Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures

International Nuclear Information System (INIS)

Jozefowicz, Marek; Heldt, Janina R.

2003-01-01

Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures has been studied using steady-state spectroscopic measurements. This study concerns the solvent-induced shift of the absorption and fluorescence spectra of both molecules in two solvent mixtures, i.e., cyclohexane-tetrahydrofuran and cyclohexane-ethanol. The first system contains polar solute molecules, fluorenone and 4-hydroxyfluorenone, in a mixture of polar aprotic (tetrahydrofuran) and non-polar (cyclohexane) solvents. In the second solvents mixture, hydrogen bonding with solute molecules (ethanol) may occur. The results of spectroscopic measurements are analysed using theoretical models of Bakshiev, Mazurenko and Suppan which describe preferential solvation phenomena. In the case of cyclohexane-tetrahydrofuran mixtures, the deviation from linearity in the absorption and fluorescence solvatochromic shifts vs. the solution polarity is due to non-specific dipolar solvent-solute interactions. For cyclohexane-ethanol binary mixtures, both non-specific and specific (hydrogen bond and proton-relay tautomerization) interactions contribute to the observed solvatochromism

Symmetry Adaptation of the Rotation-Vibration Theory for Linear Molecules

Directory of Open Access Journals (Sweden)

Katy L. Chubb

2018-04-01

Full Text Available A numerical application of linear-molecule symmetry properties, described by the D ∞ h point group, is formulated in terms of lower-order symmetry groups D n h with finite n. Character tables and irreducible representation transformation matrices are presented for D n h groups with arbitrary n-values. These groups can subsequently be used in the construction of symmetry-adapted ro-vibrational basis functions for solving the Schrödinger equations of linear molecules. Their implementation into the symmetrisation procedure based on a set of “reduced” vibrational eigenvalue problems with simplified Hamiltonians is used as a practical example. It is shown how the solutions of these eigenvalue problems can also be extended to include the classification of basis-set functions using ℓ, the eigenvalue (in units of ℏ of the vibrational angular momentum operator L ^ z . This facilitates the symmetry adaptation of the basis set functions in terms of the irreducible representations of D n h . 12 C 2 H 2 is used as an example of a linear molecule of D ∞ h point group symmetry to illustrate the symmetrisation procedure of the variational nuclear motion program Theoretical ROVibrational Energies (TROVE.

Chiral domain formation from the mixture of achiral rod-like liquid crystal and tri boomerang-shaped molecule

Science.gov (United States)

Lee, Ji-Hoon; Yoon, Tae-Hoon

2013-08-01

Spontaneous formation of chiral domains such as a helical filament and a bent-broom texture was observed from the mixture of a rod-like liquid crystal octylcyano-biphenyl (8CB) and a tri boomerang-shaped 2,4,6-triphenoxy-1,3,5-triazine (triphenoxy) molecule. Although the constituent molecules were achiral, their mixture showed the chiral domains with the equal fraction of the opposite handedness. No tilt of 8CB molecules in the smectic layer was observed, implying the chirality is not due to the polar packing and tilt of the molecules. In addition, the splay and bend elastic constant of 8CB was decreased after doping triphenoxy. A structural conformation of triphenoxy and an orientational coupling between 8CB and triphenoxy are considered to be related to the chiral domain formation.

The interaction of linear and ring forms of DNA molecules with nanodiamonds synthesized by detonation

International Nuclear Information System (INIS)

Purtov, K V; Burakova, L P; Puzyr, A P; Bondar, V S

2008-01-01

Nanodiamonds synthesized by detonation have been found not to immobilize the ring form of pUC19 plasmid DNA. Linear pUC19 molecules with blunt ends, prepared by restriction of the initial ring form of pUC19 DNA, and linear 0.25-10 kb DNA fragments are adsorbed on nanodiamonds. The amount of adsorbed linear DNA molecules depends on the size of the molecules and the size of the nanodiamond clusters

Quantum Phases of Atom-Molecule Mixtures of Fermionic Atoms

Science.gov (United States)

Lopez, Nicolas; Tsai, Shan-Wen

2009-11-01

Cold atom experiments have observed atom-molecule mixtures by tuning the interactions between particles.footnotetextM.L. Olsen, J. D. Perreault, T. D. Cumby, and D. S. Jin, Phys. Rev. A 80, 030701(R) (2009) We study many particle interactions by examaning a simple model that describes the destruction of fermionic atom pairs to form single bosonic molecules and vice versa. A set of functional Renomalization Group equationsfootnotetextR. Shankar, Rev. Mod. Phys., Vol 66 No. 1, January 1994^,footnotetextS.W. Tsai, A.H. Castro Neto, R. Shankar, D.K. Campbell, Phys. Rev. B 72, 054531 (2005) describing these processes are set up and solved numerically. The Self Energy of the fermions are attained as a function of frequency and we search for frequency dependent instabilities that could denote a transition from a disordered liquid to a BCS phase. (Financial support from NSF DMR-084781 and UC-Lab Fees Research Program.)

Superradiance Effects in the Linear and Nonlinear Optical Response of Quantum Dot Molecules

Science.gov (United States)

Sitek, A.; Machnikowski, P.

2008-11-01

We calculate the linear optical response from a single quantum dot molecule and the nonlinear, four-wave-mixing response from an inhomogeneously broadened ensemble of such molecules. We show that both optical signals are affected by the coupling-dependent superradiance effect and by optical interference between the two polarizations. As a result, the linear and nonlinear responses are not identical.

Ion-molecule reactions in the binary mixture of ethylene oxide and trioxane, 2

International Nuclear Information System (INIS)

Kumakura, Minoru; Arakawa, Kazuo; Sugiura, Toshio.

1978-01-01

The ion-molecule reactions in the binary mixture of ethylene oxide and trioxane have been studied with use of a modified time-of-flight mass spectrometer. As cross-reaction product ions, C 3 H 5 O 2 + , C 3 H 6 O 2 +sup(, and C**3**H**7**O**2**)+sup( were observed under the conditions of long delay times and elevated pressure. It was found that these ions are formed by the dissociation of unstable intermediate-complex resulting from the reaction of ethylene oxide molecular ion with trioxane. It was proposed that the complex is of cyclic structure in which positive charge is delocalized. From the consideration of isotopic distribution of the product ions in ethylene-d**4** oxide-trioxane mixtures, the skeletal structures of the product ions were investigated. The rate constants of the formation reactions of C**3**H**5**O**2**)+sup(, C**3**H**6**O**2**)+sup(, and C**3**H**7**O**2**)+sup( in ethylene oxide-trioxane mixtures were found to be 2.20 x 10)-10sup(, 2.61 x 10)-10sup(, and 1.74 x 10)-10sup( cm)3sup( molecule)-1sup(s)-1 , respectively. (auth.)

Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic molecules

DEFF Research Database (Denmark)

Williams, J. E.; Nygaard, Nicolai; Clark, C. W.

2004-01-01

We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use of a tunable Feshbach resonance. We plot...... diagrams obtained in recent experiments on the Bose-Einstein condensation to Bardeen-Cooper-Schrieffer crossover, in which the condensate fraction is plotted as a function of the initial temperature of the Fermi gas measured before a sweep of the magnetic field through the resonance region....

A reciprocal theorem for a mixture theory. [development of linearized theory of interacting media

Science.gov (United States)

Martin, C. J.; Lee, Y. M.

1972-01-01

A dynamic reciprocal theorem for a linearized theory of interacting media is developed. The constituents of the mixture are a linear elastic solid and a linearly viscous fluid. In addition to Steel's field equations, boundary conditions and inequalities on the material constants that have been shown by Atkin, Chadwick and Steel to be sufficient to guarantee uniqueness of solution to initial-boundary value problems are used. The elements of the theory are given and two different boundary value problems are considered. The reciprocal theorem is derived with the aid of the Laplace transform and the divergence theorem and this section is concluded with a discussion of the special cases which arise when one of the constituents of the mixture is absent.

Electron re-scattering from aligned linear molecules using the R-matrix method

International Nuclear Information System (INIS)

Harvey, A G; Tennyson, J

2009-01-01

Electron re-scattering in a strong laser field provides an important probe of molecular structure and processes. The laser field drives the ionization of the molecule, followed by acceleration and subsequent recollision of the electron with the parent molecular ion, the scattered electrons carry information about the nuclear geometry and electronic states of the molecular ion. It is advantageous in strong field experiments to work with aligned molecules, which introduces extra physics compared to the standard gas-phase, electron-molecule scattering problem. The formalism for scattering from oriented linear molecules is presented and applied to H 2 and CO 2 . Differential cross sections are presented for (re-)scattering by these systems concentrating on the most common, linear alignment. In H 2 these cross sections show significant angular structure which, particularly for a scattering angle of 90 deg., are predicted to vary significantly between re-collisions stimulated by an even or an odd number of photons. In CO 2 these cross sections are zero indicating the necessity of using non-parallel alignment with this molecule.

Linear kinetic theory and particle transport in stochastic mixtures

International Nuclear Information System (INIS)

Pomraning, G.C.

1994-03-01

The primary goal in this research is to develop a comprehensive theory of linear transport/kinetic theory in a stochastic mixture of solids and immiscible fluids. The statistics considered correspond to N-state discrete random variables for the interaction coefficients and sources, with N denoting the number of components of the mixture. The mixing statistics studied are Markovian as well as more general statistics, such as renewal processes. A further goal of this work is to demonstrate the applicability of the formalism to real world engineering problems. This three year program was initiated June 15, 1993 and has been underway nine months. Many significant results have been obtained, both in the formalism development and in representative applications. These results are summarized by listing the archival publications resulting from this grant, including the abstracts taken directly from the papers

Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe - CsCl mixture

Science.gov (United States)

Boichenko, A. M.; Klenovskii, M. S.

2015-12-01

By using the previously developed kinetic model, we have carried out simulations to study the possibility of laser generation of XeCl exciplex molecules in the working medium based on a mixture of Xe with CsCl vapours, excited by a longitudinal repetitively pulsed discharge. The formation mechanism of exciplex molecules in this mixture is fundamentally different from the formation mechanisms in the traditional mixtures of exciplex lasers. The conditions that make the laser generation possible are discussed. For these conditions, with allowance for available specific experimental conditions of the repetitively pulsed discharge excitation, we have obtained the calculated dependences of the power and efficiency of generation on the reflectivity of mirrors in a laser cavity.

Mixtures of ultracold atoms and the quest for ultracold molecules

International Nuclear Information System (INIS)

Weidemueller, M.

2000-08-01

A cold atomic gas formed by two different species represents an intriguing system for a deeper understanding of atom-atom interactions at ultralow temperatures. We present experiments on a mixture of atomic lithium and cesium which are of particular interest regarding the formation of heteronuclear molecules on the one hand, and the prospects for sympathetic cooling of atomic gases through mutual thermalization on the other hand. A first series of experiments on interaction in presence of a near-resonant light field is performed in a two-species magneto-optical trap. The collisional properties of the lithium-cesium mixture are investigated through detailed analysis of trap-loss processes induced by the trap light. Photoassociation in an additional near-resonant laser field yields high-resolution spectra of the excited Cs 2 dimers, but shows no unambiguous indication of LiCs molecule formation. A second series of experiments on pure ground-state collisional properties utilizes an optical dipole trap formed by light that is detuned extremely far below atomic resonance (quasi-electrostatic trap). Storage times of many minutes are achieved in a particularly simple and versatile setup for both atomic species. Cooling of cesium through evaporation and thermalization by elastic collisions is observed. The evolution of temperature and particle number is compared with model simulations of evaporative cooling. Direct laser cooling of trapped cesium in the absolute energetic ground state is demonstrated. Homonuclear spin-changing collisions of ground-state cesium and lithium atoms are analyzed, and first evidence for pure ground-state collisions between atoms of different species is found. Based on the current achievements, prospects for future experiments are discussed. (orig.)

Linear-algebraic approach to electron-molecule collisions: General formulation

International Nuclear Information System (INIS)

Collins, L.A.; Schneider, B.I.

1981-01-01

We present a linear-algebraic approach to electron-molecule collisions based on an integral equations form with either logarithmic or asymptotic boundary conditions. The introduction of exchange effects does not alter the basic form or order of the linear-algebraic equations for a local potential. In addition to the standard procedure of directly evaluating the exchange integrals by numerical quadrature, we also incorporate exchange effects through a separable-potential approximation. Efficient schemes are developed for reducing the number of points and channels that must be included. The method is applied at the static-exchange level to a number of molecular systems including H 2 , N 2 , LiH, and CO 2

Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe – CsCl mixture

International Nuclear Information System (INIS)

Boichenko, A M; Klenovskii, M S

2015-01-01

By using the previously developed kinetic model, we have carried out simulations to study the possibility of laser generation of XeCl exciplex molecules in the working medium based on a mixture of Xe with CsCl vapours, excited by a longitudinal repetitively pulsed discharge. The formation mechanism of exciplex molecules in this mixture is fundamentally different from the formation mechanisms in the traditional mixtures of exciplex lasers. The conditions that make the laser generation possible are discussed. For these conditions, with allowance for available specific experimental conditions of the repetitively pulsed discharge excitation, we have obtained the calculated dependences of the power and efficiency of generation on the reflectivity of mirrors in a laser cavity. (active media)

Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe – CsCl mixture

Energy Technology Data Exchange (ETDEWEB)

Boichenko, A M [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Klenovskii, M S [National Research Tomsk Polytechnic University, Tomsk (Russian Federation)

2015-12-31

By using the previously developed kinetic model, we have carried out simulations to study the possibility of laser generation of XeCl exciplex molecules in the working medium based on a mixture of Xe with CsCl vapours, excited by a longitudinal repetitively pulsed discharge. The formation mechanism of exciplex molecules in this mixture is fundamentally different from the formation mechanisms in the traditional mixtures of exciplex lasers. The conditions that make the laser generation possible are discussed. For these conditions, with allowance for available specific experimental conditions of the repetitively pulsed discharge excitation, we have obtained the calculated dependences of the power and efficiency of generation on the reflectivity of mirrors in a laser cavity. (active media)

Importance of the alignment of polar π conjugated molecules inside carbon nanotubes in determining second-order non-linear optical properties.

