the salt enclathrated zeolites: sodium nitrate, sodium carbonate and sodium hydroxide sodalite and cancrinite. These phases precipitate readily from the high ionic strength, highly basic solutions at ambient temperatures as well as at elevated temperatures, with or without the presence of an external Al and Si source (both are contained in the waste solutions), and upon interactions with reactive soil components such as clays

Aquaporin Protein-Protein Interactions

Directory of Open Access Journals (Sweden)

Jennifer Virginia Roche

2017-10-01

Full Text Available Aquaporins are tetrameric membrane-bound channels that facilitate transport of water and other small solutes across cell membranes. In eukaryotes, they are frequently regulated by gating or trafficking, allowing for the cell to control membrane permeability in a specific manner. Protein–protein interactions play crucial roles in both regulatory processes and also mediate alternative functions such as cell adhesion. In this review, we summarize recent knowledge about aquaporin protein–protein interactions; dividing the interactions into three types: (1 interactions between aquaporin tetramers; (2 interactions between aquaporin monomers within a tetramer (hetero-tetramerization; and (3 transient interactions with regulatory proteins. We particularly focus on the structural aspects of the interactions, discussing the small differences within a conserved overall fold that allow for aquaporins to be differentially regulated in an organism-, tissue- and trigger-specific manner. A deep knowledge about these differences is needed to fully understand aquaporin function and regulation in many physiological processes, and may enable design of compounds targeting specific aquaporins for treatment of human disease.

Interactive Strategy-Making

DEFF Research Database (Denmark)

Andersen, Torben Juul

2015-01-01

This article outlines an interactive strategy-making model that combines central reasoning with ongoing learning from decentralised responses. The management literature often presents strategy as implementing an optimal plan identified through rational analysis and ascribes potential shortcomings...... to failed communication and execution of the planned actions. However, effective strategy-making comprises both central reasoning from forward-looking planning considerations and decentralised responses to emerging events as interacting elements in a dynamic adaptive system. The interaction between...

Media Facades beyond Interaction

DEFF Research Database (Denmark)

Fritsch, Jonas

2008-01-01

As part of a the research project Digital Urban Living [www.digitalurbanliving.dk], we have taken part in the design of two large-scale installations that employ interactive technologies to facilitate participation and foster social interactions in public, urban settings. We present the two cases......, Aarhus by Light and Projected Poetry, and discuss the future trajectory of our work in this field, as well as some of our findings regarding the challenges of designing large-scale public interactive installations. In doing so, we specifically highlight the possibilities in relation to designing...... for affective experience and engaging interaction that advocate for a long-term interactive experience....

Density dependent effective interactions

International Nuclear Information System (INIS)

Dortmans, P.J.; Amos, K.

1994-01-01

An effective nucleon-nucleon interaction is defined by an optimal fit to select on-and half-off-of-the-energy shell t-and g-matrices determined by solutions of the Lippmann-Schwinger and Brueckner-Bethe-Goldstone equations with the Paris nucleon-nucleon interaction as input. As such, it is seen to better reproduce the interaction on which it is based than other commonly used density dependent effective interactions. The new (medium modified) effective interaction when folded with appropriate density matrices, has been used to define proton- 12 C and proton- 16 O optical potentials. With them elastic scattering data are well fit and the medium effects identifiable. 23 refs., 8 figs

Electromagnetic current in weak interactions

International Nuclear Information System (INIS)

Ma, E.

1983-01-01

In gauge models which unify weak and electromagnetic interactions, the weak neutral-current interaction also involves the electromagnetic current. The exact nature of such a component can be explored using e + e - experimental data. In recent years, the existence of a new component of the weak interaction has become firmly established, i.e., the neutral-current interaction. As such, it competes with the electromagnetic interaction whenever the particles involved are also charged, but at a very much lower rate because its effective strength is so small. Hence neutrino processes are best for the detection of the neutral-current interaction. However, in any gauge model which unifies weak and electromagnetic interactions, the weak neutral-current interaction also involves the electromagnetic current

Interaction Widget

DEFF Research Database (Denmark)

Ingstrup, Mads

2003-01-01

This pattern describes the idea of making a user interface of discrete, reusable entities---here called interaction widgets. The idea behind widgets is described using two perspectives, that of the user and that of the developer. It is the forces from these two perspectives that are balanced...... in the pattern. The intended audience of the pattern is developers and researchers within the field of human computer interaction....

Superconductivity in a Fermi liquid from repulsive interactions: The role of electron–phonon interaction

International Nuclear Information System (INIS)

Fan, J.D.; Malozovsky, Y.M.

2013-01-01

Highlights: • The sign reversal of pair interaction in momentum space is proved. • It is also shown that electron-phonon interaction in fact leads to the pairing-break effect. • Transition temperature into superconductivity depends on competition between electron-phonon and Coulomb interactions. • Calculated exponent α of the isotope effect shows the possibility equal to, greater or less than 0.5, and even negative. -- Abstract: Based on our previously proven theorem that the interaction between a pair of quasiparticles in the normal Fermi liquid has an opposite sign to the interaction between particles, we consider pair correlation between a pair of quasiparticles when the interaction between particles is repulsive. For the convenience of statements, we have presented in this article once again the proof of the theorem in terms of an exact equation for the thermodynamic potential due to interaction between particles and based on the Green’s function method. Further, we have derived the Landau expansion of the thermodynamic potentials in terms of the variation of the quasiparticle distribution function. We have also derived the expansion of the thermodynamic potential in terms of the variation of an exact single particle (not quasiparticles), these derivations lead to the relationship between the interaction function for two quasiparticles and the interaction energy between two particles as shown. According to the proven theorem the interaction between a pair of quasiparticles is attractive in this case, the pairing – Cooper’s pairing between a pair of quasiparticles is possible. We solve the Bethe–Salpeter type equation for paring of two quasiparticles when both interactions – the Coulomb repulsive and electron–phonon interaction are present. We show that the electron–phonon interaction, in fact, leads to the pair breaking effect, in contrast to the common belief that electron–phonon interaction is the main mechanism for Cooper’s pair

Interactive cinema : engagement and interaction

NARCIS (Netherlands)

Vosmeer, M.; Schouten, B.; Mitchell, A.

2014-01-01

Technologies that were initially developed to be applied within the domain of video games are currently being used in experiments to explore their meaning and possibilities for cinema and cinema audiences. In this position paper we examine how narrativity, interactivity and engagement are mutually

Interaction as Negotiation

DEFF Research Database (Denmark)

Kristensen, Jannie Friis; Nielsen, Christina

In this paper we discuss recent developments in interaction design principles for ubiquitous computing environments, specifically implications related to situated and mobile aspects of work. We present 'Interaction through Negotiation' as a general Human-Computer Interaction (HCI) paradigm, aimed...... at ubiquitous/pervasive technology and environments, with focus on facilitating negotiation in and between webs of different artifacts, humans and places. This approach is concerned with the way technology presents itself to us, both as physical entities and as conceptual entities, as well as the relations...... on several extensive empirical case studies, as well as co-operative design-sessions, we present a reflective analysis providing insights into results of the "Interaction through Negotiation" design approach in action. A very promising area of application is exception handling in pervasive computing...

Air-Sea Interaction

Science.gov (United States)

Csanady, G. T.

2001-03-01

In recent years air-sea interaction has emerged as a subject in its own right, encompassing small-scale and large-scale processes in both air and sea. Air-Sea Interaction: Laws and Mechanisms is a comprehensive account of how the atmosphere and the ocean interact to control the global climate, what physical laws govern this interaction, and its prominent mechanisms. The topics covered range from evaporation in the oceans, to hurricanes, and on to poleward heat transport by the oceans. By developing the subject from basic physical (thermodynamic) principles, the book is accessible to graduate students and research scientists in meteorology, oceanography, and environmental engineering. It will also be of interest to the broader physics community involved in the treatment of transfer laws, and thermodynamics of the atmosphere and ocean.

Quark-quark interactions

International Nuclear Information System (INIS)

Jacob, M.

1982-01-01

This chapter discusses interactions only at the constituent level, as observed in hadron-hadron collisions. It defines quarks and gluons as constituents of the colliding hadrons, reviews some applications of perturbative OCD, discussing in turn lepton pair production, which in lowest order approximation corresponds to the Drell-Yan process. It investigates whether quark-quark interactions could not lead to some new color structure different from those prevalent for known baryons and mesons, which could be created in hadron interactions, and whether color objects (not specifically quarks or gluons) could not appear as free particles. Discussed is perturbative QCD in hadron collisions; the quark approach to soft processes; and new color structures. It points out that perturbative QCD has been at the origin of much progress in the understanding of hadron interactions at the constituent level

On topological RNA interaction structures.

Science.gov (United States)

Qin, Jing; Reidys, Christian M

2013-07-01

Recently a folding algorithm of topological RNA pseudoknot structures was presented in Reidys et al. (2011). This algorithm folds single-stranded γ-structures, that is, RNA structures composed by distinct motifs of bounded topological genus. In this article, we set the theoretical foundations for the folding of the two backbone analogues of γ structures: the RNA γ-interaction structures. These are RNA-RNA interaction structures that are constructed by a finite number of building blocks over two backbones having genus at most γ. Combinatorial properties of γ-interaction structures are of practical interest since they have direct implications for the folding of topological interaction structures. We compute the generating function of γ-interaction structures and show that it is algebraic, which implies that the numbers of interaction structures can be computed recursively. We obtain simple asymptotic formulas for 0- and 1-interaction structures. The simplest class of interaction structures are the 0-interaction structures, which represent the two backbone analogues of secondary structures.

Thermochemistry of the Dissolution of Dipeptides Containing DL-α-Alanine in Aqueous Solutions of Sodium Dodecyl Sulfate at 298.15 K

Science.gov (United States)

Smirnov, V. I.; Badelin, V. G.

2018-05-01

Enthalpies of the dissolution of DL-α-alanylglycine (AlaGly), DL-α-alanyl-DL-α-alanine (AlaAla), DL-α-alanyl-DL-α-valine (AlaVal), and DL-α-alanyl-DL-norleucine (AlaNln) in an aqueous solution of sodium dodecyl sulfate (SDS) at SDS concentration of m = 0-0.07 mol kg-1 and temperature T = 298.15 K are measured via calorimetry. The standard values of the enthalpy of dissolution (Δsol H m ) and the transfer of dipeptides (Δtr H m ) from water to aqueous SDS solutions are calculated using the experimental data. The dependences of Δsol H m and Δtr H m the SDS concentration at a constant concentration of dipeptide are established. Thermochemical characteristics of the transfer of AlaGly, AlaAla, AlaVal, and AlaNln in the investigated range of SDS concentrations are compared. The results are interpreted by considering ion-ion, ion-polar, and hydrophobic-hydrophobic interactions between SDS and dipeptide molecules.

An Interactive Tool for Creating Multi-Agent Systems and Interactive Agent-based Games

DEFF Research Database (Denmark)

Lund, Henrik Hautop; Pagliarini, Luigi

2011-01-01

Utilizing principles from parallel and distributed processing combined with inspiration from modular robotics, we developed the modular interactive tiles. As an educational tool, the modular interactive tiles facilitate the learning of multi-agent systems and interactive agent-based games...

Associations of Low-Income Working Mothers' Daily Interactions with Supervisors and Mother-Child Interactions

Science.gov (United States)

Gassman-Pines, Anna

2011-01-01

This study investigated associations of low-income working mothers' daily interactions with supervisors and their interactions with children. Sixty-one mothers of preschool-aged children were asked to report on their interactions with their supervisors at work and their interactions with children for 2 weeks (N = 520 workdays). Results show…

Topology and weights in a protein domain interaction network--a novel way to predict protein interactions.