Science.gov (United States)

Yumura, Takashi; Yamamoto, Wataru

2017-09-20

We employed density functional theory (DFT) calculations with dispersion corrections to investigate energetically preferred alignments of certain p,p'-dimethylaminonitrostilbene (DANS) molecules inside an armchair (m,m) carbon nanotube (n × DANS@(m,m)), where the number of inner molecules (n) is no greater than 3. Here, three types of alignments of DANS are considered: a linear alignment in a parallel fashion and stacking alignments in parallel and antiparallel fashions. According to DFT calculations, a threshold tube diameter for containing DANS molecules in linear or stacking alignments was found to be approximately 1.0 nm. Nanotubes with diameters smaller than 1.0 nm result in the selective formation of linearly aligned DANS molecules due to strong confinement effects within the nanotubes. By contrast, larger diameter nanotubes allow DANS molecules to align in a stacking and linear fashion. The type of alignment adopted by the DANS molecules inside a nanotube is responsible for their second-order non-linear optical properties represented by their static hyperpolarizability (β 0 values). In fact, we computed β 0 values of DANS assemblies taken from optimized n × DANS@(m,m) structures, and their values were compared with those of a single DANS molecule. DFT calculations showed that β 0 values of DANS molecules depend on their alignment, which decrease in the following order: linear alignment > parallel stacking alignment > antiparallel stacking alignment. In particular, a linear alignment has a β 0 value more significant than that of the same number of isolated molecules. Therefore, the linear alignment of DANS molecules, which is only allowed inside smaller diameter nanotubes, can strongly enhance their second-order non-linear optical properties. Since the nanotube confinement determines the alignment of DANS molecules, a restricted nanospace can be utilized to control their second-order non-linear optical properties. These DFT findings can assist in the

Spinodal decomposition in a food colloid-biopolymer mixture: evidence for a linear regime

Energy Technology Data Exchange (ETDEWEB)

Bhat, Suresh [Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, 1700 Fribourg (Switzerland); Tuinier, Remco [Forschungszentrum Juelich, Institut fuer Festkoerperforschung, 52425 Juelich (Germany); Schurtenberger, Peter [Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, 1700 Fribourg (Switzerland)

2006-07-05

We investigate phase separation and structural evolution in a complex food colloid (casein micelles) and biopolymer (xanthan) mixture using small-angle light scattering. We demonstrate that phase separation is induced by a depletion mechanism, and that the resulting coexistence curve can be described by osmotic equilibrium theory for mixtures of colloids and polymer chains in a background solvent, taking into account interactions between the polymer chains in the excluded volume limit. We show that the light scattering pattern of an unstable mixture exhibits the typical behaviour of spinodal decomposition, and we are able to confirm the validity of dynamic similarity scaling. We find three distinct regimes (initial or linear, intermediate and transition stage) for the decomposition kinetics that differ in the time dependence of the peak position of the structure factor. In particular we find clear evidence for the existence of an initial linear regime, where the peak position remains constant and the amplitude grows. The existence of spinodal-like decomposition and the validity of universal scaling in the intermediate and transition stages have been found in previous studies of phase separation in attractive colloidal suspensions. However, to our knowledge the initial linear regime has never been observed in colloidal suspensions, and we attribute this at least partly to the effect of hydrodynamic interactions which are efficiently screened in our system due to the fact that the measurements were performed at high polymer concentrations, i.e. in the semi-dilute regime. (letter to the editor)

Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

KAUST Repository

Yoo, Hyejin

2012-10-25

Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

KAUST Repository

Yoo, Hyejin; Furumaki, Shu; Yang, Jaesung; Lee, Ji-Eun; Chung, Heejae; Oba, Tatsuya; Kobayashi, Hiroyuki; Rybtchinski, Boris; Wilson, Thea M.; Wasielewski, Michael R.; Vacha, Martin; Kim, Dongho

2012-01-01

Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

Application of the method of continued fractions for electron scattering by linear molecules

International Nuclear Information System (INIS)

Lee, M.-T.; Iga, I.; Fujimoto, M.M.; Lara, O.; Brasilia Univ., DF

1995-01-01

The method of continued fractions (MCF) of Horacek and Sasakawa is adapted for the first time to study low-energy electron scattering by linear molecules. Particularly, we have calculated the reactance K-matrices for an electron scattered by hydrogen molecule and hydrogen molecular ion as well as by a polar LiH molecule in the static-exchange level. For all the applications studied herein. the calculated physical quantities converge rapidly, even for a strongly polar molecule such as LiH, to the correct values and in most cases the convergence is monotonic. Our study suggests that the MCF could be an efficient method for studying electron-molecule scattering and also photoionization of molecules. (Author)

Rotational partition functions for linear molecules

International Nuclear Information System (INIS)

McDowell, R.S.

1988-01-01

An accurate closed-form expression for the rotational partition function of linear polyatomic molecules in 1 summation electronic states is derived, including the effect of nuclear spin (significant at very low temperatures) and of quartic and sextic centrifugal distortion terms (significant at moderate and high temperatures). The proper first-order quantum correction to the classical rigid-rotator partition function is shown to yield Q/sub r/ ≅β -1 exp(β/3), where βequivalenthcB/kT and B is the rotational constant in cm -1 ; for β≥0.2 additional power-series terms in β are necessary. Comparison between the results of this treatment and exact summations are made for HCN and C 2 H 2 at temperatures from 2 to 5000 K, including separate evaluation of the contributions of nuclear spin and centrifugal distortion

Study on infrared multiphoton excitation of the linear triatomic molecule by the Lie-algebra approach

International Nuclear Information System (INIS)

Feng, H.; Zheng, Y.; Ding, S.

2007-01-01

Infrared multiphoton vibrational excitation of the linear triatomic molecule has been studied using the quadratic anharmonic Lie-algebra model, unitary transformations, and Magnus approximation. An explicit Lie-algebra expression for the vibrational transition probability is obtained by using a Lie-algebra approach. This explicit Lie-algebra expressions for time-evolution operator and vibrational transition probabilities make the computation clearer and easier. The infrared multiphoton vibrational excitation of the DCN linear tri-atomic molecule is discussed as an example

Band-selective excited ultrahigh resolution PSYCHE-TOCSY: fast screening of organic molecules and complex mixtures.

Science.gov (United States)

Kakita, Veera Mohana Rao; Vemulapalli, Sahithya Phani Babu; Bharatam, Jagadeesh

2016-04-01

Precise assignments of (1) H atomic sites and establishment of their through-bond COSY or TOCSY connectivity are crucial for molecular structural characterization by using (1) H NMR spectroscopy. However, this exercise is often hampered by signal overlap, primarily because of (1) H-(1) H scalar coupling multiplets, even at typical high magnetic fields. The recent developments in homodecoupling strategies for effectively suppressing the coupling multiplets into nice singlets (pure-shift), particularly, Morris's advanced broadband pure-shift yielded by chirp excitation (PSYCHE) decoupling and ultrahigh resolution PSYCHE-TOCSY schemes, have shown new possibilities for unambiguous structural elucidation of complex organic molecules. The superior broadband PSYCHE-TOCSY exhibits enhanced performance over the earlier TOCSY methods, which however warrants prolonged experimental times due to the requirement of large number of dwell increments along the indirect dimension. Herein, we present fast and band-selective analog of the broadband PSYCHE-TOCSY, which is useful for analyzing complex organic molecules that exhibit characteristic yet crowded spectral regions. The simple pulse scheme relies on band-selective excitation (BSE) followed by PSYCHE homodecoupling in the indirect dimension. The BSE-PSYCHE-TOCSY has been exemplified for Estradiol and a complex carbohydrate mixture comprised of six constituents of closely comparable molecular weights. The experimental times are greatly reduced viz., ~20 fold for Estradiol and ~10 fold for carbohydrate mixture, with respect to the broadband PSYCHE-TOCSY. Furthermore, unlike the earlier homonuclear band-selective decoupling, the BSE-PSYCHE-decoupling provides fully decoupled pure-shift spectra for all the individual chemical sites within the excited band. The BSE-PSYCHE-TOCSY is expected to have significant potential for quick screening of complex organic molecules and mixtures at ultrahigh resolution. Copyright © 2015 John Wiley

Developing Density of Laser-Cooled Neutral Atoms and Molecules in a Linear Magnetic Trap

Science.gov (United States)

Velasquez, Joe, III; Walstrom, Peter; di Rosa, Michael

2013-05-01

In this poster we show that neutral particle injection and accumulation using laser-induced spin flips may be used to form dense ensembles of ultracold magnetic particles, i.e., laser-cooled paramagnetic atoms and molecules. Particles are injected in a field-seeking state, are switched by optical pumping to a field-repelled state, and are stored in the minimum-B trap. The analogous process in high-energy charged-particle accumulator rings is charge-exchange injection using stripper foils. The trap is a linear array of sextupoles capped by solenoids. Particle-tracking calculations and design of our linear accumulator along with related experiments involving 7Li will be presented. We test these concepts first with atoms in preparation for later work with selected molecules. Finally, we present our preliminary results with CaH, our candidate molecule for laser cooling. This project is funded by the LDRD program of Los Alamos National Laboratory.

Ion swarm data for electrical discharge modeling in air and flue gas mixtures

International Nuclear Information System (INIS)

Nelson, D.; Benhenni, M.; Eichwald, O.; Yousfi, M.

2003-01-01

The first step of this work is the determination of the elastic and inelastic ion-molecule collision cross sections for the main ions (N 2 + , O 2 + , CO 2 + , H 2 O + and O - ) usually present either in the air or flue gas discharges. The obtained cross section sets, given for ion kinetic energies not exceeding 100 eV, correspond to the interactions of each ion with its parent molecule (symmetric case) or nonparent molecule (asymmetric case). Then by using these different cross section sets, it is possible to obtain the ion swarm data for the different gas mixtures involving N 2 , CO 2 , H 2 O and O 2 molecules whatever their relative proportions. These ion swarm data are obtained from an optimized Monte Carlo method well adapted for the ion transport in gas mixtures. This also allows us to clearly show that the classical linear approximations usually applied for the ion swarm data in mixtures such as Blanc's law are far to be valid. Then, the ion swarm data are given in three cases of gas mixtures: a dry air (80% N 2 , 20% O 2 ), a ternary gas mixture (82% N 2 , 12% CO 2 , 6% O 2 ) and a typical flue gas (76% N 2 , 12% CO 2 , 6% O 2 , 6% H 2 O). From these reliable ion swarm data, electrical discharge modeling for a wire to plane electrode configuration has been carried out in these three mixtures at the atmospheric pressure for different applied voltages. Under the same discharge conditions, large discrepancies in the streamer formation and propagation have been observed in these three mixture cases. They are due to the deviations existing not only between the different effective electron-molecule ionization rates but also between the ion transport properties mainly because of the presence of a highly polar molecule such as H 2 O. This emphasizes the necessity to properly consider the ion transport in the discharge modeling

Ion-molecule reactions in the binary mixture of ethylene oxide and trioxane, 1

International Nuclear Information System (INIS)

Kumakura, Minoru; Sugiura, Toshio.

1977-01-01

The formation mechanism of protonated molecular ions by cross-reactions in ethylene oxide-trioxane mixtures has been studied with use of a modified time-of-flight mass spectrometer. The precursors of the product ions were determined by analysis of the fine structure of their ionization efficiency curves using deuterated ethylene oxide. Protonated ethylene oxide is formed by the hydrogen atom transfer reaction of ethylene oxide molecular ion with trioxane, and protonated trioxane by the proton transfer reaction of CHO + (from ethylene oxide) with trioxane. In the ion-molecule reactions of ethylene-d 4 oxide-trioxane mixtures, appreciable isotope effect was observed. The CHO + from ethylene oxide is an important reactant ion as compared with that from trioxane in the proton transfer reaction, and CHO + from ethylene oxide was suggested as a thermal reactive ion. The order of proton affinity could be estimated from the proton transfer reactions involving CHO + . It was found that the proton affinity of trioxane is smaller than that of ethylene oxide. (auth.)

Conformational Effects in Non-Stoichiometric Complexes of Two Hyperbranched Molecules with a Linear Polyelectrolyte

Directory of Open Access Journals (Sweden)

Alexey Lyulin

2012-01-01

Full Text Available We report results from Brownian dynamics computer simulations of systems comprised by two terminally charged hyperbranched molecules preferentially branched in the periphery, with an oppositely charged linear chain of varying length. Comparison of the findings from the present study to stoichiometric counterparts and to analogous dendrimer-based complexes, reveal that the presence of the second hyperbranched molecule incurs significant changes in the conformational characteristics of both components of the complex. Instead of step-like changes in the average size and shape of the hyperbranched component that were noted in the previously studied stoichiometric systems, a rather smooth change is observed upon increase of the length of the linear component. In addition, a markedly different behavior is also noticed in the conformational characteristics of the linear chain when compared to that in similar dendrimer-based systems. The above findings are consistent with the higher degree of deformability of the peripherally branched molecules which allow appropriate rearrangements in shape in order to accommodate the favorable Coulombic interactions between the two components of the complex. This behavior offers new insight towards the design of more efficient hyperbranched-based systems which can take advantage of the multifunctionality and the structural properties of the highly branched polymer components.

Phase behavior of diblock copolymer/star-shaped polymer thin film mixtures.

Science.gov (United States)

Zhao, Junnan; Sakellariou, Georgios; Green, Peter F

2016-05-07

We investigated the phase behavior of thin film, thickness h≈ 100 nm, mixtures of a polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer with star-shaped polystyrene (SPS) molecules of varying functionalities f, where 4 ≤f≤ 64, and molecular weights per arm Marm. The miscibility of the system and the surface composition varied appreciably with Marm and f. For large values of Marm, regardless of f, the miscibility of the system was qualitatively similar to that of linear chain PS/PS-b-P2VP mixtures - the copolymer chains aggregate to form micelles, each composed of an inner P2VP core and PS corona, which preferentially segregate to the free surface. On the other hand, for large f and small Marm, SPS molecules preferentially resided at the free surface. Moreover, blends containing SPS molecules with the highest values of f and lowest values of Marm were phase separated. These observations are rationalized in terms of competing entropic interactions and the dependence of the surface tension of the star-shaped molecules on Marm and f.

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

Science.gov (United States)

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

2017-09-20

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

Detection of kinetic change points in piece-wise linear single molecule motion

Science.gov (United States)

Hill, Flynn R.; van Oijen, Antoine M.; Duderstadt, Karl E.

2018-03-01

Single-molecule approaches present a powerful way to obtain detailed kinetic information at the molecular level. However, the identification of small rate changes is often hindered by the considerable noise present in such single-molecule kinetic data. We present a general method to detect such kinetic change points in trajectories of motion of processive single molecules having Gaussian noise, with a minimum number of parameters and without the need of an assumed kinetic model beyond piece-wise linearity of motion. Kinetic change points are detected using a likelihood ratio test in which the probability of no change is compared to the probability of a change occurring, given the experimental noise. A predetermined confidence interval minimizes the occurrence of false detections. Applying the method recursively to all sub-regions of a single molecule trajectory ensures that all kinetic change points are located. The algorithm presented allows rigorous and quantitative determination of kinetic change points in noisy single molecule observations without the need for filtering or binning, which reduce temporal resolution and obscure dynamics. The statistical framework for the approach and implementation details are discussed. The detection power of the algorithm is assessed using simulations with both single kinetic changes and multiple kinetic changes that typically arise in observations of single-molecule DNA-replication reactions. Implementations of the algorithm are provided in ImageJ plugin format written in Java and in the Julia language for numeric computing, with accompanying Jupyter Notebooks to allow reproduction of the analysis presented here.

Brome isotope selective control of CF3Br molecule clustering by IR laser radiation in gas-dynamic expansion of CF3Br - Ar mixture

Science.gov (United States)

Apatin, V. M.; Lokhman, V. N.; Makarov, G. N.; Ogurok, N.-D. D.; Ryabov, E. A.

2018-02-01

We report the results of research on the experimental control of CF3Br molecule clustering under gas-dynamic expansion of the CF3Br - Ar mixture at a nozzle exit by using IR laser radiation. A cw CO2 laser is used for exciting molecules and clusters in the beam and a time-of-flight mass-spectrometer with laser UV ionisation of particles for their detection. The parameters of the gas above the nozzle are determined (compositions and pressure) at which intensive molecule clustering occurs. It is found that in the case of the CF3Br gas without carrier when the pressure P0 above the nozzle does not exceed 4 atm, molecular clusters actually are not generated in the beam. If the gas mixture of CF3Br with argon is used at a pressure ratio 1 : N, where N >= 3, and the total pressure above the nozzle is P0 >= 2 atm, then there occurs molecule clustering. We study the dependences of the efficiency of suppressing the molecule clustering on parameters of the exciting pulse, gas parameters above the nozzle, and on a distance of the molecule irradiation zone from the nozzle exit section. It is shown that in the case of resonant vibrational excitation of gas-dynamically cooled CF3Br molecules at the nozzle exit one can realise isotope-selective suppression of molecule clustering with respect to bromine isotopes. With the CF3Br - Ar mixtures having the pressure ratio 1 : 3 and 1 : 15, the enrichment factors obtained with respect to bromine isotopes are kenr ≈ 1.05 ± 0.005 and kenr ≈ 1.06 ± 0.007, respectively, under jet irradiation by laser emission in the 9R(30) line (1084.635 cm-1). The results obtained let us assume that this method can be used to control clustering of molecules comprising heavy element isotopes, which have a small isotopic shift in IR absorption spectra.

Polarization properties of below-threshold harmonics from aligned molecules H2+ in linearly polarized laser fields.

Science.gov (United States)

Dong, Fulong; Tian, Yiqun; Yu, Shujuan; Wang, Shang; Yang, Shiping; Chen, Yanjun

2015-07-13

We investigate the polarization properties of below-threshold harmonics from aligned molecules in linearly polarized laser fields numerically and analytically. We focus on lower-order harmonics (LOHs). Our simulations show that the ellipticity of below-threshold LOHs depends strongly on the orientation angle and differs significantly for different harmonic orders. Our analysis reveals that this LOH ellipticity is closely associated with resonance effects and the axis symmetry of the molecule. These results shed light on the complex generation mechanism of below-threshold harmonics from aligned molecules.

A quasi-linear formulation for chemically reacting compressible mixtures of imperfect gases

Science.gov (United States)

Lentini, D.

2008-01-01

A quasi-linear formulation is proposed for high-speed finite-rate chemically reacting mixtures of imperfect gases, i.e., thermally perfect gases with specific heat varying with temperature. It retains the same formalism of a well-tried counterpart formulation for perfect gases, which has been proven to be suited for application of accurate and fast algorithms. Equations for both quasi-monodimensional flows, and for axisymmetric viscous flows are presented. The approach is based on the definition of an appropriate function F of temperature and concentration, which allows to identify Riemann variables for the flow under consideration; the formulation also includes equations for the entropy and the mass fractions of the N chemical species present in the reacting mixture. The key function F must be computed by numerical quadrature, together with its derivatives with respect to the individual species mass fractions. An example of computation of these quantities is reported, with reference to conditions in the combustion chamber of the Vulcain engine powering the first stage of the Ariane 5 launcher. Such a computation is demonstrated to be both economic and accurate, thus proving the workability of the proposed approach. Further, an estimate of the variation of the mixture specific heat ratio with temperature is given, in order to underline the importance of the effect under consideration.

Liquids and liquid mixtures

CERN Document Server

Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

2013-01-01

Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

Lanczos-driven coupled-cluster damped linear response theory for molecules in polarizable environments

DEFF Research Database (Denmark)

List, Nanna Holmgaard; Coriani, Sonia; Kongsted, Jacob

2014-01-01

are specifically motivated by a twofold aim: (i) computation of core excitations in realistic surroundings and (ii) examination of the effect of the differential response of the environment upon excitation solely related to the CC multipliers (herein denoted the J matrix) in computations of excitation energies......We present an extension of a previously reported implementation of a Lanczos-driven coupled-cluster (CC) damped linear response approach to molecules in condensed phases, where the effects of a surrounding environment are incorporated by means of the polarizable embedding formalism. We...... and transition moments of polarizable-embedded molecules. Numerical calculations demonstrate that the differential polarization of the environment due to the first-order CC multipliers provides only minor contributions to the solvatochromic shift for all transitions considered. We thus complement previous works...

Thermodynamics of mixtures containing alkoxyethanols. XXVIII: Liquid-liquid equilibria for 2-phenoxyethanol + selected alkanes

Energy Technology Data Exchange (ETDEWEB)

Alonso, Victor; Garcia, Mario [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain); Gonzalez, Juan Antonio, E-mail: jagl@termo.uva.es [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain); Garcia De La Fuente, Isaias; Cobos, Jose Carlos [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain)

2011-07-10

Highlights: {yields} LLE coexistence curves were determined for mixtures of 2PhEE with alkanes. {yields} UCST values are higher for n-alkane systems than for solutions with cyclic alkanes. {yields} For the latter mixtures, UCST increases with the size of the alkyl group attached. {yields} Alkoxyethanol-alkoxyethanol interactions are enhanced by aromatic group in cellosolve. - Abstract: The coexistence curves of the liquid-liquid equilibria (LLE) for systems of 2-phenoxyethanol (2PhEE) with heptane, octane, cyclohexane, methylcyclohexane or ethylcyclohexane have been determined by the method of the critical opalescence using a laser scattering technique. All the curves show an upper critical solution temperature (UCST), have a rather horizontal top and their symmetry depends on the relative size of the mixture compounds. UCST values are higher for systems with linear alkanes than for solutions including cyclic alkanes. For these mixtures, the UCST increases with the size of the alkyl group attached to the cyclic part of the molecule. It is shown that interactions between alkoxyethanol molecules are stronger when the hydroxyether contains an aromatic group. Data are used to determine the critical exponent for the order parameter mole fraction. Values obtained are consistent with those provided by the Ising model or by the renormalization group theory.

Thermodynamics of mixtures containing alkoxyethanols. XXVIII: Liquid-liquid equilibria for 2-phenoxyethanol + selected alkanes

International Nuclear Information System (INIS)

Alonso, Victor; Garcia, Mario; Gonzalez, Juan Antonio; Garcia De La Fuente, Isaias; Cobos, Jose Carlos

2011-01-01

Highlights: → LLE coexistence curves were determined for mixtures of 2PhEE with alkanes. → UCST values are higher for n-alkane systems than for solutions with cyclic alkanes. → For the latter mixtures, UCST increases with the size of the alkyl group attached. → Alkoxyethanol-alkoxyethanol interactions are enhanced by aromatic group in cellosolve. - Abstract: The coexistence curves of the liquid-liquid equilibria (LLE) for systems of 2-phenoxyethanol (2PhEE) with heptane, octane, cyclohexane, methylcyclohexane or ethylcyclohexane have been determined by the method of the critical opalescence using a laser scattering technique. All the curves show an upper critical solution temperature (UCST), have a rather horizontal top and their symmetry depends on the relative size of the mixture compounds. UCST values are higher for systems with linear alkanes than for solutions including cyclic alkanes. For these mixtures, the UCST increases with the size of the alkyl group attached to the cyclic part of the molecule. It is shown that interactions between alkoxyethanol molecules are stronger when the hydroxyether contains an aromatic group. Data are used to determine the critical exponent for the order parameter mole fraction. Values obtained are consistent with those provided by the Ising model or by the renormalization group theory.

On the I-V characteristic in the non-linear tenary mixture model for polycrystalline semiconductors

International Nuclear Information System (INIS)

Nguyen Van Lien; Nguyen Hoai Nam

2000-08-01

A simple expression for the voltage dependence of grain-boundary potential barrier heights is proposed and the Effective Medium Approximation is extended for calculating the I-V characteristic in tenary mixtures of highly non-linear circuit elements. Numerical calculations are performed for the case of polycrystalline semiconductors, such as ZnO-based varistors, where the thermoionic emission is believed to be the dominant mechanism for the electric conduction across double Schottky barriers at room temperature. (author)

studies dielectric behaviour of some long chain alcohols and their mixtures with a non-polar solvent at various concentration

International Nuclear Information System (INIS)

Yaqub, M.; Ahmed, S.S.; Hussain, A.

2006-01-01

Dielectric constant, refractive index and the Kirkwood linear correlation factor of 1-propanol, 1-butanol and 1-pentanol in mixtures with carbon tetrachloride at various concentration have been measured at fixed frequency (100 KHz) at 303.15 K. For the study of dielectric properties of polar molecules in a non-polar solvent at different concentrations, polarization per unit volume and excess free-energy of mixing were evaluated at this temperature. In order to study the association of polar molecules in such a non-polar solvent, the Kirkwood correlation factor (g) between molecular pairs, which exists due to the hydrogen bond association suggesting the presence of some dimension in the liquid phase with a number of dimmers, was determined. The refractive index and dielectric constant measurements are expected to shed some light on the configuration of molecules in various mixtures, and give some idea about the specific interactions between components, which decrese with the increase in the concentration of alcohol. All the three mixtures showed different behaviour for the value of correlation factor (g) as a function of concentration. The response of 1-pentanol was broadly identical to that of small chain alcohols. The different behaviour of the correlation factor (g) was interpreted in terms of the Kirkwood-Frohlich theory, as it takes into account, explicitly, such type of short and long range interactions of a mixture of polar molecules with non-polar solvents. (author)

Molecular-beam electric-resonance studies of linear triatomic molecules

International Nuclear Information System (INIS)

Reinartz, J.M.L.J.