Science.gov (United States)

Wuchty, Stefan

2006-05-23

While the analysis of unweighted biological webs as diverse as genetic, protein and metabolic networks allowed spectacular insights in the inner workings of a cell, biological networks are not only determined by their static grid of links. In fact, we expect that the heterogeneity in the utilization of connections has a major impact on the organization of cellular activities as well. We consider a web of interactions between protein domains of the Protein Family database (PFAM), which are weighted by a probability score. We apply metrics that combine the static layout and the weights of the underlying interactions. We observe that unweighted measures as well as their weighted counterparts largely share the same trends in the underlying domain interaction network. However, we only find weak signals that weights and the static grid of interactions are connected entities. Therefore assuming that a protein interaction is governed by a single domain interaction, we observe strong and significant correlations of the highest scoring domain interaction and the confidence of protein interactions in the underlying interactions of yeast and fly. Modeling an interaction between proteins if we find a high scoring protein domain interaction we obtain 1, 428 protein interactions among 361 proteins in the human malaria parasite Plasmodium falciparum. Assessing their quality by a logistic regression method we observe that increasing confidence of predicted interactions is accompanied by high scoring domain interactions and elevated levels of functional similarity and evolutionary conservation. Our results indicate that probability scores are randomly distributed, allowing to treat static grid and weights of domain interactions as separate entities. In particular, these finding confirms earlier observations that a protein interaction is a matter of a single interaction event on domain level. As an immediate application, we show a simple way to predict potential protein interactions

Restricted Variance Interaction Effects

DEFF Research Database (Denmark)

Cortina, Jose M.; Köhler, Tine; Keeler, Kathleen R.

2018-01-01

Although interaction hypotheses are increasingly common in our field, many recent articles point out that authors often have difficulty justifying them. The purpose of this article is to describe a particular type of interaction: the restricted variance (RV) interaction. The essence of the RV int...

Elastic interactions between hydrogen atoms in metals. II. Elastic interaction energies

International Nuclear Information System (INIS)

Shirley, A.I.; Hall, C.K.

1986-01-01

The fully harmonic lattice approximation derived in a previous paper is used to calculate the elastic interaction energies in the niobium-hydrogen system. The permanent-direct, permanent-indirect, induced-direct, and induced-indirect forces calculated previously each give rise to a corresponding elastic interaction between hydrogen atoms. The latter three interactions have three- and four-body terms in addition to the usual two-body terms. These quantities are calculated and compared with the corresponding two-body permanent elastic interactions obtained in the harmonic-approximation treatment of Horner and Wagner. The results show that the total induced elastic energy is approximately (1/3) the size of the total permanent elastic energy and opposite to it in sign. The total elastic energy due to three-body interactions is approximately (1/4) the size of the total two-body elastic energy, while the total four-body elastic energy is approximately 5% of the total two-body energy. These additional elastic energies are expected to have a profound effect on the thermodynamic and phase-change behavior of a metal hydride

Light and noise pollution interact to disrupt interspecific interactions.

Science.gov (United States)

McMahon, Taegan A; Rohr, Jason R; Bernal, Ximena E

2017-05-01

Studies on the consequences of urbanization often examine the effects of light, noise, and heat pollution independently on isolated species providing a limited understanding of how these combined stressors affect species interactions. Here, we investigate how these factors interact to affect parasitic frog-biting midges (Corethrella spp.) and their túngara frog (Engystomops pustulosus) hosts. A survey of túngara frog calling sites revealed that frog abundance was not significantly correlated with urbanization, light, noise, or temperature. In contrast, frog-biting midges were sensitive to light pollution and noise pollution. Increased light intensity significantly reduced midge abundance at low noise levels. At high noise intensity, there were no midges regardless of light level. Two field experiments controlling light and noise levels to examine attraction of the midges to their host and their feeding behavior confirmed the causality of these field patterns. These findings demonstrate that both light and noise pollution disrupt this host-parasite interaction and highlight the importance of considering interactions among species and types of pollutants to accurately assess the impacts of urbanization on ecological communities. © 2017 by the Ecological Society of America.

Species interactions and plant polyploidy.

Science.gov (United States)

Segraves, Kari A; Anneberg, Thomas J

2016-07-01

Polyploidy is a common mode of speciation that can have far-reaching consequences for plant ecology and evolution. Because polyploidy can induce an array of phenotypic changes, there can be cascading effects on interactions with other species. These interactions, in turn, can have reciprocal effects on polyploid plants, potentially impacting their establishment and persistence. Although there is a wealth of information on the genetic and phenotypic effects of polyploidy, the study of species interactions in polyploid plants remains a comparatively young field. Here we reviewed the available evidence for how polyploidy may impact many types of species interactions that range from mutualism to antagonism. Specifically, we focused on three main questions: (1) Does polyploidy directly cause the formation of novel interactions not experienced by diploids, or does it create an opportunity for natural selection to then form novel interactions? (2) Does polyploidy cause consistent, predictable changes in species interactions vs. the evolution of idiosyncratic differences? (3) Does polyploidy lead to greater evolvability in species interactions? From the scarce evidence available, we found that novel interactions are rare but that polyploidy can induce changes in pollinator, herbivore, and pathogen interactions. Although further tests are needed, it is likely that selection following whole-genome duplication is important in all types of species interaction and that there are circumstances in which polyploidy can enhance the evolvability of interactions with other species. © 2016 Botanical Society of America.

Interaction Design for Public Spaces

DEFF Research Database (Denmark)

Kortbek, Karen Johanne

2008-01-01

In this abstract I describe the doctorial research project "Interaction Design for Public Spaces". The objective of the project is to explore and design interaction contexts in culture related public spaces such as museums, experience centres and festivals. As a perspective on this domain, I...... will focus on the usage of the body as an interaction device. Furthermore, the project will involve a dramaturgic take on communication and design of interactive systems in the pursuit of new ways to stage the interactive contexts. The outcome of the project will be guidelines and conceptual frameworks which...... will help interaction designers when designing for bodily movement, and communicating and staging interactive content in public spaces....

Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?

Energy Technology Data Exchange (ETDEWEB)

Sylvetsky, Nitai, E-mail: gershom@weizmann.ac.il; Martin, Jan M. L., E-mail: gershom@weizmann.ac.il [Department of Organic Chemistry, Weizmann Institute of Science, 76100 Rehovot (Israel); Peterson, Kirk A., E-mail: kipeters@wsu.edu [Department of Chemistry, Washington State University, Pullman, Washington 99164-4630 (United States); Karton, Amir, E-mail: amir.karton@uwa.edu.au [School of Chemistry and Biochemistry, The University of Western Australia, Perth, WA 6009 (Australia)

2016-06-07

In the context of high-accuracy computational thermochemistry, the valence coupled cluster with all singles and doubles (CCSD) correlation component of molecular atomization energies presents the most severe basis set convergence problem, followed by the (T) component. In the present paper, we make a detailed comparison, for an expanded version of the W4-11 thermochemistry benchmark, between, on the one hand, orbital-based CCSD/AV{5,6}Z + d and CCSD/ACV{5,6}Z extrapolation, and on the other hand CCSD-F12b calculations with cc-pVQZ-F12 and cc-pV5Z-F12 basis sets. This latter basis set, now available for H–He, B–Ne, and Al–Ar, is shown to be very close to the basis set limit. Apparent differences (which can reach 0.35 kcal/mol for systems like CCl{sub 4}) between orbital-based and CCSD-F12b basis set limits disappear if basis sets with additional radial flexibility, such as ACV{5,6}Z, are used for the orbital calculation. Counterpoise calculations reveal that, while total atomization energies with V5Z-F12 basis sets are nearly free of BSSE, orbital calculations have significant BSSE even with AV(6 + d)Z basis sets, leading to non-negligible differences between raw and counterpoise-corrected extrapolated limits. This latter problem is greatly reduced by switching to ACV{5,6}Z core-valence basis sets, or simply adding an additional zeta to just the valence orbitals. Previous reports that all-electron approaches like HEAT (high-accuracy extrapolated ab-initio thermochemistry) lead to different CCSD(T) limits than “valence limit + CV correction” approaches like Feller-Peterson-Dixon and Weizmann-4 (W4) theory can be rationalized in terms of the greater radial flexibility of core-valence basis sets. For (T) corrections, conventional CCSD(T)/AV{Q,5}Z + d calculations are found to be superior to scaled or extrapolated CCSD(T)-F12b calculations of similar cost. For a W4-F12 protocol, we recommend obtaining the Hartree-Fock and valence CCSD components from CCSD-F12b

Gestalt Interactional Groups

Science.gov (United States)

Harman, Robert L.; Franklin, Richard W.

1975-01-01

Gestalt therapy in groups is not limited to individual work in the presence of an audience. Describes several ways to involve gestalt groups interactionally. Interactions described focus on learning by doing and discovering, and are noninterpretive. (Author/EJT)

Gaze Interactive Building Instructions

DEFF Research Database (Denmark)

Hansen, John Paulin; Ahmed, Zaheer; Mardanbeigi, Diako

We combine eye tracking technology and mobile tablets to support hands-free interaction with digital building instructions. As a proof-of-concept we have developed a small interactive 3D environment where one can interact with digital blocks by gaze, keystroke and head gestures. Blocks may be moved...

Magnetic interactions between nanoparticles

DEFF Research Database (Denmark)

Mørup, Steen; Hansen, Mikkel Fougt; Frandsen, Cathrine

2010-01-01

We present a short overview of the influence of inter-particle interactions on the properties of magnetic nanoparticles. Strong magnetic dipole interactions between ferromagnetic or ferrimagnetic particles, that would be superparamagnetic if isolated, can result in a collective state...... of nanoparticles. This collective state has many similarities to spin-glasses. In samples of aggregated magnetic nanoparticles, exchange interactions are often important and this can also lead to a strong suppression of superparamagnetic relaxation. The temperature dependence of the order parameter in samples...... of strongly interacting hematite nanoparticles or goethite grains is well described by a simple mean field model. Exchange interactions between nanoparticles with different orientations of the easy axes can also result in a rotation of the sub-lattice magnetization directions....

Plasma-wall interactions

International Nuclear Information System (INIS)

Behrisch, Rainer

1978-01-01

The plasma wall interactions for two extreme cases, the 'vacuum model' and the 'cold gas blanket' are outlined. As a first step for understanding the plasma wall interactions the elementary interaction processes at the first wall are identified. These are energetic ion and neutral particle trapping and release, ion and neutral backscattering, ion sputtering, desorption by ions, photons and electrons and evaporation. These processes have only recently been started to be investigated in the parameter range of interest for fusion research. The few measured data and their extrapolation into regions not yet investigated are reviewed

Interactive governance

DEFF Research Database (Denmark)

Sørensen, Eva; Torfing, Jacob; Peters, B. Guy

Governance has become one of the most commonly used concepts in contemporary political science. It is, however, often used to mean a variety of different things. This book helps to clarify this conceptual muddle by concentrating on one variety of governance-interactive governance. The authors argue...... that although the state may remain important for many aspects of governing, interactions between state and society represent an important, and perhaps increasingly important, dimension of governance. These interactions may be with social actors such as networks, with market actors or with other governments......, but all these forms represent means of governing involving mixtures of state action with the actions of other entities.This book explores thoroughly this meaning of governance, and links it to broader questions of governance. In the process of explicating this dimension of governance the authors also...

Photon-photon interactions

International Nuclear Information System (INIS)

Gilman, F.J.

1980-01-01

A brief summary of the present status of photon-photon interactions is presented. Stress is placed on the use of two-photon collisions to test present ideas on the quark constituents of hadrons and on the theory of strong interactions

Multi-functionalized naphthalene complexes for hydrogen storage

International Nuclear Information System (INIS)

Kalamse, Vijayanand; Wadnerkar, Nitin; Chaudhari, Ajay

2013-01-01

A density functional study of hydrogen uptake capacity of multi-functionalized naphthalene with Ti and Li metal atom has been carried out. It is observed that, the naphthalene functionalized with two Ti atoms can interact with total eight hydrogen molecules in which each Ti metal atom interacts with four hydrogen molecules. Naphthalene decorated with two Li atoms can interact with total three H 2 molecules only. First ( 19 Li) and second ( 20 Li) Li atom can interact with only one and two hydrogen molecule respectively. It is observed that, hydrogen molecules bind strongly to the C 10 H 8 Ti 2 complex than C 10 H 8 Li 2 complex. The gravimetric hydrogen uptake capacity of C 10 H 8 Ti 2 and C 10 H 8 Li 2 complex is found to be 6.72 and 3.73 wt% respectively. Moreover, after functionalizing naphthalene with four Li atoms, the uptake capacity is increased to 7.20 wt %. However, the thermochemistry result favors to Ti functionalized naphthalene complex (C 10 H 8 Ti 2 ) for hydrogen storage over Li functionalized naphthalene (both C 10 H 8 Li 2 and C 10 H 8 Li 4 ) complexes. Atom-centered density matrix propagation (ADMP) molecular dynamics simulations have been performed which showed that C 10 H 8 Li 2 and C 10 H 8 Li 4 complex cannot bind single hydrogen molecule at room temperature whereas C 10 H 8 Ti 2 can bind five hydrogen molecules. -- Highlights: ► The gravimetric H 2 uptake capacity of C 10 H 8 Ti 2 complex is 6.72 wt%. ► Uptake capacity of C 10 H 8 Li 2 and C 10 H 8 Li 4 complex is 3.73 and 7.20 wt% respectively. ► C 10 H 8 Ti is more promising material for hydrogen adsorption. ► C 10 H 8 Ti 2 can bind five hydrogen molecules as shown by ADMP-MD results.