1976-01-01

In the present work, the MBER technique has been employed to investigate the spectra of the high temperature species KCN and CsOH and at low temperatures the spectra of five different isotopic species of OCS in natural mixture and the most abundant isotopic species of N 2 O and ClCN. For the low temperature species, spectra in the ground state and in the first excited state of the bending mode have been obtained. Bending vibrational effects on hyperfine constants and on electric and magnetic constants have been deduced from these spectra. The introduction of nozzle beam sources has been a factor of great importance for this study. For the ground states, high resolution spectra have been obtained both in external electric and in combined parallel electric and magnetic fields. These spectra could well be explained by the known theories for molecules in a 1 Σ state to within an experimental accuracy of about 50-150 Hz. Extension of the theory needed for the interpretation of the spectra for excited bending states is given. Hyperfine properties and electric and magnetic constants have been obtained with very high accuracy from the analysis of the frequencies of the observed transitions within one rotational state (ΔJ = 0 transitions)

Phase-Modulated Nonresonant Laser Pulses Can Selectively Convert Enantiomers in a Racemic Mixture

DEFF Research Database (Denmark)

Thomas, Esben Folger; Henriksen, Niels Engholm

2017-01-01

-modulated, nonresonant, linearly polarized Gaussian laser pulses that can selectively deracemize a racemic mixture of 3D-oriented, 3,5-difluoro-3',5'-dibromobiphenyl (F2H3C6-C6H3Br2) molecules, the laser-induced dynamics of which are well studied experimentally. These results strongly suggest that designing a closed......Deracemization occurs when a racemic molecular mixture is transformed into a mixture containing an excess of a single enantiomer. Recent advances in ultrafast laser technology hint at the possibility of using shaped pulses to generate deracemization via selective enantiomeric conversion; however......, experimental implementation remains a challenge and has not yet been achieved. Here we suggest a simple, yet novel approach to laser-induced enantiomeric conversion based on dynamic Stark control. We demonstrate theoretically that current laser and optical technology can be used to generate a pair of phase...

Rapid Quadrupole-Time-of-Flight Mass Spectrometry Method Quantifies Oxygen-Rich Lignin Compound in Complex Mixtures

Science.gov (United States)

Boes, Kelsey S.; Roberts, Michael S.; Vinueza, Nelson R.

2018-03-01

Complex mixture analysis is a costly and time-consuming task facing researchers with foci as varied as food science and fuel analysis. When faced with the task of quantifying oxygen-rich bio-oil molecules in a complex diesel mixture, we asked whether complex mixtures could be qualitatively and quantitatively analyzed on a single mass spectrometer with mid-range resolving power without the use of lengthy separations. To answer this question, we developed and evaluated a quantitation method that eliminated chromatography steps and expanded the use of quadrupole-time-of-flight mass spectrometry from primarily qualitative to quantitative as well. To account for mixture complexity, the method employed an ionization dopant, targeted tandem mass spectrometry, and an internal standard. This combination of three techniques achieved reliable quantitation of oxygen-rich eugenol in diesel from 300 to 2500 ng/mL with sufficient linearity (R2 = 0.97 ± 0.01) and excellent accuracy (percent error = 0% ± 5). To understand the limitations of the method, it was compared to quantitation attained on a triple quadrupole mass spectrometer, the gold standard for quantitation. The triple quadrupole quantified eugenol from 50 to 2500 ng/mL with stronger linearity (R2 = 0.996 ± 0.003) than the quadrupole-time-of-flight and comparable accuracy (percent error = 4% ± 5). This demonstrates that a quadrupole-time-of-flight can be used for not only qualitative analysis but also targeted quantitation of oxygen-rich lignin molecules in complex mixtures without extensive sample preparation. The rapid and cost-effective method presented here offers new possibilities for bio-oil research, including: (1) allowing for bio-oil studies that demand repetitive analysis as process parameters are changed and (2) making this research accessible to more laboratories. [Figure not available: see fulltext.

Modelling time course gene expression data with finite mixtures of linear additive models.

Science.gov (United States)

Grün, Bettina; Scharl, Theresa; Leisch, Friedrich

2012-01-15

A model class of finite mixtures of linear additive models is presented. The component-specific parameters in the regression models are estimated using regularized likelihood methods. The advantages of the regularization are that (i) the pre-specified maximum degrees of freedom for the splines is less crucial than for unregularized estimation and that (ii) for each component individually a suitable degree of freedom is selected in an automatic way. The performance is evaluated in a simulation study with artificial data as well as on a yeast cell cycle dataset of gene expression levels over time. The latest release version of the R package flexmix is available from CRAN (http://cran.r-project.org/).

Linear-algebraic approach to electronic excitation of atoms and molecules by electron impact

International Nuclear Information System (INIS)

Collins, L.A.; Schneider, B.I.

1983-01-01

A linear-algebraic method, based on an integral equations formulation, is applied to the excitation of atoms and molecules by electron impact. Various schemes are devised for treating the one-electron terms that sometimes cause instabilities when directly incorporated into the solution matrix. These include introducing Lagrange undetermined multipliers and correlation terms. Good agreement between the method and other computational techniques is obtained for electron scattering for hydrogenic and Li-like atomic ions and for H 2 + in two- to five-state close-coupling calculations

Discrete unified gas kinetic scheme for all Knudsen number flows. III. Binary gas mixtures of Maxwell molecules

Science.gov (United States)

Zhang, Yue; Zhu, Lianhua; Wang, Ruijie; Guo, Zhaoli

2018-05-01

Recently a discrete unified gas kinetic scheme (DUGKS) in a finite-volume formulation based on the Boltzmann model equation has been developed for gas flows in all flow regimes. The original DUGKS is designed for flows of single-species gases. In this work, we extend the DUGKS to flows of binary gas mixtures of Maxwell molecules based on the Andries-Aoki-Perthame kinetic model [P. Andries et al., J. Stat. Phys. 106, 993 (2002), 10.1023/A:1014033703134. A particular feature of the method is that the flux at each cell interface is evaluated based on the characteristic solution of the kinetic equation itself; thus the numerical dissipation is low in comparison with that using direct reconstruction. Furthermore, the implicit treatment of the collision term enables the time step to be free from the restriction of the relaxation time. Unlike the DUGKS for single-species flows, a nonlinear system must be solved to determine the interaction parameters appearing in the equilibrium distribution function, which can be obtained analytically for Maxwell molecules. Several tests are performed to validate the scheme, including the shock structure problem under different Mach numbers and molar concentrations, the channel flow driven by a small gradient of pressure, temperature, or concentration, the plane Couette flow, and the shear driven cavity flow under different mass ratios and molar concentrations. The results are compared with those from other reliable numerical methods. The results show that the proposed scheme is an effective and reliable method for binary gas mixtures in all flow regimes.

Optimal mixture experiments

CERN Document Server

Sinha, B K; Pal, Manisha; Das, P

2014-01-01

The book dwells mainly on the optimality aspects of mixture designs. As mixture models are a special case of regression models, a general discussion on regression designs has been presented, which includes topics like continuous designs, de la Garza phenomenon, Loewner order domination, Equivalence theorems for different optimality criteria and standard optimality results for single variable polynomial regression and multivariate linear and quadratic regression models. This is followed by a review of the available literature on estimation of parameters in mixture models. Based on recent research findings, the volume also introduces optimal mixture designs for estimation of optimum mixing proportions in different mixture models, which include Scheffé’s quadratic model, Darroch-Waller model, log- contrast model, mixture-amount models, random coefficient models and multi-response model.  Robust mixture designs and mixture designs in blocks have been also reviewed. Moreover, some applications of mixture desig...

Supersonic molecular beam electric resonance spectroscopy and van der Waals molecules

International Nuclear Information System (INIS)

Luftman, H.S.

1982-09-01

A supersonic molecular beam electric resonance (MBER) spectrometer was built to study the radiofrequency spectra of weakly bound gas phase van der Waals molecules. The instrument and its operating characteristics are described in detail. Sample mass spectra of Ar-ClF gas mixtures are also presented as an illustration of the synthesis of van der Waals molecules. The Stark focusing process for linear polar molecules is discussed and computer-simulated using both second order perturbation and variational methods. Experimental refocusing spectra of OCS and ClF are studied and compared with these trajectory calculations. Though quantitative fitting is poor, there are strong qualitative indicators that the central part of a supersonic beam consists of molecules with a significantly greater population in the lowest energy rotational states than generally assumed. Flop in as opposed to flop out resonance signals for OCS are also numerically predicted and observed. The theoretical properties of the MBER spectrum for linear molecules are elaborated upon with special emphasis on line shape considerations. MBER spectra of OCS and ClF under a variety of conditions are presented and discussed in context to these predictions. There is some uncertainty expressed both in our own modeling and in the manner complex MBER spectra have been analyzed in the past. Finally, an electrostatic potential model is used to quantitatively describe the class of van der Waals molecules Ar-MX, where MX is an alkali halide. Energetics and equilibrium geometries are calculated. The validity of using an electrostatic model to predict van der Waals bond properties is critically discussed

Revival structures of linear molecules in a field-free alignment condition as probed by high-order harmonic generation

International Nuclear Information System (INIS)

Lee, G. H.; Kim, H. T.; Park, J. Y.; Nam, C. H.; Kim, T. K.; Lee, J. H.; Ihee, H.

2006-01-01

Revival structures (rotational coherence) of three linear molecules (N 2 , O 2 , and CO 2 ) in a field free alignment condition have been investigated using high-order harmonic generation. The harmonic yields of these molecules were measured in a pump-probe manner by using a weak femtosecond (fs) laser pulse for field-free alignment of molecules and another intense fs laser pulse for harmonic generation. The harmonic intensities from 23rd to 29th order with respect to the time delay between the pump and the probe pulses showed revival structures in the condition of a field-free alignment of molecules. While the revival structure of a N 2 molecule had one-fourth the period of the full revival time and different degrees of modulation among different fractional revival times, the revival structures of O 2 and CO 2 molecules showed one-eighth the periods of the full revival time and similar degrees of modulation among all fractional revival times. The revival structures could be interpreted in terms of the nature of the highest occupied molecular orbital and the total nuclear spin.

Application of the weak-field asymptotic theory to the analysis of tunneling ionization of linear molecules

DEFF Research Database (Denmark)

Madsen, Lars Bojer; Tolstikhin, Oleg I.; Morishita, Toru

2012-01-01

The recently developed weak-field asymptotic theory [ Phys. Rev. A 84 053423 (2011)] is applied to the analysis of tunneling ionization of a molecular ion (H2+), several homonuclear (H2, N2, O2) and heteronuclear (CO, HF) diatomic molecules, and a linear triatomic molecule (CO2) in a static...... electric field. The dependence of the ionization rate on the angle between the molecular axis and the field is determined by a structure factor for the highest occupied molecular orbital. This factor is calculated using a virtually exact discrete variable representation wave function for H2+, very accurate...... Hartree-Fock wave functions for the diatomics, and a Hartree-Fock quantum chemistry wave function for CO2. The structure factors are expanded in terms of standard functions and the associated structure coefficients, allowing the determination of the ionization rate for any orientation of the molecule...

Polarization and ellipticity of high-order harmonics from aligned molecules generated by linearly polarized intense laser pulses

International Nuclear Information System (INIS)

Le, Anh-Thu; Lin, C. D.; Lucchese, R. R.

2010-01-01

We present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned N 2 , CO 2 , and O 2 molecules generated by linearly polarized lasers. Within the rescattering model, the two polarization amplitudes of the harmonics are determined by the photo-recombination amplitudes for photons emitted with polarization parallel or perpendicular to the direction of the same returning electron wave packet. Our results show clear species-dependent polarization states, in excellent agreement with experiments. We further note that the measured polarization ellipse of the harmonic furnishes the needed parameters for a 'complete' experiment in molecules.

Method for separating gaseous mixtures of matter

International Nuclear Information System (INIS)

Schuster, E.; Kersting, A.

1979-01-01

Molecules to be separated from a mixture of matter of a chemical component are excited in a manner known per se by narrow-band light sources, and a chemical reaction partner for reacting with these molecules is admixed while supplied with energy by electromagnetic radiation or heating, and as additionally required for making chemical reactions possible. A method is described for separating gaseous mixtures of matter by exciting the molecules to be separated with laser radiation and causing the excited species to react chemically with a reaction partner. It may be necessary to supply additional energy to the reaction partner to make the chemical reaction possible. The method is applicable to the separation of hydrogen isotopes by the bromination of normal methanol in a mixture normal methanol and deuterated methanol; of uranium isotope by the reactions of UF 6 with SF 4 , SiCl 4 , HCl, or SO 2 ; and of boron isotopes by the reaction of BH 3 with NH 3

Identification of hydrometeor mixtures in polarimetric radar measurements and their linear de-mixing

Science.gov (United States)

Besic, Nikola; Ventura, Jordi Figueras i.; Grazioli, Jacopo; Gabella, Marco; Germann, Urs; Berne, Alexis

2017-04-01

The issue of hydrometeor mixtures affects radar sampling volumes without a clear dominant hydrometeor type. Containing a number of different hydrometeor types which significantly contribute to the polarimetric variables, these volumes are likely to occur in the vicinity of the melting layer and mainly, at large distance from a given radar. Motivated by potential benefits for both quantitative and qualitative applications of dual-pol radar, we propose a method for the identification of hydrometeor mixtures and their subsequent linear de-mixing. This method is intrinsically related to our recently proposed semi-supervised approach for hydrometeor classification. The mentioned classification approach [1] performs labeling of radar sampling volumes by using as a criterion the Euclidean distance with respect to five-dimensional centroids, depicting nine hydrometeor classes. The positions of the centroids in the space formed by four radar moments and one external parameter (phase indicator), are derived through a technique of k-medoids clustering, applied on a selected representative set of radar observations, and coupled with statistical testing which introduces the assumed microphysical properties of the different hydrometeor types. Aside from a hydrometeor type label, each radar sampling volume is characterized by an entropy estimate, indicating the uncertainty of the classification. Here, we revisit the concept of entropy presented in [1], in order to emphasize its presumed potential for the identification of hydrometeor mixtures. The calculation of entropy is based on the estimate of the probability (pi ) that the observation corresponds to the hydrometeor type i (i = 1,ṡṡṡ9) . The probability is derived from the Euclidean distance (di ) of the observation to the centroid characterizing the hydrometeor type i . The parametrization of the d → p transform is conducted in a controlled environment, using synthetic polarimetric radar datasets. It ensures balanced

Cosolvent effect on the dynamics of water in aqueous binary mixtures

Science.gov (United States)

Zhang, Xia; Zhang, Lu; Jin, Tan; Zhang, Qiang; Zhuang, Wei

2018-04-01

Water rotational dynamics in the mixtures of water and amphiphilic molecules, such as acetone and dimethyl sulfoxide (DMSO), measured by femtosecond infrared, often vary non-monotonically as the amphiphilic molecule's molar fraction changes from 0 to 1. Recent study has attributed the non-ideal water rotation with concentration in DMSO-water mixtures to different microscopic hydrophilic-hydrophobic segregation structure in water-rich and water-poor mixtures. Interestingly, the acetone molecule has very similar molecular structure to DMSO, but the extremum of the water rotational time in the DMSO-water mixtures significantly shifts to lower concentration and the rotation of water is much faster than those in acetone-water mixtures. The simulation results here shows that the non-ideal rotational dynamics of water in both mixtures are due to the frame rotation during the interval of hydrogen bond (HB) switchings. A turnover of the frame rotation with concentration takes place as the structure transition of mixture from the hydrogen bond percolation structure to the hydrophobic percolation structure. The weak acetone-water hydrogen bond strengthens the hydrophobic aggregation and accelerates the relaxation of the hydrogen bond, so that the structure transition takes places at lower concentration and the rotation of water is faster in acetone-water mixture than in DMSO-water mixture. A generally microscopic picture on the mixing effect on the water dynamics in binary aqueous mixtures is presented here.