Proxemic Mobile Collocated Interactions

DEFF Research Database (Denmark)

Porcheron, Martin; Lucero, Andrés; Quigley, Aaron

2016-01-01

and their digital devices (i.e. the proxemic relationships). Building on the ideas of proxemic interactions, this workshop is motivated by the concept of ‘proxemic mobile collocated interactions’, to harness new or existing technologies to create engaging and interactionally relevant experiences. Such approaches......Recent research on mobile collocated interactions has been looking at situations in which collocated users engage in collaborative activities using their mobile devices. However, existing practices fail to fully account for the culturally-dependent spatial relationships between people...... in exploring proxemics and mobile collocated interactions....

Two interacting Hofstadter butterflies

International Nuclear Information System (INIS)

Barelli, A.; Bellissard, J.; Jacquod, P.

1997-01-01

The problem of two interacting particles in a quasiperiodic potential is addressed. Using analytical and numerical methods, we explore the spectral properties and eigenstates structure from the weak to the strong interaction case. More precisely, a semiclassical approach based on noncommutative geometry techniques is used to understand the intricate structure of such a spectrum. An interaction induced localization effect is furthermore emphasized. We discuss the application of our results on a two-dimensional model of two particles in a uniform magnetic field with on-site interaction. copyright 1997 The American Physical Society

INTERACTIVE LEARNING: ADVANTAGES AND DISADVANTAGES

Directory of Open Access Journals (Sweden)

O. Kustovska

2016-10-01

Full Text Available In the article the use of interactive technologies in the educational process of the university, allowing students to develop innovative thinking, away from stereotypes, develop imagination, communication skills and expertise, intellectual, emotional, motivational and other areas of personality. Implementing the principles of technological learning, interactive educational technology and provides interactive computer learning tools, and interactivity of educational process when the basic conceptual provisions defined training based on interactive communication.

Interaction of the radiation with matter

International Nuclear Information System (INIS)

2013-01-01

This third chapter presents the ionization, excitation, activation and radiation breaking; radiation directly and indirectly ionizing; interaction of the electromagnetic radiation with matter; interaction of neutrons with matter; interaction of radiation directly ionizing with matter; interaction of electrons with matter, interaction of alpha particle with matter; interaction of fission fragments with matter; travel time and integrated processes of interaction: energy dissipation

Diachronic Perspective and Interaction

DEFF Research Database (Denmark)

Marchetti, Emanuela; Valente, Andrea

. An ongoing participatory inquiry is being conducted, to explore deeper forms of learning and communication for historical museums. Our hypothesis is that the diachronic perspective on historical processes, defined as social interaction within the environment through time, is a key missing element....... Although this interaction style may appeal to teachers, as it reminds of school teaching, it has several disadvantages: a dialogue never occurs between adults and children, who listen in silence, hence it becomes hard to evaluate what has being learnt and how deeply, and finally it is not very engaging....... Explorations of more interactive representations of the diachronic perspective, through play and tangible interaction, may foster a dialogue with young visitors. Therefore, a new interactive installation is being designed, intended as a tool to enrich learning, allowing children to experience historical...

Interactive Topology Optimization

DEFF Research Database (Denmark)

Nobel-Jørgensen, Morten

Interactivity is the continuous interaction between the user and the application to solve a task. Topology optimization is the optimization of structures in order to improve stiffness or other objectives. The goal of the thesis is to explore how topology optimization can be used in applications...... on theory of from human-computer interaction which is described in Chapter 2. Followed by a description of the foundations of topology optimization in Chapter 3. Our applications for topology optimization in 2D and 3D are described in Chapter 4 and a game which trains the human intuition of topology...... optimization is presented in Chapter 5. Topology optimization can also be used as an interactive modeling tool with local control which is presented in Chapter 6. Finally, Chapter 7 contains a summary of the findings and concludes the dissertation. Most of the presented applications of the thesis are available...

Interaction Themes in Music Therapy

DEFF Research Database (Denmark)

Holck, Ulla

2006-01-01

Based on a doctoral study, the author presents a type of music therapy interaction called ‘Interaction Themes.’ These are developed from session to session and often appear in music therapy interventions with children with severe functional limitations, especially children with autism. Although...... whose expressions are often difficult to understand. The presented article describes the characteristics and functions of Interaction Themes, compares the phenomenon with music therapy case literature and delimits it in regard to other types of music therapy interaction with this client group....... the Interaction Themes are characterised by a relatively simple and self-generated content, they have an essential function because they contain the child’s and music therapist’s joint interaction history. They make up the context within which it is possible to create meaningful interaction with a client group...

Conducting interactive experiments online.

Science.gov (United States)

Arechar, Antonio A; Gächter, Simon; Molleman, Lucas

2018-01-01

Online labor markets provide new opportunities for behavioral research, but conducting economic experiments online raises important methodological challenges. This particularly holds for interactive designs. In this paper, we provide a methodological discussion of the similarities and differences between interactive experiments conducted in the laboratory and online. To this end, we conduct a repeated public goods experiment with and without punishment using samples from the laboratory and the online platform Amazon Mechanical Turk. We chose to replicate this experiment because it is long and logistically complex. It therefore provides a good case study for discussing the methodological and practical challenges of online interactive experimentation. We find that basic behavioral patterns of cooperation and punishment in the laboratory are replicable online. The most important challenge of online interactive experiments is participant dropout. We discuss measures for reducing dropout and show that, for our case study, dropouts are exogenous to the experiment. We conclude that data quality for interactive experiments via the Internet is adequate and reliable, making online interactive experimentation a potentially valuable complement to laboratory studies.

Hair Interactions

OpenAIRE

Cani , Marie-Paule; Bertails , Florence

2006-01-01

International audience; Processing interactions is one of the main challenges in hair animation. Indeed, in addition to the collisions with the body, an extremely large number of contacts with high friction rates are permanently taking place between individual hair strands. Simulating the latter is essential: without hair self-interactions, strands would cross each other during motion or come to rest at the same location, yielding unrealistic behavior and a visible lack of hair volume. This c...

Real story interaction: The role of global agency in interactive storytelling

NARCIS (Netherlands)

Roth, C.; Vermeulen, I.E.

2012-01-01

Interactive Storytelling (IS) is a promising new entertainment technology synthesizing pre-authored narrative with dynamic user interaction. Research on user experiences in IS is sparse. The current experiment tested whether different player expectations regarding the impact of their actions yield

An Abstract Interaction Concept for Designing Interaction Behaviour of Service Compositions

NARCIS (Netherlands)

Dirgahayu, T.; Quartel, Dick; van Sinderen, Marten J.; Mertins, Kai; Ruggaber, Rainer; Popplewell, Keith; Xu, Xiaofei

2008-01-01

In a service composition, interaction behaviour specifies an information exchange protocol that must be complied with in order to guarantee interoperability between services. Interaction behaviour can be designed using a top-down design approach utilising high abstraction levels to control its

Multiquark interactions

International Nuclear Information System (INIS)

Luk'yanov, V.K.

1984-01-01

To study multiquark interactions (MQI) the data of experiments confirming the presence of 3q, 6q, 12q states in interacting nuclear nucleons, in hadron- and lepton-nuclear processes at high energies and high momentum transfers are considered. Experimental data on cumulative processes pointing to the existence of MQI are analyzed. Two-channel model of a nucleus (the model of interacting nucleons) in the theory of coupled channels is discussed. The behaviour of form factor of deuteron and NQI (6q) contributions to ed scattering as well as deep inelastic scattering on nuclei are studied. The data known as EMC effect are discussed. It is pointed out that introduction of the notion MQI and consideration of a nucleus as a system of nucleons with a low MQI addition will help to explain such processes as cumulative reactions, form factors of a deuteron and light nuclei, deep inelastic scattering on nuclei

Curiosity and Interaction

NARCIS (Netherlands)

Tieben, R.; Bekker, M.M.; Schouten, B.A.M.

2011-01-01

We explore the concepts of curiosity and interaction: how can we elicit curiosity in public spaces through interactive systems? We have developed a model consisting of five curiosity-evoking principles. In an iterative design research approach, we have explored the design implementations of these

Quantity Estimation Of The Interactions

International Nuclear Information System (INIS)

Gorana, Agim; Malkaj, Partizan; Muda, Valbona

2007-01-01

In this paper we present some considerations about quantity estimations, regarding the range of interaction and the conservations laws in various types of interactions. Our estimations are done under classical and quantum point of view and have to do with the interaction's carriers, the radius, the influence range and the intensity of interactions

Bringing Together Interactive Digital Storytelling with Tangible Interaction : Challenges and Opportunities

NARCIS (Netherlands)

Catala, Alejandro; Theune, Mariët; Sylla, Cristina; Ribeiro, Pedro; Nunes, Nuno; Oakley, Ian; Nisi, Valentina

2017-01-01

This workshop aims to explore challenges and potential opportunities in bringing interactive digital storytelling into the realm of tangible and embodied interaction. To this end, experts from both fields are invited to present and discuss their ideas. Besides fostering discussion and potential

Topology and weights in a protein domain interaction network – a novel way to predict protein interactions

Directory of Open Access Journals (Sweden)

Wuchty Stefan

2006-05-01

Full Text Available Abstract Background While the analysis of unweighted biological webs as diverse as genetic, protein and metabolic networks allowed spectacular insights in the inner workings of a cell, biological networks are not only determined by their static grid of links. In fact, we expect that the heterogeneity in the utilization of connections has a major impact on the organization of cellular activities as well. Results We consider a web of interactions between protein domains of the Protein Family database (PFAM, which are weighted by a probability score. We apply metrics that combine the static layout and the weights of the underlying interactions. We observe that unweighted measures as well as their weighted counterparts largely share the same trends in the underlying domain interaction network. However, we only find weak signals that weights and the static grid of interactions are connected entities. Therefore assuming that a protein interaction is governed by a single domain interaction, we observe strong and significant correlations of the highest scoring domain interaction and the confidence of protein interactions in the underlying interactions of yeast and fly. Modeling an interaction between proteins if we find a high scoring protein domain interaction we obtain 1, 428 protein interactions among 361 proteins in the human malaria parasite Plasmodium falciparum. Assessing their quality by a logistic regression method we observe that increasing confidence of predicted interactions is accompanied by high scoring domain interactions and elevated levels of functional similarity and evolutionary conservation. Conclusion Our results indicate that probability scores are randomly distributed, allowing to treat static grid and weights of domain interactions as separate entities. In particular, these finding confirms earlier observations that a protein interaction is a matter of a single interaction event on domain level. As an immediate application, we

Interacting binaries

International Nuclear Information System (INIS)

Eggleton, P.P.; Pringle, J.E.