Screening Mixtures of Small Molecules for Binding to Multiple Sites on the Surface Tetanus Toxin C Fragment by Bioaffinity NMR

International Nuclear Information System (INIS)

Cosman, M; Zeller, L; Lightstone, F C; Krishnan, V V; Balhorn, R

2002-01-01

The clostridial neurotoxins include the closely related tetanus (TeNT) and botulinum (BoNT) toxins. Botulinum toxin is used to treat severe muscle disorders and as a cosmetic wrinkle reducer. Large quantities of botulinum toxin have also been produced by terrorists for use as a biological weapon. Because there are no known antidotes for these toxins, they thus pose a potential threat to human health whether by an accidental overdose or by a hostile deployment. Thus, the discovery of high specificity and affinity compounds that can inhibit their binding to neural cells can be used as antidotes or in the design of chemical detectors. Using the crystal structure of the C fragment of the tetanus toxin (TetC), which is the cell recognition and cell surface binding domain, and the computational program DOCK, sets of small molecules have been predicted to bind to two different sites located on the surface of this protein. While Site-1 is common to the TeNT and BoNTs, Site-2 is unique to TeNT. Pairs of these molecules from each site can then be linked together synthetically to thereby increase the specificity and affinity for this toxin. Electrospray ionization mass spectroscopy was used to experimentally screen each compound for binding. Mixtures containing binders were further screened for activity under biologically relevant conditions using nuclear magnetic resonance (NMR) methods. The screening of mixtures of compounds offers increased efficiency and throughput as compared to testing single compounds and can also evaluate how possible structural changes induced by the binding of one ligand can influence the binding of the second ligand. In addition, competitive binding experiments with mixtures containing ligands predicted to bind the same site could identify the best binder for that site. NMR transfer nuclear Overhauser effect (trNOE) confirm that TetC binds doxorubicin but that this molecule is displaced by N-acetylneuraminic acid (sialic acid) in a mixture that

Probe-level linear model fitting and mixture modeling results in high accuracy detection of differential gene expression

Directory of Open Access Journals (Sweden)

Lemieux Sébastien

2006-08-01

Full Text Available Abstract Background The identification of differentially expressed genes (DEGs from Affymetrix GeneChips arrays is currently done by first computing expression levels from the low-level probe intensities, then deriving significance by comparing these expression levels between conditions. The proposed PL-LM (Probe-Level Linear Model method implements a linear model applied on the probe-level data to directly estimate the treatment effect. A finite mixture of Gaussian components is then used to identify DEGs using the coefficients estimated by the linear model. This approach can readily be applied to experimental design with or without replication. Results On a wholly defined dataset, the PL-LM method was able to identify 75% of the differentially expressed genes within 10% of false positives. This accuracy was achieved both using the three replicates per conditions available in the dataset and using only one replicate per condition. Conclusion The method achieves, on this dataset, a higher accuracy than the best set of tools identified by the authors of the dataset, and does so using only one replicate per condition.

Accounting for misclassification in electronic health records-derived exposures using generalized linear finite mixture models.

Science.gov (United States)

Hubbard, Rebecca A; Johnson, Eric; Chubak, Jessica; Wernli, Karen J; Kamineni, Aruna; Bogart, Andy; Rutter, Carolyn M

2017-06-01

Exposures derived from electronic health records (EHR) may be misclassified, leading to biased estimates of their association with outcomes of interest. An example of this problem arises in the context of cancer screening where test indication, the purpose for which a test was performed, is often unavailable. This poses a challenge to understanding the effectiveness of screening tests because estimates of screening test effectiveness are biased if some diagnostic tests are misclassified as screening. Prediction models have been developed for a variety of exposure variables that can be derived from EHR, but no previous research has investigated appropriate methods for obtaining unbiased association estimates using these predicted probabilities. The full likelihood incorporating information on both the predicted probability of exposure-class membership and the association between the exposure and outcome of interest can be expressed using a finite mixture model. When the regression model of interest is a generalized linear model (GLM), the expectation-maximization algorithm can be used to estimate the parameters using standard software for GLMs. Using simulation studies, we compared the bias and efficiency of this mixture model approach to alternative approaches including multiple imputation and dichotomization of the predicted probabilities to create a proxy for the missing predictor. The mixture model was the only approach that was unbiased across all scenarios investigated. Finally, we explored the performance of these alternatives in a study of colorectal cancer screening with colonoscopy. These findings have broad applicability in studies using EHR data where gold-standard exposures are unavailable and prediction models have been developed for estimating proxies.

Structure and Dynamics of Urea/Water Mixtures Investigated by Vibrational Spectroscopy and Molecular Dynamics Simulation

Science.gov (United States)

Carr, J. K.; Buchanan, L. E.; Schmidt, J. R.; Zanni, M. T.; Skinner, J. L.

2013-01-01

Urea/water is an archetypical “biological” mixture, and is especially well known for its relevance to protein thermodynamics, as urea acts as a protein denaturant at high concentration. This behavior has given rise to an extended debate concerning urea’s influence on water structure. Based on a variety of methods and of definitions of water structure, urea has been variously described as a structure-breaker, a structure-maker, or as remarkably neutral towards water. Because of its sensitivity to microscopic structure and dynamics, vibrational spectroscopy can help resolve these debates. We report experimental and theoretical spectroscopic results for the OD stretch of HOD/H2O/urea mixtures (linear IR, 2DIR, and pump-probe anisotropy decay) and for the CO stretch of urea-D4/D2O mixtures (linear IR only). Theoretical results are obtained using existing approaches for water, and a modification of a frequency map developed for acetamide. All absorption spectra are remarkably insensitive to urea concentration, consistent with the idea that urea only very weakly perturbs water structure. Both this work and experiments by Rezus and Bakker, however, show that water’s rotational dynamics are slowed down by urea. Analysis of the simulations casts doubt on the suggestion that urea immobilizes particular doubly hydrogen bonded water molecules. PMID:23841646

Superlattice configurations in linear chain hydrocarbon binary mixtures

Indian Academy of Sciences (India)

Unknown

Long-chain alkanes; binary mixtures; superlattices; discrete orientational changes. 1. Introduction ... tem and a model of superlattice configuration was proposed4, in terms of .... C18 system,4 the angle with value = 3⋅3° was seen to play an ...

Evaluation of synthetic linear motor-molecule actuation energetics

OpenAIRE

Brough, Branden; Northrop, Brian H.; Schmidt, Jacob J.; Tseng, Hsian-Rong; Houk, Kendall N.; Stoddart, J. Fraser; Ho, Chih-Ming

2006-01-01

By applying atomic force microscope (AFM)-based force spectroscopy together with computational modeling in the form of molecular force-field simulations, we have determined quantitatively the actuation energetics of a synthetic motor-molecule. This multidisciplinary approach was performed on specifically designed, bistable, redox-controllable [2]rotaxanes to probe the steric and electrostatic interactions that dictate their mechanical switching at the single-molecule level. The fusion of expe...

PREBIOTIC HYDROCARBON SYNTHESIS IN IMPACTING REDUCED ASTROPHYSICAL ICY MIXTURES

International Nuclear Information System (INIS)

Koziol, Lucas; Goldman, Nir

2015-01-01

We present results of prebiotic organic synthesis in shock-compressed reducing mixtures of simple ices from quantum molecular dynamics simulations extended to close to chemical equilibrium timescales. Given the relative abundance of carbon in reduced forms in astrophysical ices as well as the tendency of these mixtures to form complex hydrocarbons under the presence of external stimuli, it is possible that cometary impacts on a planetary surface could have yielded a larger array of prebiotic organic compounds than previously investigated. We find that the high pressures and temperatures due to shock compression yield a large assortment of carbon- and nitrogen-bonded extended structures that are highly reactive with short molecular lifetimes. Expansion and cooling causes these materials to break apart and form a wide variety of stable, potentially life-building compounds, including long-chain linear and branched hydrocarbons, large heterocyclic compounds, and a variety of different amines and exotic amino acids. Our results help provide a bottom-up understanding of hydrocarbon impact synthesis on the early Earth and its role in producing life-building molecules from simple starting materials

PREBIOTIC HYDROCARBON SYNTHESIS IN IMPACTING REDUCED ASTROPHYSICAL ICY MIXTURES

Energy Technology Data Exchange (ETDEWEB)

Koziol, Lucas; Goldman, Nir, E-mail: lucas.koziol@exxonmobil.com, E-mail: ngoldman@llnl.gov [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

2015-04-20

We present results of prebiotic organic synthesis in shock-compressed reducing mixtures of simple ices from quantum molecular dynamics simulations extended to close to chemical equilibrium timescales. Given the relative abundance of carbon in reduced forms in astrophysical ices as well as the tendency of these mixtures to form complex hydrocarbons under the presence of external stimuli, it is possible that cometary impacts on a planetary surface could have yielded a larger array of prebiotic organic compounds than previously investigated. We find that the high pressures and temperatures due to shock compression yield a large assortment of carbon- and nitrogen-bonded extended structures that are highly reactive with short molecular lifetimes. Expansion and cooling causes these materials to break apart and form a wide variety of stable, potentially life-building compounds, including long-chain linear and branched hydrocarbons, large heterocyclic compounds, and a variety of different amines and exotic amino acids. Our results help provide a bottom-up understanding of hydrocarbon impact synthesis on the early Earth and its role in producing life-building molecules from simple starting materials.

Measurement and Evaluation of Finger Tapping Movements Using Log-linearized Gaussian Mixture Networks

Directory of Open Access Journals (Sweden)

Masaru Yokoe

2009-03-01

Full Text Available This paper proposes a method to quantitatively measure and evaluate finger tapping movements for the assessment of motor function using log-linearized Gaussian mixture networks (LLGMNs. First, finger tapping movements are measured using magnetic sensors, and eleven indices are computed for evaluation. After standardizing these indices based on those of normal subjects, they are input to LLGMNs to assess motor function. Then, motor ability is probabilistically discriminated to determine whether it is normal or not using a classifier combined with the output of multiple LLGMNs based on bagging and entropy. This paper reports on evaluation and discrimination experiments performed on finger tapping movements in 33 Parkinson’s disease (PD patients and 32 normal elderly subjects. The results showed that the patients could be classified correctly in terms of their impairment status with a high degree of accuracy (average rate: 93:1 § 3:69% using 12 LLGMNs, which was about 5% higher than the results obtained using a single LLGMN.