1985-01-01

This volume contains 15 review articles in the field of binary stars. The subjects reviewed span considerably, from the shortest period of interacting binaries to the longest, symbiotic stars. Also included are articles on Algols, X-ray binaries and Wolf-Rayet stars (single and binary). Contents: Preface. List of Participants. Activity of Contact Binary Systems. Wolf-Rayet Stars and Binarity. Symbiotic Stars. Massive X-ray Binaries. Stars that go Hump in the Night: The SU UMa Stars. Interacting Binaries - Summing Up

Convergence in Multispecies Interactions

OpenAIRE

Bittleston, Leonora Sophia; Pierce, Naomi E.; Ellison, Aaron M.; Pringle, Anne

2016-01-01

The concepts of convergent evolution and community convergence highlight how selective pressures can shape unrelated organisms or communities in similar ways. We propose a related concept, convergent interactions, to describe the independent evolution of multispecies interactions with similar physiological or ecological functions. A focus on convergent interactions clarifies how natural selection repeatedly favors particular kinds of associations among species. Characterizing convergent inter...

Topology of charge density of flucytosine and related molecules and characteristics of their bond charge distributions.

Science.gov (United States)

Murgich, Juan; Franco, Héctor J; San-Blas, Gioconda

2006-08-24

The molecular charge distribution of flucytosine (4-amino-5-fluoro-2-pyrimidone), uracil, 5-fluorouracil, and thymine was studied by means of density functional theory calculations (DFT). The resulting distributions were analyzed by means of the atoms in molecules (AIM) theory. Bonds were characterized through vectors formed with the charge density value, its Laplacian, and the bond ellipticity calculated at the bond critical point (BCP). Within each set of C=O, C-H, and N-H bonds, these vectors showed little dispersion. C-C bonds formed three different subsets, one with a significant degree of double bonding, a second corresponding to single bonds with a finite ellipticity produced by hyperconjugation, and a third one formed by a pure single bond. In N-C bonds, a decrease in bond length (an increase in double bond character) was not reflected as an increase in their ellipticity, as in all C-C bonds studied. It was also found that substitution influenced the N-C, C-O, and C-C bond ellipticity much more than density and its Laplacian at the BCP. The Laplacian of charge density pointed to the existence of both bonding and nonbonding maxima in the valence shell charge concentration of N, O, and F, while only bonding ones were found for the C atoms. The nonbonding maxima related to the sites for electrophilic attack and H bonding in O and N, while sites of nucleophilic attack were suggested by the holes in the valence shell of the C atoms of the carbonyl groups.

On plasma-neutral gas interaction

International Nuclear Information System (INIS)

Venkataramani, N.; Mattoo, S.K.

1980-01-01

The importance of plasma-neutral gas interaction layer has been emphasized by pointing out its application to a wide variety of physical phenomena. The interaction of a magnetised plasma stream penetrating a neutral gas cloud is discussed in the light of Alfven's critical velocity and Varma's threshold velocity on the ionising interaction. Interaction of a moving magnetised plasma with a stationary neutral gas has been studied and described. The device comprises of a plasma gun and an interaction region where neutral gas cloud is injected. The interaction region is provided with a transverse magnetic field of upto 1000 G. Several diagnostics deployed at the interaction region to make measurements on the macroscopic parameters of plasma and neutral gas are described. The parameters of discharge circuits are measured with high current and voltage probes. An interaction between a magnetised plasma stream and a neutral gas cloud is demonstrated. It is shown that this interaction does not have Varma's threshold on their relative velocity. The Alfven's critical velocity phenomenon is shown to depend on the integrated column neutral gas density that a plasma stream encounters while penetrating through it and not on the neutral gas density in the range of 10 17 -10 21 m -3 . (auth.)

Vortex dynamics during blade-vortex interactions

Science.gov (United States)

Peng, Di; Gregory, James W.

2015-05-01

Vortex dynamics during parallel blade-vortex interactions (BVIs) were investigated in a subsonic wind tunnel using particle image velocimetry (PIV). Vortices were generated by applying a rapid pitch-up motion to an airfoil through a pneumatic system, and the subsequent interactions with a downstream, unloaded target airfoil were studied. The blade-vortex interactions may be classified into three categories in terms of vortex behavior: close interaction, very close interaction, and collision. For each type of interaction, the vortex trajectory and strength variation were obtained from phase-averaged PIV data. The PIV results revealed the mechanisms of vortex decay and the effects of several key parameters on vortex dynamics, including separation distance (h/c), Reynolds number, and vortex sense. Generally, BVI has two main stages: interaction between vortex and leading edge (vortex-LE interaction) and interaction between vortex and boundary layer (vortex-BL interaction). Vortex-LE interaction, with its small separation distance, is dominated by inviscid decay of vortex strength due to pressure gradients near the leading edge. Therefore, the decay rate is determined by separation distance and vortex strength, but it is relatively insensitive to Reynolds number. Vortex-LE interaction will become a viscous-type interaction if there is enough separation distance. Vortex-BL interaction is inherently dominated by viscous effects, so the decay rate is dependent on Reynolds number. Vortex sense also has great impact on vortex-BL interaction because it changes the velocity field and shear stress near the surface.

Spin-orbit interaction induced anisotropic property in interacting quantum wires

Directory of Open Access Journals (Sweden)

Chang Kai

2011-01-01

Full Text Available We investigate theoretically the ground state and transport property of electrons in interacting quantum wires (QWs oriented along different crystallographic directions in (001 and (110 planes in the presence of the Rashba spin-orbit interaction (RSOI and Dresselhaus SOI (DSOI. The electron ground state can cross over different phases, e.g., spin density wave, charge density wave, singlet superconductivity, and metamagnetism, by changing the strengths of the SOIs and the crystallographic orientation of the QW. The interplay between the SOIs and Coulomb interaction leads to the anisotropic dc transport property of QW which provides us a possible way to detect the strengths of the RSOI and DSOI. PACS numbers: 73.63.Nm, 71.10.Pm, 73.23.-b, 71.70.Ej

The two-brain approach: how can mutually interacting brains teach us something about social interaction?

Directory of Open Access Journals (Sweden)

Ivana eKonvalinka

2012-07-01

Full Text Available Measuring brain activity simultaneously from two people interacting is intuitively appealing if one is interested in putative neural markers of social interaction. However, given the complex nature of two-person interactions, it has proven difficult to carry out two-person brain imaging experiments in a methodologically feasible and conceptually relevant way. Only a small number of recent studies have put this into practice, using fMRI, EEG, or NIRS. Here, we review two main two-brain methodological approaches, each with two conceptual strategies. The first group has employed simultaneous fMRI recordings, studying a turn-based interactions on the order of seconds, or b pseudo-interactive scenarios, where only one person is scanned at a time, investigating the flow of information between brains. The second group of studies has recorded dual EEG/NIRS from two people interacting, in a face-to-face turn-based interactions, investigating functional connectivity between theory-of-mind regions of interacting partners, or in b continuous mutual interactions on millisecond timescales, to measure coupling between the activity in one person’s brain and the activity in the other’s brain. We discuss the questions these approaches have addressed, and consider scenarios when simultaneous two-brain recordings are needed. Furthermore, we suggest that a quantification of inter-personal neural effects via measures of emergence, and b multivariate decoding models that generalize source-specific features of interaction, may provide novel tools to study brains in interaction. This may allow for a better understanding of social cognition as both representation and participation.

Communicating Art through Interactive Technology: New Approaches for Interaction Design in Art Museums

DEFF Research Database (Denmark)

Kortbek, Karen Johanne; Grønbæk, Kaj

2008-01-01

This paper discusses new approaches to interaction design for communication of art in the physical museum space. In contrast to the widespread utilization of interactive tech­nologies in cultural heritage and natural science museums it is generally a challenge to introduce technology in art museums...... without disturbing the domain of the art works. To explore the possibilities of communicating art through the use of technology, and to minimize disturbance of the artworks, we apply four main approaches in the communication: 1) gentle audio augmentation of art works; 2) conceptual affinity of art works...... and remote interactive installations; 3) using the body as an interaction device; 4) consistent audio-visual cues for interaction opportunities. The paper describes the application of these approaches for communication of inspira­tional material for a Mariko Mori exhibition. The installations are described...

Interaction of atmospheric pollutants

Energy Technology Data Exchange (ETDEWEB)

Bustueva, K A; Sanotsky, I V

1975-01-01

In evaluating the health effects of chemical and physical factors, it is of great importance to know the possible interactions between different pollutants. The biological effects of interactions, when present, may be synergistic, antagonistic or additive. Each type of interaction calls for a different evaluation and different practical measures. As yet the understanding of such effects is not clear, probably because of differing definitions of terminology. For example, the combined effect of sulfur dioxide and particulates is interpreted as a synergistic effect; in the author's opinion, this is an aggravating effect. The type of interaction depends on the levels of concentration observed, for example, the synergism shown at high levels of concentration is not always demonstrated for low levels of concentration. In fact there is little evidence of synergistic effects from ambient air pollutant; the more common type of interaction is additive in effect. 12 references.

Computational study of packing a collagen-like molecule: quasi-hexagonal vs "Smith" collagen microfibril model.

Science.gov (United States)

Lee, J; Scheraga, H A; Rackovsky, S

1996-01-01

The lateral packing of a collagen-like molecule, CH3CO-(Gly-L-Pro-L-Pro)4-NHCH3, has been examined by energy minimization with the ECEPP/3 force field. Two current packing models, the Smith collagen microfibril twisted equilateral pentagonal model and the quasi-hexagonal packing model, have been extensively investigated. In treating the Smith microfibril model, energy minimization was carried out on various conformations including those with the symmetry of equivalent packing, i.e., in which the triple helices were arranged equivalently with respect to each other. Both models are based on the experimental observation of the characteristic axial periodicity, D = 67 nm, of light and dark bands, indicating that, if any superstructure exists, it should consist of five triple helices. The quasi-hexagonal packing structure is found to be energetically more favorable than the Smith microfibril model by as much as 31.2 kcal/mol of five triple helices. This is because the quasi-hexagonal packing geometry provides more nonbonded interaction possibilities between triple helices than does the Smith microfibril geometry. Our results are consistent with recent x-ray studies with synthetic collagen-like molecules and rat tail tendon, in which the data were interpreted as being consistent with either a quasi-hexagonal or a square-triangular structure.

Stepwise high-throughput virtual screening of Rho kinase inhibitors from natural product library and potential therapeutics for pulmonary hypertension.

Science.gov (United States)

Su, Hao; Yan, Ji; Xu, Jian; Fan, Xi-Zhen; Sun, Xian-Lin; Chen, Kang-Yu

2015-08-01

Pulmonary hypertension (PH) is a devastating disease characterized by progressive elevation of pulmonary arterial pressure and vascular resistance due to pulmonary vasoconstriction and vessel remodeling. The activation of RhoA/Rho-kinase (ROCK) pathway plays a central role in the pathologic progression of PH and thus the Rho kinase, an essential effector of the ROCK pathway, is considered as a potential therapeutic target to attenuate PH. In the current study, a synthetic pipeline is used to discover new potent Rho inhibitors from various natural products. In the pipeline, the stepwise high-throughput virtual screening, quantitative structure-activity relationship (QSAR)-based rescoring, and kinase assay were integrated. The screening was performed against a structurally diverse, drug-like natural product library, from which six identified compounds were tested to determine their inhibitory potencies agonist Rho by using a standard kinase assay protocol. With this scheme, we successfully identified two potent Rho inhibitors, namely phloretin and baicalein, with activity values of IC50 = 0.22 and 0.95 μM, respectively. Structural examination suggested that complicated networks of non-bonded interactions such as hydrogen bonding, hydrophobic forces, and van der Waals contacts across the complex interfaces of Rho kinase are formed with the screened compounds.

Elementary particle interactions

International Nuclear Information System (INIS)

Bugg, W.M.; Condo, G.T.; Handler, T.; Hart, E.L.; Ward, B.F.L.; Close, F.E.; Christophorou, L.G.

1990-10-01

This report discusses freon bubble chamber experiments exposed to μ + and neutrinos, photon-proton interactions; shower counter simulations; SLD detectors at the Stanford Linear Collider, and the detectors at the Superconducting Super Collider; elementary particle interactions; physical properties of dielectric materials used in High Energy Physics detectors; and Nuclear Physics

Storyboarding Multimedia Interactions.

Science.gov (United States)

Martin, Linda C.