Linear Ion Traps in Space: The Mars Organic Molecule Analyzer (MOMA) Instrument and Beyond

Science.gov (United States)

Arevalo, Ricardo; Brinckerhoff, William; Mahaffy, Paul; van Amerom, Friso; Danell, Ryan; Pinnick, Veronica; Li, Xiang; Hovmand, Lars; Getty, Stephanie; Grubisic, Andrej; Goesmann, Fred; Cottin, Hervé

2015-11-01

Historically, quadrupole mass spectrometer (QMS) instruments have been used to explore a wide survey of planetary targets in our solar system, from Venus (Pioneer Venus) to Saturn (Cassini-Huygens). However, linear ion trap (LIT) mass spectrometers have found a niche as smaller, versatile alternatives to traditional quadrupole analyzers.The core astrobiological experiment of ESA’s ExoMars Program is the Mars Organic Molecule Analyzer (MOMA) onboard the ExoMars 2018 rover. The MOMA instrument is centered on a linear (or 2-D) ion trap mass spectrometer. As opposed to 3-D traps, LIT-based instruments accommodate two symmetrical ion injection pathways, enabling two complementary ion sources to be used. In the case of MOMA, these two analytical approaches are laser desorption mass spectrometry (LDMS) at Mars ambient pressures, and traditional gas chromatography mass spectrometry (GCMS). The LIT analyzer employed by MOMA also offers: higher ion capacity compared to a 3-D trap of the same volume; redundant detection subassemblies for extended lifetime; and, a link to heritage QMS designs and assembly logistics. The MOMA engineering test unit (ETU) has demonstrated the detection of organics in the presence of wt.%-levels of perchlorate, effective ion enhancement via stored waveform inverse Fourier transform (SWIFT), and derivation of structural information through tandem mass spectrometry (MS/MS).A more progressive linear ion trap mass spectrometer (LITMS), funded by the NASA ROSES MatISSE Program, is being developed at NASA GSFC and promises to augment the capabilities of the MOMA instrument by way of: an expanded mass range (i.e., 20 - 2000 Da); detection of both positive and negative ions; spatially resolved (<1 mm) characterization of individual rock core layers; and, evolved gas analysis and GCMS with pyrolysis up to 1300° C (enabling breakdown of refractory phases). The Advanced Resolution Organic Molecule Analyzer (AROMA) instrument, being developed through NASA

Spectroscopic Diagnostics of Barrier Discharge Plasmas in Mixtures of Zinc Diiodide with Inert Gases

International Nuclear Information System (INIS)

Guivan, N.N.; Malinin, A.N.

2005-01-01

The spectral characteristics of the emission of gas discharge atmospheric pressure plasmas in mixtures of zinc diiodide vapor with inert gases (He, Ne, Ar, Kr, and Xe) are investigated. The formation of a gas discharge plasma and the excitation of the components of a working mixture were performed in a high-frequency (with a repetition frequency of sinusoidal voltage pulses of 100 kHz) barrier discharge. The gas discharge emission was analyzed in the spectral range 200-900 nm with a resolution of 0.05 nm. Emission bands of ZnI(B-X) exciplex molecules and I* 2 excimer molecules, lines of inert gases, and emission bands of XeI* exciplex molecules (in Xe-containing mixtures) were revealed. It is ascertained that the strongest emission of ZnI* molecules is observed in ZnI 2 /He(Ne) mixtures. The regularities in the spectral characteristics of the gas discharge plasma emission are considered

Study of two examples of non linear interaction of a laser wave with matter: laser-induced damage of dielectrics and non linear optical properties of organometallic molecules in solution

International Nuclear Information System (INIS)

Gaudry, Jean-Baptiste

2000-01-01

This research thesis reports the study of two mechanisms of non linear interaction of a laser wave with matter. More particularly, it reports the experimental investigation of non linear optical properties of organometallic molecules in solution, as well as the damage of perfect silica under laser irradiation by using simulation codes. As far as optical properties are concerned, the author highlights the influence of the electronic configuration of the metal present in the organometallic compound, and the influence of the ligand on the second-order non-linear response. As far as the simulation is concerned, some experimental results have been reproduced. This work can be useful for the investigation of the extrinsic damage of imperfect materials, and for the design of experiments of transient measurements of excited silica [fr

The Modified Enskog Equation for Mixtures

NARCIS (Netherlands)

Beijeren, H. van; Ernst, M.H.

1973-01-01

In a previous paper it was shown that a modified form of the Enskog equation, applied to mixtures of hard spheres, should be considered as the correct extension of the usual Enskog equation to the case of mixtures. The main argument was that the modified Enskog equation leads to linear transport

Discrete Velocity Models for Polyatomic Molecules Without Nonphysical Collision Invariants

Science.gov (United States)

Bernhoff, Niclas

2018-05-01

An important aspect of constructing discrete velocity models (DVMs) for the Boltzmann equation is to obtain the right number of collision invariants. Unlike for the Boltzmann equation, for DVMs there can appear extra collision invariants, so called spurious collision invariants, in plus to the physical ones. A DVM with only physical collision invariants, and hence, without spurious ones, is called normal. The construction of such normal DVMs has been studied a lot in the literature for single species, but also for binary mixtures and recently extensively for multicomponent mixtures. In this paper, we address ways of constructing normal DVMs for polyatomic molecules (here represented by that each molecule has an internal energy, to account for non-translational energies, which can change during collisions), under the assumption that the set of allowed internal energies are finite. We present general algorithms for constructing such models, but we also give concrete examples of such constructions. This approach can also be combined with similar constructions of multicomponent mixtures to obtain multicomponent mixtures with polyatomic molecules, which is also briefly outlined. Then also, chemical reactions can be added.

Superlattice configurations in linear chain hydrocarbon binary mixtures

Indian Academy of Sciences (India)

monoclinic, monoclinic-monoclinic) are realizable, because of discrete orientational changes in the alignment of molecules of -C28H58 hydrocarbon, through an angle , where = 1, 2, 3 … and angle has an average value of 3.3°.

Nuclear spin-spin coupling constants of linear carbon chains terminated by coronene molecules: a first principles study

International Nuclear Information System (INIS)

Oliveira, Joao Paulo Cavalcante; Mota, F. de Brito; Rivelino, Roberto

2011-01-01

Full text. Carbon nano wires made of long linear atomic chains have attracted considerable interest due to their potential applications in nano electronics. We report a density-functional-theory study of the nuclear spin-spin coupling constants for nano assemblies made of two coronene molecules bridged by carbon linear chains, considering distinct sizes and spin multiplicities. Also, we examine the effects of two terminal conformations (syn and anti) of the terminal anchor pieces on the magnetic properties of the carbon chains via 13 C NMR calculations. Our results reveal that simplified chemical models such as those based on cumulenes or polyynes are not appropriate to describe the linear chains with sp 2 terminations. For these types of atomic chains, the electronic ground state of the even-numbered chains can be singlet or triplet, whereas the ground state of the odd-numbered chains can be doublet or quartet. We discuss how the 13 C NMR chemical shift absorption is affected by increasing the size and changing the parity of the linear carbon chains. We have found that the J coupling constants between the carbon atoms in the linear chains present a well-defined pattern, in good accordance with our electronic structure calculations. For example, in the -C 4 - units we obtain couplings of 43.8, 114.5, 84.6, 114.5, and 43.8 Hz from one end to the other

Flow-alignment of bicellar lipid mixtures: orientations of probe molecules and membrane-associated biomacromolecules in lipid membranes studied with polarized light

KAUST Repository

Kogan, Maxim; Beke-Somfai, Tamá s; Nordé n, Bengt

2011-01-01

Bicelles are excellent membrane-mimicking hosts for a dynamic and structural study of solutes with NMR, but the magnetic fields required for their alignment are hard to apply to optical conditions. Here we demonstrate that bicellar mixtures can be aligned by shear forces in a Couette flow cell, to provide orientation of membrane-bound retinoic acid, pyrene and cytochrome c (cyt c) protein, conveniently studied with linear dichroism spectroscopy. © 2011 The Royal Society of Chemistry.

Effects of collisions on linear and non-linear spectroscopic line shapes

International Nuclear Information System (INIS)

Berman, P.R.

1978-01-01

A fundamental physical problem is the determination of atom-atom, atom-molecule and molecule-molecule differential and total scattering cross sections. In this work, a technique for studying atomic and molecular collisions using spectroscopic line shape analysis is discussed. Collisions occurring within an atomic or molecular sample influence the sample's absorptive or emissive properties. Consequently the line shapes associated with the linear or non-linear absorption of external fields by an atomic system reflect the collisional processes occurring in the gas. Explicit line shape expressions are derived characterizing linear or saturated absorption by two-or three-level 'active' atoms which are undergoing collisions with perturber atoms. The line shapes may be broadened, shifted, narrowed, or distorted as a result of collisions which may be 'phase-interrupting' or 'velocity-changing' in nature. Systematic line shape studies can be used to obtain information on both the differential and total active atom-perturber scattering cross sections. (Auth.)

Quantiles for Finite Mixtures of Normal Distributions

Science.gov (United States)

Rahman, Mezbahur; Rahman, Rumanur; Pearson, Larry M.

2006-01-01

Quantiles for finite mixtures of normal distributions are computed. The difference between a linear combination of independent normal random variables and a linear combination of independent normal densities is emphasized. (Contains 3 tables and 1 figure.)

Characterization of Interstellar Organic Molecules

International Nuclear Information System (INIS)

Gencaga, Deniz; Knuth, Kevin H.; Carbon, Duane F.

2008-01-01

Understanding the origins of life has been one of the greatest dreams throughout history. It is now known that star-forming regions contain complex organic molecules, known as Polycyclic Aromatic Hydrocarbons (PAHs), each of which has particular infrared spectral characteristics. By understanding which PAH species are found in specific star-forming regions, we can better understand the biochemistry that takes place in interstellar clouds. Identifying and classifying PAHs is not an easy task: we can only observe a single superposition of PAH spectra at any given astrophysical site, with the PAH species perhaps numbering in the hundreds or even thousands. This is a challenging source separation problem since we have only one observation composed of numerous mixed sources. However, it is made easier with the help of a library of hundreds of PAH spectra. In order to separate PAH molecules from their mixture, we need to identify the specific species and their unique concentrations that would provide the given mixture. We develop a Bayesian approach for this problem where sources are separated from their mixture by Metropolis Hastings algorithm. Separated PAH concentrations are provided with their error bars, illustrating the uncertainties involved in the estimation process. The approach is demonstrated on synthetic spectral mixtures using spectral resolutions from the Infrared Space Observatory (ISO). Performance of the method is tested for different noise levels.

excess molar volumes, and refractive index of binary mixtures

African Journals Online (AJOL)

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because (a) water molecules have hydroxyl group which can make stronger hydrogen bonding than methanol and (b) water molecules and glycerol have suitable kinetic energy for bulk volumes at high temperature. Thus, the mixture of glycerol + water have big excess molar volume than methanol. The hydrogen bonding ...

Optical characteristics of a RF DBD plasma jet in various {Ar}/ {O}_{2}Ar/O2 mixtures

Science.gov (United States)

Falahat, A.; Ganjovi, A.; Taraz, M.; Ravari, M. N. Rostami; Shahedi, A.

2018-02-01

In this paper, using the optical emission spectroscopy (OES) technique, the optical characteristics of a radiofrequency (RF) plasma jet are examined. The Ar/O2 mixture is taken as the operational gas and, the Ar percentage in the Ar/O2 mixture is varied from 70% to 95%. Using the optical emission spectrum analysis of the RF plasma jet, the excitation temperature is determined based on the Boltzmann plot method. The electron density in the plasma medium of the RF plasma jet is obtained by the Stark broadening of the hydrogen Balmer H_{β }. It is mostly seen that, the radiation intensity of Ar 4p→ 4s transitions at higher argon contributions in Ar/O2 mixture is higher. It is found that, at higher Ar percentages, the emission intensities from atomic oxygen (O) are higher and, the line intensities from the argon atoms and ions including O atoms linearly increase. It is observed that the quenching of Ar^{*} with O2 results in higher O species with respect to O2 molecules. In addition, at higher percentages of Ar in the Ar/O2 mixture, while the excitation temperature is decreased, the electron density is increased.

Natural convection in ternary mixtures

International Nuclear Information System (INIS)

Kremer, G.M.; Kai, L.

1981-01-01

The field equations for a mixture of a viscous fluid, a deformable solid and a non-viscous fluid are studied, based on a linearized theory proposed by Bowen. The fields of density of each constituent, temperature, velocity of each fluid and displacement of the solid are determined, for steady states flow of the mixture between two parallel planes and between two concentric cylinders which are maintained at diferent temperatures. (Author) [pt

Ultrasonic study of molecular interaction in binary liquid mixtures at ...

Indian Academy of Sciences (India)

The variation of these parameters with composition of the mixture helps us in understanding the nature and extent of interaction between unlike molecules in the mixtures. Further, theoretical values of ultrasonic speed were evaluated using theories and empirical relations. The relative merits of these theories and relations ...

Ejection of Coulomb Crystals from a Linear Paul Ion Trap for Ion-Molecule Reaction Studies.

Science.gov (United States)

Meyer, K A E; Pollum, L L; Petralia, L S; Tauschinsky, A; Rennick, C J; Softley, T P; Heazlewood, B R

2015-12-17

Coulomb crystals are being increasingly employed as a highly localized source of cold ions for the study of ion-molecule chemical reactions. To extend the scope of reactions that can be studied in Coulomb crystals-from simple reactions involving laser-cooled atomic ions, to more complex systems where molecular reactants give rise to multiple product channels-sensitive product detection methodologies are required. The use of a digital ion trap (DIT) and a new damped cosine trap (DCT) are described, which facilitate the ejection of Coulomb-crystallized ions onto an external detector for the recording of time-of-flight (TOF) mass spectra. This enables the examination of reaction dynamics and kinetics between Coulomb-crystallized ions and neutral molecules: ionic products are typically cotrapped, thus ejecting the crystal onto an external detector reveals the masses, identities, and quantities of all ionic species at a selected point in the reaction. Two reaction systems are examined: the reaction of Ca(+) with deuterated isotopologues of water, and the charge exchange between cotrapped Xe(+) with deuterated isotopologues of ammonia. These reactions are examples of two distinct types of experiment, the first involving direct reaction of the laser-cooled ions, and the second involving reaction of sympathetically-cooled heavy ions to form a mixture of light product ions. Extensive simulations are conducted to interpret experimental results and calculate optimal operating parameters, facilitating a comparison between the DIT and DCT approaches. The simulations also demonstrate a correlation between crystal shape and image shape on the detector, suggesting a possible means for determining crystal geometry for nonfluorescing ions.