2000-01-01

Understanding how to include interactivity when designing multimedia-based training (MBT) storyboards is a major key for a successful MBT. Discusses the basic formats of interactions and when to use each format. Describes how to storyboard and areas to address, including: the display area, prompts, branching, programming and graphics notes,…

Direct Determination of Chitosan–Mucin Interactions Using a Single-Molecule Strategy: Comparison to Alginate–Mucin Interactions

Directory of Open Access Journals (Sweden)

Kristin E. Haugstad

2015-01-01

Full Text Available Aqueous chitosan possesses attractive interaction capacities with various molecular groups that can be involved in hydrogen bonds and electrostatic and hydrophobic interactions. In the present paper, we report on the direct determination of chitosan–mucin molecular pair interactions at various solvent conditions as compared to alginate–mucin interactions. Two chitosans of high molecular weight with different degrees of acetylation—thus possessing different solubility profiles in aqueous solution as a function of pH and two alginates with different fractions of α-guluronic acid were employed. The interaction properties were determined through a direct unbinding assay at the single-molecular pair level using an atomic force microscope. When probed against immobilized mucin, both chitosans and alginates revealed unbinding profiles characteristic of localized interactions along the polymers. The interaction capacities and estimated parameters of the energy landscapes of the pairwise chitosan–mucin and alginate–mucin interactions are discussed in view of possible contributions from various fundamental forces. Signatures arising both from an electrostatic mechanism and hydrophobic interaction are identified in the chitosan–mucin interaction properties. The molecular nature of the observed chitosan–mucin and alginate–mucin interactions indicates that force spectroscopy provides fundamental insights that can be useful in understanding the surface binding properties of other potentially mucoadhesive polymers.

The lesson learnt during interact - I and INTERACT - II actris measurement campaigns

Directory of Open Access Journals (Sweden)

Rosoldi Marco

2018-01-01

Full Text Available The INTERACT-II (INTERcomparison of Aerosol and Cloud Tracking campaign, performed at the CNR-IMAA Atmospheric Observatory (760 m a.s.l., 40.60° N, 15.72° E, aims to evaluate the performances of commercial automatic lidars and ceilometers for atmospheric aerosol profiling, through the comparison with Potenza EARLINET (European Aerosol Research Lidar NETwork lidars. The results of the campaign and the overall lesson learnt within INTERACT-I and INTERACT-II ACTRIS campaigns will be presented.

B97-3c: A revised low-cost variant of the B97-D density functional method

Science.gov (United States)

Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas; Grimme, Stefan

2018-02-01

A revised version of the well-established B97-D density functional approximation with general applicability for chemical properties of large systems is proposed. Like B97-D, it is based on Becke's power-series ansatz from 1997 and is explicitly parametrized by including the standard D3 semi-classical dispersion correction. The orbitals are expanded in a modified valence triple-zeta Gaussian basis set, which is available for all elements up to Rn. Remaining basis set errors are mostly absorbed in the modified B97 parametrization, while an established atom-pairwise short-range potential is applied to correct for the systematically too long bonds of main group elements which are typical for most semi-local density functionals. The new composite scheme (termed B97-3c) completes the hierarchy of "low-cost" electronic structure methods, which are all mainly free of basis set superposition error and account for most interactions in a physically sound and asymptotically correct manner. B97-3c yields excellent molecular and condensed phase geometries, similar to most hybrid functionals evaluated in a larger basis set expansion. Results on the comprehensive GMTKN55 energy database demonstrate its good performance for main group thermochemistry, kinetics, and non-covalent interactions, when compared to functionals of the same class. This also transfers to metal-organic reactions, which is a major area of applicability for semi-local functionals. B97-3c can be routinely applied to hundreds of atoms on a single processor and we suggest it as a robust computational tool, in particular, for more strongly correlated systems where our previously published "3c" schemes might be problematic.

Soft matter interactions at the molecular scale: interaction forces and energies between single hydrophobic model peptides.

Science.gov (United States)

Stock, Philipp; Utzig, Thomas; Valtiner, Markus

2017-02-08

In all realms of soft matter research a fundamental understanding of the structure/property relationships based on molecular interactions is crucial for developing a framework for the targeted design of soft materials. However, a molecular picture is often difficult to ascertain and yet essential for understanding the many different competing interactions at play, including entropies and cooperativities, hydration effects, and the enormous design space of soft matter. Here, we characterized for the first time the interaction between single hydrophobic molecules quantitatively using atomic force microscopy, and demonstrated that single molecular hydrophobic interaction free energies are dominated by the area of the smallest interacting hydrophobe. The interaction free energy amounts to 3-4 kT per hydrophobic unit. Also, we find that the transition state of the hydrophobic interactions is located at 3 Å with respect to the ground state, based on Bell-Evans theory. Our results provide a new path for understanding the nature of hydrophobic interactions at the single molecular scale. Our approach enables us to systematically vary hydrophobic and any other interaction type by utilizing peptide chemistry providing a strategic advancement to unravel molecular surface and soft matter interactions at the single molecular scale.

Spaces of interaction, places for experience

CERN Document Server

Benyon, David

2014-01-01

Spaces of Interaction, Places for Experience is a book about Human-Computer Interaction (HCI), interaction design (ID) and user experience (UX) in the age of ubiquitous computing. The book explores interaction and experience through the different spaces that contribute to interaction until it arrives at an understanding of the rich and complex places for experience that will be the focus of the next period for interaction design. The book begins by looking at the multilayered nature of interaction and UX-not just with new technologies, but with technologies that are embedded in the world. Peop

Calculations on Noncovalent Interactions and Databases of Benchmark Interaction Energies

Czech Academy of Sciences Publication Activity Database

Hobza, Pavel

2012-01-01

Roč. 45, č. 4 (2012), s. 663-672 ISSN 0001-4842 R&D Projects: GA ČR GBP208/12/G016 Grant - others:European Social Fund(XE) CZ.1.05/2.1.00/03.0058 Institutional research plan: CEZ:AV0Z40550506 Keywords : non-covalent interactions * covalent interactions * quantum chemical approach Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 20.833, year: 2012

Secondary interactions in HIJET

International Nuclear Information System (INIS)

Longacre, R.S.

1990-01-01

This talk deals with the investigation of secondary interactions in proton-nucleus and nucleus-nucleus collisions using the Monte Carlo event generator HIJET. The HIJET generator considers p-A and A-A collisions to be a sum of independent N-N collisions, with the N-N cross section and scattering dynamics not dependent on whether the nucleon has previously participated in an interaction. It is very reasonable to assume that each collision should be well represented by an independent N-N collision, however the cross section for the forward going struck nucleon may be different. For each primary N-N interaction, a call is made to the MINBIAS routine of the program ISAJET - an event generator for high energy N-N interactions. MINBIAS computes the energy loss of the colliding nucleons and production of particles. MINBIAS is based on inclusive high energy N-N interactions forming multi-pomeron chains, with each chain fragmenting according to the Field-Feynman algorithm

Electromagnetic processes and interactions

International Nuclear Information System (INIS)

Scheck, F.

1983-01-01

The electron and muon are important tools in testing the structure of the fundamental electromagnetic interactions. On the other hand, if these interactions are known, they serve as ideal probes for the internal structure of complex hadronic targets such as nucleons and nuclei. Purely electromagnetic interactions play a distinctive role, for obvious experimental reasons: At low and intermediate energies the effective electromagnetic coupling is larger by many orders of magnitude than the weak couplings, so that electromagnetic processes are measurable to much higher accuracy than purely weak processes. The present chapter deals primarily with applications of charged leptons to problems of nucleon and nuclear structure, and to selected precision tests of quantum electrodynamics (QED) at low momentum transfers. In most of these applications the electromagnetic interactions effectively appear in the form of external fields in the leptonic particle's Dirac equation. This is the domain where the physics of (electromagnetically) interacting leptons can still be described in the framework of an effective, though relativistic, single particle theory. (orig.)

Electron propagator calculations on the ionization energies of CrH -, MnH - and FeH -

Science.gov (United States)

Lin, Jyh-Shing; Ortiz, J. V.

1990-08-01

Electron propagator calculations with unrestricted Hartree-Fock reference states yield the ionization energies of the title anions. Spin contamination in the anionic reference state is small, enabling the use of second-and third-order self-energies in the Dyson equation. Feynman-Dyson amplitudes for these ionizations are essentially identical to canonical spin-orbitals. For most of the final states, these consist of an antibonding combination of an sp metal hybrid, polarized away from the hydrogen, and hydroegen s functions. In one case, the Feynman-Dyson amplitude consists of nonbonding d functions. Calculated ionization energies are within 0.5 eV of experiment.

Progress in vacuum metal extraction, refining and consolidation

International Nuclear Information System (INIS)

Sundaram, C.V.; Mukherjee, T.K.; Sharma, B.P.

1973-01-01

The unique achievements in the process metallurgy of rare metals in the past quarter century should largely be attributed to advances in vacuum technology. New standards for high purity, increasing demand for pure metals and alloys for established applications, and steady improvement in sophistication and capacity of vacuum furnaces have provided the stimulus for developing and expanding vacuum metal extraction processes, and also exploring totally new processes. The paper discusses the thermochemistry of vacuum metallurgy, carbothermic and metallothermic reduction reactions, consolidation and refining by vacuum arc melting, electron beam melting and high temperature high vacuum sintering, and ultrapurification, with special reference to the reactive and refractory metals of Group IV to VI. (author)

Procedures for processing power using agricultural waste to Brazil; Processos de transformacao em energia eletrica utilizando residuos agricolas para o Brasil

Energy Technology Data Exchange (ETDEWEB)

Silva, Marcelo Jose da; Souza, Samuel Nelson Melegari de; Santos, Reginaldo Ferreira; Wolff, Paulo Sergio [Universidade do Oeste Paulista (CCET/UNIOESTE), Cascavel, PR (Brazil)], E-mail: ssouza@unioeste.br

2009-07-01

The suitable process for waste vegetable processing is the thermochemistry because of the low moisture promotes the convert ion process. The use of gasified gas generated by an agricultural waste can reduce the consumption of diesel by up to 80% in internal combustion engines. Cogeneration is suitable for the use of crop residues of sugar cane by the mills, generating heat, mechanical and electrical energy. The use of agricultural waste to energy end is an interesting alternative, since it does not compete with food production. Based on calculations for the processing of the cane remains in electric power it was estimated that the generation is 2301.3 million GJ/year by cogeneration. (author)

Interaction in Balanced Cross Nested Designs

Science.gov (United States)

Ramos, Paulo; Mexia, João T.; Carvalho, Francisco; Covas, Ricardo

2011-09-01

Commutative Jordan Algebras, CJA, are used in the study of mixed models obtained, through crossing and nesting, from simpler ones. In the study of cross nested models the interaction between nested factors have been systematically discarded. However this can constitutes an artificial simplification of the models. We point out that, when two crossed factors interact, such interaction is symmetric, both factors playing in it equivalent roles, while when two nested factors interact, the interaction is determined by the nesting factor. These interactions will be called interactions with nesting. In this work we present a coherent formulation of the algebraic structure of models enabling the choice of families of interactions between cross and nested factors using binary operations on CJA.

DIMA 3.0: Domain Interaction Map.

Science.gov (United States)

Luo, Qibin; Pagel, Philipp; Vilne, Baiba; Frishman, Dmitrij

2011-01-01

Domain Interaction MAp (DIMA, available at http://webclu.bio.wzw.tum.de/dima) is a database of predicted and known interactions between protein domains. It integrates 5807 structurally known interactions imported from the iPfam and 3did databases and 46,900 domain interactions predicted by four computational methods: domain phylogenetic profiling, domain pair exclusion algorithm correlated mutations and domain interaction prediction in a discriminative way. Additionally predictions are filtered to exclude those domain pairs that are reported as non-interacting by the Negatome database. The DIMA Web site allows to calculate domain interaction networks either for a domain of interest or for entire organisms, and to explore them interactively using the Flash-based Cytoscape Web software.

Dark patterns in proxemic interactions

DEFF Research Database (Denmark)

Greenberg, Saul; Boring, Sebastian; Vermeulen, Jo

2014-01-01

to better facilitate seamless and natural interactions. To do so, both people and devices are tracked to determine their spatial relationships. While interest in proxemic interactions has increased over the last few years, it also has a dark side: knowledge of proxemics may (and likely will) be easily...... exploited to the detriment of the user. In this paper, we offer a critical perspective on proxemic interactions in the form of dark patterns: ways proxemic interactions can be misused. We discuss a series of these patterns and describe how they apply to these types of interactions. In addition, we identify...

Probing kink interactions with fermions

International Nuclear Information System (INIS)

Carlitz, R.; Chakrabarti, R.

1985-01-01

A dilute gas of kinks exhibits strong but short-ranged intrinsic interactions. When these intrinsic interactions are supplemented by other ''extrinsic'' interactions, a phase transition can occur in which kinks and antikinks bind to form a gas of bounces. The extrinsic interactions arise from the coupling of kinks to an additional degree of freedom, which we take to be a fermion field. The class of quantum-mechanical models which we study includes examples of supersymmetry. The way in which kinks and antikinks bind depends in detail on aspects of the intrinsic interactions. This structure is probably shared by field-theoretic models

Macrolide drug interactions: an update.

Science.gov (United States)

Pai, M P; Graci, D M; Amsden, G W

2000-04-01

To describe the current drug interaction profiles for the commonly used macrolides in the US and Europe, and to comment on the clinical impact of these interactions. A MEDLINE search (1975-1998) was performed to identify all pertinent studies, review articles, and case reports. When appropriate information was not available in the literature, data were obtained from the product manufacturers. All available data were reviewed to provide an unbiased account of possible drug interactions. Data for some of the interactions were not available from the literature, but were available from abstracts or company-supplied materials. Although the data were not always explicit, the best attempt was made to deliver pertinent information that clinical practitioners would need to formulate practice opinions. When more in-depth information was supplied in the form of a review or study report, a thorough explanation of pertinent methodology was supplied. Several clinically significant drug interactions have been identified since the approval of erythromycin. These interactions usually were related to the inhibition of the cytochrome P450 enzyme systems, which are responsible for the metabolism of many drugs. The decreased metabolism by the macrolides has in some instances resulted in potentially severe adverse events. The development and marketing of newer macrolides are hoped to improve the drug interaction profile associated with this class. However, this has produced variable success. Some of the newer macrolides demonstrated an interaction profile similar to that of erythromycin; others have improved profiles. The most success in avoiding drug interactions related to the inhibition of cytochrome P450 has been through the development of the azalide subclass, of which azithromycin is the first and only to be marketed. Azithromycin has not been demonstrated to inhibit the cytochrome P450 system in studies using a human liver microsome model, and to date has produced none of the

Thermo-chemistry of nuclear waste glasses: a new approach; Thermochimie des verres de stockage de dechets nucleaires: une nouvelle approche

Energy Technology Data Exchange (ETDEWEB)

Linard, Y.; Neuville, D.R.; Richet, P. [Institut de Physique du Globe, Lab. de Physique des Geomateriaux, URA CNRS 734, 75 - Paris (France)

1997-07-01

Understanding of the stability and weathering of glasses used for storing fission products is hampered by a general lack of basic thermochemical information. Models have been setup to predict Gibbs free energies of dissolution of glasses, but ascertaining their accuracy is made difficult by the very lack of reliable experimental data with which model results should be compared. As enthalpies of formation can in principle be determined from usual solution calorimetry experiments, the lack of Gibbs-free energy data for glasses mainly stems from the fact that, as disordered substances, glasses do not obey the third principle and have indeed large configurational entropies. These entropies can be determined from thermochemical measurements only when there exist a congruently melting crystalline compound with the same composition. Using available data, we have calculated the Gibbs-free energies of formation of a series of silicate glasses for which such a calorimetric determination is possible. With these results, we assess the predictions of Paul's model (1977) for calculating Gibbs-free energies of dissolution. As the complex compositions of the borosilicate glasses used for nuclear waste storage prevent determining configurational entropies by calorimetric methods, we point out how these can be determined instead from viscosity measurements. We finally discuss the implications of this approach for modeling of water-glass interactions. (authors)

Computations and interaction

NARCIS (Netherlands)

Baeten, J.C.M.; Luttik, S.P.; Tilburg, van P.J.A.; Natarajan, R.; Ojo, A.

2011-01-01

We enhance the notion of a computation of the classical theory of computing with the notion of interaction. In this way, we enhance a Turing machine as a model of computation to a Reactive Turing Machine that is an abstract model of a computer as it is used nowadays, always interacting with the user

Programming Interactivity

CERN Document Server

Noble, Joshua

2009-01-01

Make cool stuff. If you're a designer or artist without a lot of programming experience, this book will teach you to work with 2D and 3D graphics, sound, physical interaction, and electronic circuitry to create all sorts of interesting and compelling experiences -- online and off. Programming Interactivity explains programming and electrical engineering basics, and introduces three freely available tools created specifically for artists and designers: Processing, a Java-based programming language and environment for building projects on the desktop, Web, or mobile phonesArduino, a system t

Tritium-surface interactions

International Nuclear Information System (INIS)

Kirkaldy, J.S.

1983-06-01

The report deals broadly with tritium-surface interactions as they relate to a fusion power reactor enterprise, viz., the vacuum chamber, first wall, peripherals, pumping, fuel recycling, isotope separation, repair and maintenance, decontamination and safety. The main emphasis is on plasma-surface interactions and the selection of materials for fusion chamber duty. A comprehensive review of the international (particularly U.S.) research and development is presented based upon a literature review (about 1 000 reports and papers) and upon visits to key laboratories, Sandia, Albuquerque, Sandia, Livermore and EGβG Idaho. An inventory of Canadian expertise and facilities for RβD on tritium-surface interactions is also presented. A number of proposals are made for the direction of an optimal Canadian RβD program, emphasizing the importance of building on strength in both the technological and fundamental areas. A compendium of specific projects and project areas is presented dealing primarily with plasma-wall interactions and permeation, anti-permeation materials and surfaces and health, safety and environmental considerations. Potential areas of industrial spinoff are identified

Duplicability of self-interacting human genes.

LENUS (Irish Health Repository)

Pérez-Bercoff, Asa

2010-01-01

BACKGROUND: There is increasing interest in the evolution of protein-protein interactions because this should ultimately be informative of the patterns of evolution of new protein functions within the cell. One model proposes that the evolution of new protein-protein interactions and protein complexes proceeds through the duplication of self-interacting genes. This model is supported by data from yeast. We examined the relationship between gene duplication and self-interaction in the human genome. RESULTS: We investigated the patterns of self-interaction and duplication among 34808 interactions encoded by 8881 human genes, and show that self-interacting proteins are encoded by genes with higher duplicability than genes whose proteins lack this type of interaction. We show that this result is robust against the system used to define duplicate genes. Finally we compared the presence of self-interactions amongst proteins whose genes have duplicated either through whole-genome duplication (WGD) or small-scale duplication (SSD), and show that the former tend to have more interactions in general. After controlling for age differences between the two sets of duplicates this result can be explained by the time since the gene duplication. CONCLUSIONS: Genes encoding self-interacting proteins tend to have higher duplicability than proteins lacking self-interactions. Moreover these duplicate genes have more often arisen through whole-genome rather than small-scale duplication. Finally, self-interacting WGD genes tend to have more interaction partners in general in the PIN, which can be explained by their overall greater age. This work adds to our growing knowledge of the importance of contextual factors in gene duplicability.

Green synthesis and characterization of cuprous oxide nanoparticles in presence of a bio-surfactant

Science.gov (United States)

Behera, M.; Giri, G.

2014-12-01

Herein, we report a facile green synthesis of Cu2O nanoparticles (NPs) using copper sulfate as precursor salt and hydrazine hydrate as reducing agent in presence of bio-surfactant (i.e. leaves extract of arka — a perennial shrub) at 60 to 70 °C in an aqueous medium. A broad band centered at 460 nm in absorption spectrum reveals the formation of surfactant stabilized Cu2O NPs. X-ray diffraction pattern of the surfactant stabilized NPs suggests the formation of only Cu2O phase in assistance of a bio-surfactant with the crystallite size of ˜8 nm. A negative zeta potential of -12 mV at 8.0 pH in surfactant stabilized Cu2O NPs hints non-bonding electron transfer from O-atom of saponin to the surface of NP. Red-shift in the vibrational band (Cu-O stretching) of Cu2O from 637 cm-1 to 640 cm-1 in presence of bio-surfactant suggests an interfacial interaction between NPs and O-atoms of -OH groups of saponin present in the plant (i.e. Calotropis gigantean) extract. From X-ray photoelectron spectroscopy spectra, a decrease in binding energy of both 2p3/2 and 2p1/2 bands in Cu2O with saponin molecules as compared to bulk Cu atom reveals a charge transfer interaction between NP and saponin surfactant molecules. Transmission electron microscopy images show crystalline nature of Cu2O NPs with an fcc lattice.

Crystallization in melts of short, semiflexible hard polymer chains: An interplay of entropies and dimensions

Science.gov (United States)

Shakirov, T.; Paul, W.

2018-04-01

What is the thermodynamic driving force for the crystallization of melts of semiflexible polymers? We try to answer this question by employing stochastic approximation Monte Carlo simulations to obtain the complete thermodynamic equilibrium information for a melt of short, semiflexible polymer chains with purely repulsive nonbonded interactions. The thermodynamics is obtained based on the density of states of our coarse-grained model, which varies by up to 5600 orders of magnitude. We show that our polymer melt undergoes a first-order crystallization transition upon increasing the chain stiffness at fixed density. This crystallization can be understood by the interplay of the maximization of different entropy contributions in different spatial dimensions. At sufficient stiffness and density, the three-dimensional orientational interactions drive the orientational ordering transition, which is accompanied by a two-dimensional translational ordering transition in the plane perpendicular to the chains resulting in a hexagonal crystal structure. While the three-dimensional ordering can be understood in terms of Onsager theory, the two-dimensional transition can be understood in terms of the liquid-hexatic transition of hard disks. Due to the domination of lateral two-dimensional translational entropy over the one-dimensional translational entropy connected with columnar displacements, the chains form a lamellar phase. Based on this physical understanding, orientational ordering and translational ordering should be separable for polymer melts. A phenomenological theory based on this understanding predicts a qualitative phase diagram as a function of volume fraction and stiffness in good agreement with results from the literature.

pH and temperature effects on the molecular conformation of the porcine pancreatic secretory trypsin inhibitor as detected by hydrogen-1 nuclear magnetic resonance

International Nuclear Information System (INIS)

De Marco, A.; Menegatti, E.; Guarneri, M.

1982-01-01

1 H NMR spectra of the porcine pancreatic secretory trypsin inhibitor (PSTI) have been recorded vs. pH and temperature. Of the two tyrosines, one titrates with a pK of 1.25, while the resonances from the other are pH insensitive in the investigated range 4.8 less than or equal to pH less than or equal to 12. This is consistent with PSTI having one Tyr solvent exposed (Try-20) and the other buried (Tyr-31). The resonances from the lysyl epsilon-CH 2 protons titrate with a pK of 10.95. The titration is accompanied by a pronounced line broadening, which starts near pH 8.5. Between pH 11.5 and pH 12 the epsilon-CH 2 resonances recover their low pH line width. Titration curves for the lysines and Tyr-20 reflect single proton ionization equilibria, suggesting that these residues do not interact among themselves. On the basis of double resonance experiments, combined with analysis of chemical shifts, spin-spin couplngs, and line widths, all methyl resonances are identified and followed as functions of pH and temperature. The γ-CH 3 doublet from the N-terminal Thr-1 is assigned by comparison between spectra of forms I and II of the inhibitor, the latter lacking the first four residues of form I. The β-CH 3 resonance from Ala-7 is also assigned. Proton resonance parameters of methyl groups are shown to afford useful NMR probes for the characterization of local nonbonded interactions, microenvironments, and mobilities

Computational insight into small molecule inhibition of cyclophilins.