Investigation on the structure of liquid N-methylformamide-dimethylsulfoxide mixtures

Science.gov (United States)

Cordeiro, João M. M.; Soper, Alan K.

2011-03-01

The structures of liquid mixtures of N-methylformamide (NMF) and dimethyl sulfoxide (DMSO) at two concentrations (80% and 50% NMF) are investigated using a combination of neutron diffraction augmented with isotopic substitution and empirical potential structure refinement simulations. The results indicate that the NMF and DMSO molecules are hydrogen-bonded to one another with a preference for NMF-DMSO hydrogen bonding, compared to the NMF-NMF ones. The liquid is orientationally structured as a consequence of these hydrogen bonds between molecules. NMF-DMSO dimers are very stable species in the bulk of the mixture. The structure of the dimers is such that the angle between the molecular dipole moments is around 60°. The NMF molecules are well solvated in DMSO with potential implications for peptides solvation in this solvent.

Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost

Energy Technology Data Exchange (ETDEWEB)

Scaglia, Barbara, E-mail: barbara.scaglia@unimi.it [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy); Nunes, Ramom Rachide; Rezende, Maria Olímpia Oliveira [Laboratório de Química Ambiental, Universidade de São Paulo, Instituto de Química de São Carlos, Avenida Trabalhador São Carlense, 400, São Carlos (Brazil); Tambone, Fulvia [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy); Adani, Fabrizio, E-mail: fabrizio.adani@unimi.it [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy)

2016-08-15

This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100–6000 mg carbon L{sup −1}. {sup 13}C CPMAS-NMR and GC–MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS {sup 13}CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R{sup 2} = − 0.85; p < 0.01, n = 6). - Highlights: • Vermicomposting converts waste into organic fertilizer. • Vermicomposts can have biostimulating effect for the presence of hormone-like molecules. • Auxine-like activity was associated to the vermicompost humic acid fraction (HA). • HA carboxylic acids and amino acids, were reported to act as auxin-like molecules. • A linear regression was found between molecules and auxin-like activity.

Electronic excitation of atoms and molecules by electron impact in a linear algebraic, separable potential approach

International Nuclear Information System (INIS)

Collins, L.A.; Schneider, B.I.

1984-01-01

The linear algebraic, separable potential approach is applied to the electronic excitation of atoms and molecules by electron impact. By representing the exchange and off-diagonal direct terms on a basis, the standard set of coupled inelastic equations is reduced to a set of elastic inhomogeneous equations. The procedure greatly simplifies the formulation by allowing a large portion of the problem to be handled by standard bound-state techniques and by greatly reducing the order of the scattering equations that must be solved. Application is made to the excitation of atomic hydrogen in the three-state close-coupling (1s, 2s, 2p) approximation. (author)

Dielectric properties of water in Triton X-100 (nonionic detergent)-water mixtures

International Nuclear Information System (INIS)

Asami, Koji

2007-01-01

Dielectric measurements were carried out for mixtures of Triton X-100 (TX, a nonionic detergent with a poly(ethylene oxide) chain) and water with or without electrolytes over a frequency range of 1 MHz to 10 GHz to study the structure and dynamics of water molecules in the mixtures. Dielectric relaxation was found above 100 MHz, being assigned to the dielectric relaxation of water. The intensity of the dielectric relaxation was proportional to the water content above 0 deg. C. Below the freezing temperature of bulk water, the relaxation intensity decreased at TX concentrations (C TX ) below 50 wt% at -10 deg. Cand below 60 wt% at -20 deg. Cbecause frozen water shifts the dielectric relaxation to a frequency region far below 1 MHz. This indicated that there is no bulk water at C TX above 50 wt% and that at least two water molecules per ethylene oxide (EO) unit are tightly associated with the ethylene oxide chain. The low-frequency conductivity of the mixtures of TX and electrolyte solutions was well represented by Bruggeman's mixture equation at C TX below 40 wt%, if two water molecules per EO unit form an insulating shell surrounding TX micelles

Investigation on the structure of liquid N-methylformamide-dimethylsulfoxide mixtures

Energy Technology Data Exchange (ETDEWEB)

Cordeiro, Joao M.M., E-mail: cordeiro@dfq.feis.unesp.br [ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX (United Kingdom); Soper, Alan K. [ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX (United Kingdom)

2011-03-18

Graphical abstract: Structure of liquid NMF and DMSO mixtures investigated using a combination of neutron diffraction techniques augmented with isotopic substitution and empirical potential structure refinement simulations. Research highlights: {yields} NMF-DMSO mixture is a well-structured liquid. {yields} The liquid structure is driven by strong hydrogen bonds. {yields} There is a preference for NMF-DMSO hydrogen bonding compared to the NMF-NMF. {yields} There are very stable NMF-DMSO dimers dispersed through the liquid. {yields} The peptide structure is very well solvated in DMSO. - Abstract: The structures of liquid mixtures of N-methylformamide (NMF) and dimethyl sulfoxide (DMSO) at two concentrations (80% and 50% NMF) are investigated using a combination of neutron diffraction augmented with isotopic substitution and empirical potential structure refinement simulations. The results indicate that the NMF and DMSO molecules are hydrogen-bonded to one another with a preference for NMF-DMSO hydrogen bonding, compared to the NMF-NMF ones. The liquid is orientationally structured as a consequence of these hydrogen bonds between molecules. NMF-DMSO dimers are very stable species in the bulk of the mixture. The structure of the dimers is such that the angle between the molecular dipole moments is around 60{sup o}. The NMF molecules are well solvated in DMSO with potential implications for peptides solvation in this solvent.

Investigation on the structure of liquid N-methylformamide-dimethylsulfoxide mixtures

International Nuclear Information System (INIS)

Cordeiro, Joao M.M.; Soper, Alan K.

2011-01-01

Graphical abstract: Structure of liquid NMF and DMSO mixtures investigated using a combination of neutron diffraction techniques augmented with isotopic substitution and empirical potential structure refinement simulations. Research highlights: → NMF-DMSO mixture is a well-structured liquid. → The liquid structure is driven by strong hydrogen bonds. → There is a preference for NMF-DMSO hydrogen bonding compared to the NMF-NMF. → There are very stable NMF-DMSO dimers dispersed through the liquid. → The peptide structure is very well solvated in DMSO. - Abstract: The structures of liquid mixtures of N-methylformamide (NMF) and dimethyl sulfoxide (DMSO) at two concentrations (80% and 50% NMF) are investigated using a combination of neutron diffraction augmented with isotopic substitution and empirical potential structure refinement simulations. The results indicate that the NMF and DMSO molecules are hydrogen-bonded to one another with a preference for NMF-DMSO hydrogen bonding, compared to the NMF-NMF ones. The liquid is orientationally structured as a consequence of these hydrogen bonds between molecules. NMF-DMSO dimers are very stable species in the bulk of the mixture. The structure of the dimers is such that the angle between the molecular dipole moments is around 60 o . The NMF molecules are well solvated in DMSO with potential implications for peptides solvation in this solvent.

Luminescent Characteristics of a Pulsed Discharge Plasma in Xe-KBr Mixture

Science.gov (United States)

Heneral, A. A.; Zhmenyak, Y. V.

2018-03-01

A mixture of xenon with a nontoxic halogen carrier Xe-KBr is used to create a plasma radiation source at the 282-nm transition of the XeBr* molecule excited by a high-voltage pulsed-periodic discharge. The luminescence spectra of the plasma of a longitudinal pulsed-periodic discharge in the Xe-KBr mixture at low pressures are studied experimentally. The most intense UV bands of exciplex XeBr* molecules are recorded in the spectral range of 250-350 nm. The spectral, temporal, and energetic characteristics of the radiation source are presented, as well as the dependence of the XeBr* exciplex molecule formation efficiency on the discharge excitation conditions. The optimal conditions for the excitation of UV radiation in the pulsed-periodic discharge plasma are determined.

Linear electric field time-of-flight ion mass spectrometer

Science.gov (United States)

Funsten, Herbert O [Los Alamos, NM; Feldman, William C [Los Alamos, NM

2008-06-10

A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.

Electron thermalization in rare gases and their mixtures

International Nuclear Information System (INIS)

Bronic, I.K.; Kimura, M.

1996-01-01

The time evolution and temperature dependence of electron energy distribution functions (EDFs) are studied in pure rare gases (He, Ne, Ar, Kr, Xe) as well as in their mixtures by using solutions of the Boltzmann equation. A clear difference between the gases having the Ramsauer endash Townsend (RT) minimum in the momentum-transfer cross section, (RT gases: Ar, Kr, and Xe), and those without the RT minimum (non-RT gases: He and Ne) is pointed out. The influence of the position and the depth of the RT minimum on the EDF and time evolution is studied for three different initial electron energies. A formula proposed for describing thermalization time in a mixture is tested on (i) a non-RT endash non-RT gas mixture, (ii) a RT endash non-RT mixture and (iii) a RT endash RT gas mixture. The linear combination of the reciprocal thermalization times in gas mixture with the component concentrations as weighting factors is found to be valid for gases with a similar energy dependence of the momentum-transfer cross section, σ m , and also for all rare-gas binary mixtures if the initial electron energy is sufficiently below the RT minimum. Conspicuous deviations from the linear relationship are observed in mixtures of gases whose energy dependence of σ m (or the stopping cross section) are different, and theoretical rationales for these findings are provided. copyright 1996 American Institute of Physics

Raman Spectroscopic Studies of Methane-Ethane Mixtures as a Function of Pressure

DEFF Research Database (Denmark)

Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

2001-01-01

Raman spectra of methane and methane-ethane mixtures (100, 85, and 49 mole % CH4) have been obtained as a function of pressure in the pressure range 0.1 to 15.3 MPaA (MPa absolute). For these mixtures methane nu (1) (symmetric C-H stretching) band positions are given as a function of pressure......; for pure methane they are in agreement with previous results. The new data on the methane nu (1) band position of ethane-containing mixtures clearly depend on the kind of molecules surrounding the vibrating methane molecule. The nu (1) band position decreases with increasing pressure; the stronger...... the dependency, the higher the content of ethane. The ethane nu (1) band position in the two mixtures showed the same kind of dependency, A qualitative explanation for this behavior is attempted, relating it to changes in van der Waals-type interactions on pressure....

Dielectric relaxation studies of some primary alcohols and their mixture with water

International Nuclear Information System (INIS)

Ahmad, S.S.; Yaqub, M.

2003-01-01

The complex dielectric constant of ethyl alcohol, methyl alcohol and 1- propanol and their mixtures with water of different concentration, (0 to 100% by weight) at the temperature of 303K has been evaluated, within the frequency range of (100KHz- 100 MHz). Moreover, the viscosity mu of each alcohol and its mixture with water have been measured at this temperature. The dielectric properties have been evaluated by Hartshorn and Ward apparatus. The purpose of this work is to study the influence of aliphatic group, size and shape on the extent of hydrogen bonding and also to obtain the thermodynamic data on hydrogen bond formation in the pure liquid state and its mixture. The width of the semicircle plot determines the distribution of average relaxation time. Dielectric relaxation time in pure alcohols and their water mixture has been calculated from the respected Cole-Cole plot and dielectric data. A single relaxation time of 117.16ps has been obtained for the molecules of pure methanol, whereas, the dielectric data of prophyl alcohol which indicates the viscosity water have been measured at the temperature 303 K. The dielectric properties in distribution of relaxation time, which is in good agreement with the Davidson-cole representation. The molecules in liquid mixture within frequency range, the mixture has more than one relaxation item, leading to the shortening of main relaxation time as compared with the pure alcohol and broadening of the complex permitivity spectra. The dependence of the dielectric relaxation on composition shows a remarkable behavior. Results are discussed in the light of H-bonded molecules. (author)

Shear viscosity of liquid mixtures: Mass dependence

International Nuclear Information System (INIS)

Kaushal, Rohan; Tankeshwar, K.

2002-06-01

Expressions for zeroth, second, and fourth sum rules of transverse stress autocorrelation function of two component fluid have been derived. These sum rules and Mori's memory function formalism have been used to study shear viscosity of Ar-Kr and isotopic mixtures. It has been found that theoretical result is in good agreement with the computer simulation result for the Ar-Kr mixture. The mass dependence of shear viscosity for different mole fraction shows that deviation from ideal linear model comes even from mass difference in two species of fluid mixture. At higher mass ratio shear viscosity of mixture is not explained by any of the emperical model. (author)

Shear viscosity of liquid mixtures Mass dependence

CERN Document Server

Kaushal, R

2002-01-01

Expressions for zeroth, second, and fourth sum rules of transverse stress autocorrelation function of two component fluid have been derived. These sum rules and Mori's memory function formalism have been used to study shear viscosity of Ar-Kr and isotopic mixtures. It has been found that theoretical result is in good agreement with the computer simulation result for the Ar-Kr mixture. The mass dependence of shear viscosity for different mole fraction shows that deviation from ideal linear model comes even from mass difference in two species of fluid mixture. At higher mass ratio shear viscosity of mixture is not explained by any of the emperical model.