Science.gov (United States)

Sambasivarao, Somisetti V; Acevedo, Orlando

2011-02-28

Cyclophilins (Cyp) are a family of cellular enzymes possessing peptidyl-prolyl isomerase activity, which catalyze the cis-trans interconversion of proline-containing peptide bonds. The two most abundant family members, CypA and CypB, have been identified as valid drug targets for a wide range of diseases, including HCV, HIV, and multiple cancers. However, the development of small molecule inhibitors that possess nM potency and high specificity for a particular Cyp is difficult given the complete conservation of all active site residues between the enzymes. Monte Carlo statistical sampling coupled to free energy perturbation theory (MC/FEP) calculations have been carried out to elucidate the origin of the experimentally observed nM inhibition of CypA by acylurea-based derivatives and the >200-fold in vitro selectivity between CypA and CypB from aryl 1-indanylketone-based μM inhibitors. The computed free-energies of binding were in close accord with those derived from experiments. Binding affinity values for the inhibitors were determined to be dependent upon the stabilization strength of the nonbonded interactions provided toward two catalytic residues: Arg55 and Asn102 in CypA and the analogous Arg63 and Asn110 residues in CypB. Fine-tuning of the hydrophobic interactions allowed for enhanced potency among derivatives. The aryl 1-indanylketones are predicted to differentiate between the cyclophilins by using distinct binding motifs that exploit subtle differences in the active site arrangements. Ideas for the development of new selective compounds with the potential for advancement to low-nanomolar inhibition are presented.

Mechanical and geometric controls on the structural evolution of pit crater and caldera subsidence

Science.gov (United States)

Holohan, E. P.; SchöPfer, M. P. J.; Walsh, J. J.

2011-07-01

Pit craters and calderas are volcanic depressions produced by subsidence of a magma reservoir roof. To identify how geometric and mechanical factors may influence the structural evolution of this subsidence, we used two-dimensional distinct element method numerical models. The reservoir host rock was represented as an assemblage of bonded circular particles that interact according to elastic-frictional laws. Varying particle and bond properties produced a range of bulk material properties characteristic of natural rock masses. Fracturing results when bonds break, once their shear or tensile strength is exceeded. The magma reservoir was represented as a region of nonbonded low-friction particles. Withdrawal of magma was simulated by incrementally reducing the area of the reservoir particles. Resultant gravity-driven failure and subsidence of the reservoir roof were explicitly replicated. Interaction of the roof's strength, Young's modulus, thickness/diameter ratio (T/D), and the reservoir's shape yields a variety of model structures and subsidence styles. In conceptual terms, four end-member subsidence styles developed: (1) "central sagging" favored by low strength and low T/D; (2) "central snapping" favored by high strength, low T/D, and a sill-like reservoir shape; (3) "single central block" favored by low to intermediate strength, high Young's modulus, and intermediate T/D; and (4) "multiple central blocks" favored by high strength, low Young's modulus, and high T/D. Most model realizations incorporated some combination of each style, however. The models provide a geomechanical framework for understanding natural pit crater or caldera structures, as at Nindiri (Nicaragua), Fernandina (Galapagos), Dolomieu (La Reunion), and Miyakejima (Japan).

Image Representation and Interactivity: An Exploration of Utility Values, Information-Needs and Image Interactivity

Science.gov (United States)

Lewis, Elise C.

2011-01-01

This study was designed to explore the relationships between users and interactive images. Three factors were identified and provided different perspectives on how users interact with images: image utility, information-need, and images with varying levels of interactivity. The study used a mixed methodology to gain a more comprehensive…

Non-equilibrium fluctuation-induced interactions

International Nuclear Information System (INIS)

Dean, David S

2012-01-01

We discuss non-equilibrium aspects of fluctuation-induced interactions. While the equilibrium behavior of such interactions has been extensively studied and is relatively well understood, the study of these interactions out of equilibrium is relatively new. We discuss recent results on the non-equilibrium behavior of systems whose dynamics is of the dissipative stochastic type and identify a number of outstanding problems concerning non-equilibrium fluctuation-induced interactions.

A conserved mammalian protein interaction network.

Directory of Open Access Journals (Sweden)

Åsa Pérez-Bercoff

Full Text Available Physical interactions between proteins mediate a variety of biological functions, including signal transduction, physical structuring of the cell and regulation. While extensive catalogs of such interactions are known from model organisms, their evolutionary histories are difficult to study given the lack of interaction data from phylogenetic outgroups. Using phylogenomic approaches, we infer a upper bound on the time of origin for a large set of human protein-protein interactions, showing that most such interactions appear relatively ancient, dating no later than the radiation of placental mammals. By analyzing paired alignments of orthologous and putatively interacting protein-coding genes from eight mammals, we find evidence for weak but significant co-evolution, as measured by relative selective constraint, between pairs of genes with interacting proteins. However, we find no strong evidence for shared instances of directional selection within an interacting pair. Finally, we use a network approach to show that the distribution of selective constraint across the protein interaction network is non-random, with a clear tendency for interacting proteins to share similar selective constraints. Collectively, the results suggest that, on the whole, protein interactions in mammals are under selective constraint, presumably due to their functional roles.

Experimental study on the thermochemistry of some amino derivatives of uracil

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Amaral, Luisa M.P.F.; Szterner, Piotr

2011-01-01

Highlights: → Combustion calorimetry was used to determine Δ f H m 0 (cr) of amino derivatives of uracil. → Gas-phase Δ f H m 0 of amino derivatives of uracil have been derived. → The relative enthalpic stability of the title compounds is discussed in structural terms. - Abstract: Values of the standard (p 0 = 0.1 MPa) molar enthalpy of combustion, Δ c H m 0 , of four crystalline compounds: 5-aminouracil, 6-aminouracil, 6-amino-1-methyluracil, and 6-amino-1,3-dimethyluracil, were determined, at T = 298.15 K, using a static bomb combustion calorimeter. The values obtained of standard molar enthalpy of combustion were used to derive the standard molar enthalpy of formation of the compounds investigated in their condensed phase and together with literature values of the standard molar enthalpy of sublimation, yielded the standard molar enthalpies of formation in the gaseous phase. These are discussed in terms of the effects of the molecular structure on the relative enthalpic stability.

Experimental study on the thermochemistry of 5-nitroindole and 5-nitroindoline

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.

2009-01-01

The standard (p0 = 0.1 MPa) molar enthalpies of combustion of 5-nitroindole and 5-nitroindoline, both in the solid phase, were measured at T = 298.15 K by static bomb calorimetry. Further, the standard molar enthalpies of sublimation, at T = 298.15 K, of these two indole derivatives were determined by Knudsen effusion technique. The combustion calorimetry results together with those from the Knudsen effusion technique, were used to derive the standard molar enthalpies of formation, at T = 298.15 K, in the gaseous phase. Values are presented in a table

Thermochemistry of the complex oxides of uranium, vanadium, and alkali metals

International Nuclear Information System (INIS)

Karyakin, N.V.; Chernorukov, N.G.; Suleimanov, E.V.; Kharyushina, E.A.

1992-01-01

The standard enthalpies of the formation at T 298.15 K of complex oxides of uranium(VI), vanadium(V) and alkali metals with the general formula M 1 VUO 6 where M 1 = Na, K, Rb, and Cs, were calculated from the results of calorimetric experiments and from published data. 8 refs., 1 tab

An Investigation of the Crystalchemistry and Thermochemistry of Selected Mineral Systems.

Science.gov (United States)

1987-10-29

PURPOSES AD-A 189 7581OCUMENTATION PAGE Is. REPOW Mb. RESTRICTIVE MARINGS iJf FL ui 3.DITRIDUTION /AVAILABIUTY OF REPOR 2b. DECLASSIFICATIONIOOWNGRAOiNG...Continuous Observation of Phase Transformations ", Journal of Metals Abstract April 1986. 5. Reeber, R.R. and Tesche, B. (1987) "Synchrotron...RD-AIlS ?59 AN INYESTIGATION OF THE CRYSTALCHENISTRY AND THERMNOCENISTRY OF SELECTED..(U) NORTH CAROLINA UNIV AT CHAPEL HILL DEPT OF GEOLOGY R R

Thermochemistry of adducts of some bivalent transition metal bromides with aniline

International Nuclear Information System (INIS)

Dunstan, Pedro Oliver

2006-01-01

The compounds [MBr 2 (an) 2 ] (where M is Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II); an=aniline) were synthesized and characterized by melting points, elemental analysis, thermal studies, and electronic and IR spectroscopy. The enthalpies of dissolution of the adducts, metal(II) bromides and aniline in methanol, aqueous 1.2M HCl or 25% (v/v) aqueous 1.2M HCl in methanol were measured. The following thermochemical parameters for the adducts have been determined by thermochemical cycles: the standard enthalpies for the Lewis acid/base reactions (Δ r H o ), the standard enthalpies of formation (Δ f H o ), the standard enthalpies of decomposition (Δ D H o ), the lattice standard enthalpies (Δ M H o ) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (Δ r H o (g)). The mean bond dissociation enthalpies of the M(II)-nitrogen bonds (D-bar (M?N) ) and the enthalpies of formation of the adducts from the ions in the gaseous phase: M 2+ (g) +Br - (g) +an (g) ->[MBr 2 (an) 2 ] (g) (Δ fi H o ) have been estimated

Pyrite thermochemistry, ash agglomeration, and char fragmentation during pulverized coal combustion

Energy Technology Data Exchange (ETDEWEB)

Akan-Etuk, A.; Diaz, R.; Niksa, S.

1991-10-01

The objective of the present work is to introduce an experimental program that will eventually lead to time-resolved iron ash composition over the technological operating domain. The preceding literature survey suggests two important stipulations on any such experimental program. The first stipulation is that good control must be established over the operating conditions, to accurately quantify their effects. The other is that data must be obtained rapidly, to thoroughly cover the important operating domain. This work presents a series of studies that has characterized the desulfurization of pyrite during the early stages of combustion. An experimental system was established and used to monitor the effects of oxygen, temperature, and residence time on the evolution of condensed phase products of the combustion of pure pyrite. (VC)

Interaction of Myosin Phosphatase Target Subunit (MYPT1) with Myosin Phosphatase-RhoA Interacting Protein (MRIP): A Role of Glutamic Acids in the Interaction.

Science.gov (United States)

Lee, Eunhee; Stafford, Walter F

2015-01-01

Scaffold proteins bind to and functionally link protein members of signaling pathways. Interaction of the scaffold proteins, myosin phosphatase target subunit (MYPT1) and myosin phosphatase-RhoA interacting protein (MRIP), causes co-localization of myosin phosphatase and RhoA to actomyosin. To examine biophysical properties of interaction of MYPT1 with MRIP, we employed analytical ultracentrifugation and surface plasmon resonance. In regard to MRIP, its residues 724-837 are sufficient for the MYPT1/MRIP interaction. Moreover, MRIP binds to MYPT1 as either a monomer or a dimer. With respect to MYPT1, its leucine repeat region, LR (residues 991-1030) is sufficient to account for the MYPT1/MRIP interaction. Furthermore, point mutations that replace glutamic acids 998-1000 within LR reduced the binding affinity toward MRIP. This suggests that the glutamic acids of MYPT1 play an important role in the interaction.

Antiproton-nucleus interaction

International Nuclear Information System (INIS)

Gibbs, W.R.

1984-01-01

Several facets of antinucleon-nucleus interactions are explored. The topics treated are: coherent interactions, production of unusual states and particles in the nuclear medium, and the creation of extreme states of matter by antimatter annihilation. It is found that temperatures of the magnitude necessary to achieve the predicted quark-gluon phase transition are obtained. 20 references

Expanding the Interaction Equivalency Theorem

Directory of Open Access Journals (Sweden)

Brenda Cecilia Padilla Rodriguez

2015-06-01

Full Text Available Although interaction is recognised as a key element for learning, its incorporation in online courses can be challenging. The interaction equivalency theorem provides guidelines: Meaningful learning can be supported as long as one of three types of interactions (learner-content, learner-teacher and learner-learner is present at a high level. This study sought to apply this theorem to the corporate sector, and to expand it to include other indicators of course effectiveness: satisfaction, knowledge transfer, business results and return on expectations. A large Mexican organisation participated in this research, with 146 learners, 30 teachers and 3 academic assistants. Three versions of an online course were designed, each emphasising a different type of interaction. Data were collected through surveys, exams, observations, activity logs, think aloud protocols and sales records. All course versions yielded high levels of effectiveness, in terms of satisfaction, learning and return on expectations. Yet, course design did not dictate the types of interactions in which students engaged within the courses. Findings suggest that the interaction equivalency theorem can be reformulated as follows: In corporate settings, an online course can be effective in terms of satisfaction, learning, knowledge transfer, business results and return on expectations, as long as (a at least one of three types of interaction (learner-content, learner-teacher or learner-learner features prominently in the design of the course, and (b course delivery is consistent with the chosen type of interaction. Focusing on only one type of interaction carries a high risk of confusion, disengagement or missed learning opportunities, which can be managed by incorporating other forms of interactions.

"Help Me Pull That Cursor" A Collaborative Interactive Floor Enhancing Community Interaction

Directory of Open Access Journals (Sweden)

Peter Krogh

2004-05-01

Full Text Available In this paper we describe the development, experiments and evaluation of the iFloor, an interactive floor prototype installed at the local central municipality library. The primary purpose of the iFloor prototype is to support and stimulate community interaction between collocated people. The context of the library demands that any user can walk up and use the prototype without any devices or prior introduction. To achieve this, the iFloor proposes innovative interaction (modes/paradigms/patterns for floor surfaces through the means of video tracking. Browsing and selecting content is done in a collaborative process and mobile phones are used for posting messages onto the floor. The iFloor highlights topics on social issues of ubiquitous computing environments in public spaces, and provides an example of how to exploit human spatial movements, positions and arrangements in interaction with computers.

Interactive Learning in SME-University Collaborations: A Conceptual Framework for Facilitating Interaction

DEFF Research Database (Denmark)

Filip, Diane

2013-01-01

. The facilitation process focuses on interactive learning and is divided into phases, which makes it easier for SMEs to progressive engage in innovation projects with researchers. In-depth interviews with the facilitators of the programme were conducted and focused on barriers to collaboration, human interaction......, and lessons learned. From the facilitators’ perspective, a conceptual model capturing the main actor’s activities in each phase paralleled with an illustration of the narrowed gap from the human interaction is presented in the paper. The main findings addressed the issues of human-based and system......-based barriers. One of the lessons learned is the importance of human interaction of narrowing the perceived gap by mitigating the human-based barriers, and to some extent also system-based barriers. The case presented in this paper has managerial and innovation policy implications....

Making an Interactive Calculus Textbook.

Science.gov (United States)

Larson, Timothy R.

1995-01-01

Presents a case study of the design and production of "Interactive Calculus," an interactive multimedia textbook. Discusses reasons for using multimedia textbooks; what an interactive textbook is; content, organization, graphic design, authoring and composition; and work flow. (AEF)

Interactive Dimensioning of Parametric Models

KAUST Repository

Kelly, T.

2015-06-22

We propose a solution for the dimensioning of parametric and procedural models. Dimensioning has long been a staple of technical drawings, and we present the first solution for interactive dimensioning: A dimension line positioning system that adapts to the view direction, given behavioral properties. After proposing a set of design principles for interactive dimensioning, we describe our solution consisting of the following major components. First, we describe how an author can specify the desired interactive behavior of a dimension line. Second, we propose a novel algorithm to place dimension lines at interactive speeds. Third, we introduce multiple extensions, including chained dimension lines, controls for different parameter types (e.g. discrete choices, angles), and the use of dimension lines for interactive editing. Our results show the use of dimension lines in an interactive parametric modeling environment for architectural, botanical, and mechanical models.

Trivalent metallocene chemistry of some uranium, titanium, and zirconium complexes

International Nuclear Information System (INIS)

Lukens, W.W. Jr.

1995-05-01

Dicyclopentadienyluranium halide dimers have been prepared and their solution behavior examined. These molecules exist as dimers in solution, and the halide ligands undergo rapid site exchange on the NMR timescale above 50 C. Analogous dicyclopentadienyluranium hydroxide dimers have also been prepared; they oxidatively eliminate hydrogen to give the corresponding oxide dimers. Mechanism of this reaction is consistent with αmigration of one of the hydroxide hydrogen atoms to a uranium center followed by elimination of hydrogen. Ground state of [(Me 3 Si) 2 C 5 H 3 ] 3 M M = Nd, U and their base adducts has been examined by variable temperature magnetic susceptibility and EPR spectroscopy. The ground state is found to be 4 I 9/2 with a crystal field state consisting largely of J z = 1/2 lowest, in agreement with previous studies on tris-cyclopentadienylneodymium complexes. The zirconium metallocene Cp 3 Zr has been prepared, characterized crystallographically, and its reactivity studied. Its chemical behavior is controlled by presence of an electron in the non-bonding, d z 2 orbital which prevents formation of base adducts Of Cp 3 Zr, but allows Cp 3 Zr to abstract atoms from other molecules. Electonic and EPR spectra of Cp* 2 TiX complexes, where Cp* is Me 5 C 5 and X is a monodentate, anionic ligand such as halide, have been studied. A π-bonding spectrochemical series is developed, and trends in π-bonding ability are found similar to those in other inorganic complexes. The β-agostic interactions in Cp* 2 TiN(Me)Ph have been examined using variable temperature EPR spectroscopy, and the enthalpy/entropy of the interaction determined. In Cp* 2 TiEt, enthalpy of the β-agostic interaction is -1.9 kcal/mol. The titanocene anion, Cp* 2 TiLi(TMEDA) (TMEDA is N,N,N',N'-tetramethylethylenediamine), has been prepared and its structure determined

Scoring predictive models using a reduced representation of proteins: model and energy definition.

Science.gov (United States)

Fogolari, Federico; Pieri, Lidia; Dovier, Agostino; Bortolussi, Luca; Giugliarelli, Gilberto; Corazza, Alessandra; Esposito, Gennaro; Viglino, Paolo

2007-03-23

Reduced representations of proteins have been playing a keyrole in the study of protein folding. Many such models are available, with different representation detail. Although the usefulness of many such models for structural bioinformatics applications has been demonstrated in recent years, there are few intermediate resolution models endowed with an energy model capable, for instance, of detecting native or native-like structures among decoy sets. The aim of the present work is to provide a discrete empirical potential for a reduced protein model termed here PC2CA, because it employs a PseudoCovalent structure with only 2 Centers of interactions per Amino acid, suitable for protein model quality assessment. All protein structures in the set top500H have been converted in reduced form. The distribution of pseudobonds, pseudoangle, pseudodihedrals and distances between centers of interactions have been converted into potentials of mean force. A suitable reference distribution has been defined for non-bonded interactions which takes into account excluded volume effects and protein finite size. The correlation between adjacent main chain pseudodihedrals has been converted in an additional energetic term which is able to account for cooperative effects in secondary structure elements. Local energy surface exploration is performed in order to increase the robustness of the energy function. The model and the energy definition proposed have been tested on all the multiple decoys' sets in the Decoys'R'us database. The energetic model is able to recognize, for almost all sets, native-like structures (RMSD less than 2.0 A). These results and those obtained in the blind CASP7 quality assessment experiment suggest that the model compares well with scoring potentials with finer granularity and could be useful for fast exploration of conformational space. Parameters are available at the url: http://www.dstb.uniud.it/~ffogolari/download/.

Interactive lectures in engineering education

NARCIS (Netherlands)

van Dijk, L.A.; van den Berg, G.C.; van Keulen, H.

2001-01-01

This article discusses an alternative approach to lecturing: the interactive lecture. In the literature, interactive teaching is forwarded as a means to increase the effectiveness of lectures. Members of lecturing staff still seem, however, reluctant to incorporate interactive teaching in their

SNP interaction pattern identifier (SIPI)

DEFF Research Database (Denmark)

Lin, Hui Yi; Chen, Dung Tsa; Huang, Po Yu

2017-01-01

Motivation: Testing SNP-SNP interactions is considered as a key for overcoming bottlenecks of genetic association studies. However, related statistical methods for testing SNP-SNP interactions are underdeveloped. Results: We propose the SNP Interaction Pattern Identifier (SIPI), which tests 45...

Our interests in protein-protein interactions

Indian Academy of Sciences (India)

protein interactions. Evolution of P-P partnerships. Evolution of P-P structures. Evolutionary dynamics of P-P interactions. Dynamics of P-P interaction network. Host-pathogen interactions. CryoEM mapping of gigantic protein assemblies.

Exploring sonic interaction design and presence: Natural Interactive Walking in Porto

DEFF Research Database (Denmark)

Nordahl, Rolf; Serafin, Stefania; Fontana, Frederico

2009-01-01

In this paper we report on the results of a three days workshop whose goal was to combine interactive sounds and soundscape design to simulate the sensation of walking in a specific location of Porto. We discuss advantages and disadvantages of the different solutions proposed in terms of the tech......In this paper we report on the results of a three days workshop whose goal was to combine interactive sounds and soundscape design to simulate the sensation of walking in a specific location of Porto. We discuss advantages and disadvantages of the different solutions proposed in terms...... of the technology used, and issues of how sonic interaction combined with soundscape design affects presence in virtual environments....

Health Data Interactive (HDI)

Data.gov (United States)

U.S. Department of Health & Human Services — Health Data Interactive (HDI) presents a broad range of important public health indicators through an interactive web-based application that provides access to...

Introduction to a Protein Interaction System Used for Quantitative Evaluation of Biomolecular Interactions

OpenAIRE

Yamniuk, Aaron

2013-01-01

A central goal of molecular biology is the determination of biomolecular function. This comes largely from a knowledge of the non-covalent interactions that biological small and macro-molecules experience. The fundamental mission of the Molecular Interactions Research Group (MIRG) of the ABRF is to show how solution biophysical tools are used to quantitatively characterize molecular interactions, and to educate the ABRF members and scientific community on the utility and limitations of core t...

Online Learners' Preferences for Interaction.

Science.gov (United States)

Northrup, Pamela T.

2002-01-01

Describes a study that investigated types of interaction that graduate students perceived to be important for elearning (electronic learning). Discusses content interaction, conversation and collaboration, interpersonal and metacognitive skills, and need for support; explains the Online Learning Interaction Inventory; and reports that flexibility…

Strongly interacting Fermi gases

Directory of Open Access Journals (Sweden)

Bakr W.

2013-08-01

Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.

Parent-child interactions during traditional and interactive media settings: A pilot randomized control study.

Science.gov (United States)

Skaug, Silje; Englund, Kjellrun T; Saksvik-Lehouillier, Ingvild; Lydersen, Stian; Wichstrøm, Lars

2018-04-01

Parent-child interactions are pivotal for children's socioemotional development, yet might suffer with increased attention to screen media, as research has suggested. In response, we hypothesized that parent-child play on a tablet computer, as representative of interactive media, would generate higher-quality parent-child interactions than toy play or watching TV. We examined the emotional availability of mothers and their 2-year-old child during the previous three contexts using a randomized crossover design (n = 22) in a laboratory room. Among other results, mothers were more sensitive and structuring during joint gaming on a tablet than when engaged in toy play or watching TV. In addition, mothers were more hostile toward their children during play with traditional toys than during joint tablet gaming and television co-viewing. Such findings provide new insights into the impact of new media on parent-child interactions, chiefly by demonstrating that interactive media devices such as tablets can afford growth-enhancing parent-child interactions. © 2017 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Novicidin interactions with phospholipid membranes

DEFF Research Database (Denmark)

Balakrishnan, Vijay Shankar

Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting with lipos......Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting...... with liposomes. The lipid-induced changes in the peptide due to membrane binding, and the peptide-induced changes in the membrane properties were investigated using various spectroscopic and calorimetric methods, and the structural and thermodynamic aspects of peptide-lipid interactions are discussed. This helps...

Quark confinement and hadronic interactions

International Nuclear Information System (INIS)

Lenz, F.

1985-01-01

With the possibility for 'exact' calculations within the framework of a fundamental theory, QCD, the role of models in strong interaction physics is changing radically. The relevance of detailed numerical model studies is diminishing with the development of those exact, numerical approaches to QCD. On the other hand, the insight gained from such purely numerical studies is necessarily limited and must be complemented by the more qualitative but also more intuitive insight gained from model studies. In particular, the subject of hadron-hadron interactions requires model studies to relate the wide variety of strong interaction physics to the fundamental properties of strong interaction physics. The author reports on such model studies of the hadron-hadron interaction