Flows and chemical reactions in homogeneous mixtures

CERN Document Server

Prud'homme, Roger

2013-01-01

Flows with chemical reactions can occur in various fields such as combustion, process engineering, aeronautics, the atmospheric environment and aquatics. The examples of application chosen in this book mainly concern homogeneous reactive mixtures that can occur in propellers within the fields of process engineering and combustion: - propagation of sound and monodimensional flows in nozzles, which may include disequilibria of the internal modes of the energy of molecules; - ideal chemical reactors, stabilization of their steady operation points in the homogeneous case of a perfect mixture and c

XeBr excilamp based on a non-toxic component mixture

Energy Technology Data Exchange (ETDEWEB)

Kelman, V A; Shpenik, Yu O; Zhmenyak, Yu V, E-mail: mironkle@rambler.ru [Institute of Electron Physics, National Academy of Sciences of Ukraine, Universitetska 21, 88017 Uzhgorod (Ukraine)

2011-06-29

This paper presents the results of experimental studies on obtaining UV luminescence of XeBr* molecules at the excitation of a non-toxic Xe-CsBr gas-vapour mixture by a longitudinal pulse-periodic discharge. Effective UV emission yield of the exciplex XeBr* molecules (spectral maximum at 282 nm) is observed within a wide range of excitation conditions. The spectral distribution in the UV emission under the optimal excitation conditions does not differ essentially from that in other XeBr excilamps based on toxic components. The emission of the B {yields} X band of the XeBr* molecules provides the main contribution to the total power of the discharge UV emission. The determined average power of the UV emission for the experimental discharge tube is 12 W at an efficiency of 1%. Spectral, power-related and time-dependent parameters of the laboratory excilamp are presented for a wide range of excitation parameters. A new mechanism of exciplex molecule formation at the excitation of a rare gas/alkali halide vapour mixture is discussed.

XeBr excilamp based on a non-toxic component mixture

International Nuclear Information System (INIS)

Kelman, V A; Shpenik, Yu O; Zhmenyak, Yu V

2011-01-01

This paper presents the results of experimental studies on obtaining UV luminescence of XeBr* molecules at the excitation of a non-toxic Xe-CsBr gas-vapour mixture by a longitudinal pulse-periodic discharge. Effective UV emission yield of the exciplex XeBr* molecules (spectral maximum at 282 nm) is observed within a wide range of excitation conditions. The spectral distribution in the UV emission under the optimal excitation conditions does not differ essentially from that in other XeBr excilamps based on toxic components. The emission of the B → X band of the XeBr* molecules provides the main contribution to the total power of the discharge UV emission. The determined average power of the UV emission for the experimental discharge tube is 12 W at an efficiency of 1%. Spectral, power-related and time-dependent parameters of the laboratory excilamp are presented for a wide range of excitation parameters. A new mechanism of exciplex molecule formation at the excitation of a rare gas/alkali halide vapour mixture is discussed.

Acoustic properties of organic acid mixtures in water

Science.gov (United States)

Macavei, I.; Petrisor, V.; Auslaender, D.

1974-01-01

The variation of the rate of propagation of ultrasounds in organic acid mixtures in water points to structural changes caused by interactions that take place under conditions of thermal agitation, at different acid concentrations. At the same time, a difference is found in the changes in velocity as a function of the length of the carbon chain of the acids in the mixture as a result of their effect on the groups of water molecules associated by hydrogen bonds.

Formation of ultracold NaRb Feshbach molecules

International Nuclear Information System (INIS)

Wang, Fudong; He, Xiaodong; Li, Xiaoke; Zhu, Bing; Chen, Jun; Wang, Dajun

2015-01-01

We report the creation of ultracold bosonic 23 Na 87 Rb Feshbach molecules via magneto-association. By ramping the magnetic field across an interspecies Feshbach resonance (FR), at least 4000 molecules can be produced out of the near degenerate ultracold mixture. Fast loss due to inelastic atom–molecule collisions is observed, which limits the pure molecule number, after residual atoms removal, to 1700. The pure molecule sample can live for 21.8(8) ms in the optical trap, long enough for future molecular spectroscopy studies toward coherently transferring to the singlet ro-vibrational ground state, where these molecules are stable against chemical reaction and have a permanent electric dipole moment of 3.3 Debye. We have also measured the Feshbach molecule’s binding energy near the FR by the oscillating magnetic field method and found these molecules have a large closed-channel fraction. (paper)

Atomic Force Microscope Imaging of the Aggregation of Mouse Immunoglobulin G Molecules

Directory of Open Access Journals (Sweden)

Ke Xia

2003-01-01

Full Text Available Mouse immunoglobulin G (Ig G1 and the mixture of Ig G1 and Ig G2 deposited on mica were imaged with an atomic force microscope at room temperature and ambient pressure. At a concentration around 1.0mg/L, the molecules were well dispersed. 2~3 days after sample preparation, both Ig G1 and the mixture could self- assemble into different shapes and further form some types of local-ordered toroidal aggregations (monotoroidal, intercrossed toroidal, concentric toroidal, etc.. The number of monomers was not identical in the different toroidal aggregations but in a same circle, the shapes of polymer self-assembled by several monomolecules were found to be almost the same. There was difference between the aggregation behavior of Ig G1 and the mixture. The mechanism of Ig G molecule aggregation was ascribed to the “Y” shape and loops structure of Ig G molecule.

The structural and thermodynamical properties of binary ellipsoidal fluid mixture Gay-Berne interaction

Directory of Open Access Journals (Sweden)

M. Moradi

2007-06-01

Full Text Available  In this paper, a uniform classical fluid mixture comprising ellipsoidal molecules is studied. This mixture is composed of two types of ellipsoidal molecules interacting through the Gay-Berne potential with different sizes at temperature T. For this system, the Ornstein-Zernike equation using the Percus-Yevick closure relation is solved. Then the direct correlation function, pair correlation function and the pressure of the fluid at temperature T are calculated. The obtained results are in agreement with the previous theories and the results of molecular dynamic computer simulation.

Quasiresonant formation of dtμ mesic molecules in triple collisions

International Nuclear Information System (INIS)

Men'shikov, L.I.; Ponomarev, L.I.

1985-01-01

A quasiresonant mechanism of mesic molecules formation, in triple collisions of the type tμ+D 2 +D 2 → [(dtμ)d2e] * +D ν is considered. It is shown that at small resonance defects and big D 2 +T 2 mixture densities φ the rate of this process λ qr ∼ φ 2 and it is comparable with the rate λ r ∼ φ of the mesic molecules resonant formation in the reactions of the type tμ+D 2 → [(dtμ)d2e] ν *. The observable manifestations of the process considered and its role in the muon catalyzed fusion in deuterium-tritium mixture are discussed

VISCOSITY OF BINARY NON-ELECTROLYTE LIQUID MIXTURES: PREDICTION AND CORRELATION

Directory of Open Access Journals (Sweden)

Mirjana Lj. Kijevčanin

2008-11-01

Full Text Available The viscosity of 31 binary liquid mixtures containing diverse groups of organic compounds, determined at atmospheric pressure: alcohols, alkanes (cyclo and aliphatic, esters, aromatics, ketones etc., were calculated using two different approaches, correlative (with Teja-Rice and McAllister models and predictive by group contribution models (UNIFAC-VISCO, ASOG-VISCO and Grunberg-Nissan. The obtained results were analysed in terms of the applied approach and model, the structure of the investigated mixtures, the nature of components of the mixtures and the influence of alkyl chain length of the alcohol molecule.

Enantiomer-specific analysis of multi-component mixtures by correlated electron imaging-ion mass spectrometry

NARCIS (Netherlands)

Rafiee Fanood, M.M.; Ram, N.B.; Lehmann, C.S.; Powis, I.; Janssen, M.H.M.

2015-01-01

Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Here we show how

Monaural ICA of white noise mixtures is hard

DEFF Research Database (Denmark)

Hansen, Lars Kai; Petersen, Kaare Brandt

2003-01-01

Separation of monaural linear mixtures of `white' source signals is fundamentally ill-posed. In some situations it is not possible to find the mixing coefficients for the full `blind' problem. If the mixing coefficients are known, the structure of the source prior distribution determines the sour...... of white noise signals and give a set of `no go' cases.......Separation of monaural linear mixtures of `white' source signals is fundamentally ill-posed. In some situations it is not possible to find the mixing coefficients for the full `blind' problem. If the mixing coefficients are known, the structure of the source prior distribution determines the source...

Method of determination of muon catalyzed fusion parameters in H-T mixture

CERN Document Server

Bystritskij, V M

2002-01-01

A method for measurement of the muon catalyzed fusion parameters mu CF in the H-T mixture is proposed. The kinetics of the mu-atomic and mu-molecular processes preceding the pt reaction in the pt mu molecule is described. Analytical expressions are obtained for the yields and time distributions of gamma quanta and conversion muons formed in nuclear fusion reactions in pt mu molecules. It is shown that information on the desired parameters can be found from the joint analysis of the time distributions of gamma quanta and conversion muons obtained in experiments with the H-T mixture at three (and more) appreciable different atomic concentrations of tritium. The planned experiments with the H-T mixture at the meson facility PSI (Switzerland) are optimized to gain the precise information about the desired mu CF parameters

Method of determination of muon catalyzed fusion parameters in H-T mixture

International Nuclear Information System (INIS)

Bystritskij, V.M.; Gerasimov, V.V.

2002-01-01

A method for measurement of the muon catalyzed fusion parameters μCF in the H-T mixture is proposed. The kinetics of the mu-atomic and mu-molecular processes preceding the pt reaction in the ptμ molecule is described. Analytical expressions are obtained for the yields and time distributions of γ quanta and conversion muons formed in nuclear fusion reactions in ptμ molecules. It is shown that information on the desired parameters can be found from the joint analysis of the time distributions of γ quanta and conversion muons obtained in experiments with the H-T mixture at three (and more) appreciable different atomic concentrations of tritium. The planned experiments with the H-T mixture at the meson facility PSI (Switzerland) are optimized to gain the precise information about the desired μCF parameters

Latent log-linear models for handwritten digit classification.

Science.gov (United States)

Deselaers, Thomas; Gass, Tobias; Heigold, Georg; Ney, Hermann

2012-06-01

We present latent log-linear models, an extension of log-linear models incorporating latent variables, and we propose two applications thereof: log-linear mixture models and image deformation-aware log-linear models. The resulting models are fully discriminative, can be trained efficiently, and the model complexity can be controlled. Log-linear mixture models offer additional flexibility within the log-linear modeling framework. Unlike previous approaches, the image deformation-aware model directly considers image deformations and allows for a discriminative training of the deformation parameters. Both are trained using alternating optimization. For certain variants, convergence to a stationary point is guaranteed and, in practice, even variants without this guarantee converge and find models that perform well. We tune the methods on the USPS data set and evaluate on the MNIST data set, demonstrating the generalization capabilities of our proposed models. Our models, although using significantly fewer parameters, are able to obtain competitive results with models proposed in the literature.

Equivalence of truncated count mixture distributions and mixtures of truncated count distributions.

Science.gov (United States)

Böhning, Dankmar; Kuhnert, Ronny

2006-12-01

This article is about modeling count data with zero truncation. A parametric count density family is considered. The truncated mixture of densities from this family is different from the mixture of truncated densities from the same family. Whereas the former model is more natural to formulate and to interpret, the latter model is theoretically easier to treat. It is shown that for any mixing distribution leading to a truncated mixture, a (usually different) mixing distribution can be found so that the associated mixture of truncated densities equals the truncated mixture, and vice versa. This implies that the likelihood surfaces for both situations agree, and in this sense both models are equivalent. Zero-truncated count data models are used frequently in the capture-recapture setting to estimate population size, and it can be shown that the two Horvitz-Thompson estimators, associated with the two models, agree. In particular, it is possible to achieve strong results for mixtures of truncated Poisson densities, including reliable, global construction of the unique NPMLE (nonparametric maximum likelihood estimator) of the mixing distribution, implying a unique estimator for the population size. The benefit of these results lies in the fact that it is valid to work with the mixture of truncated count densities, which is less appealing for the practitioner but theoretically easier. Mixtures of truncated count densities form a convex linear model, for which a developed theory exists, including global maximum likelihood theory as well as algorithmic approaches. Once the problem has been solved in this class, it might readily be transformed back to the original problem by means of an explicitly given mapping. Applications of these ideas are given, particularly in the case of the truncated Poisson family.

Lubricating and waxy esters, I. Synthesis, crystallization, and melt behavior of linear monoesters.

Science.gov (United States)

Bouzidi, Laziz; Li, Shaojun; Di Biase, Steve; Rizvi, Syed Q; Narine, Suresh S

2012-01-01

Four pure jojoba wax-like esters (JLEs), having carbon chain length of 36, 40 (two isomers) and 44, were prepared by Steglish esterification of fatty acids (or acid chlorides) with fatty alcohols at room temperature. Calorimetric and diffraction data was used to elucidate the phase behavior of the esters. The primary thermal parameters (crystallization and melting temperatures) obtained from the DSC of the symmetrical molecules correspond well with the carbon numbers of the JLEs. However, the data also suggests that carbon number is not the only factor since the symmetry of the molecule also plays a significant role in the phase behavior. Overall, the JLEs show very little polymorphic activity at the experimental conditions used, suggesting that they are likely to transform the same way during melting as well as crystallization, a characteristic which may be useful in designing new waxes and lubricants. The XRD data clearly show that the solid phase in all samples consists of a mixture of a β-phase and a β'-phase; fully distinguishable by their characteristic diffraction peaks. Subtle differences between the subcell patterns and phase development of the samples were observed. Different layering of the samples was also observed, understandably because of the chain length differences between the compounds. The long spacings were perfectly linearly proportional to the number of carbon atoms. The length of the ester layers with n carbon atoms can be calculated by a formula similar to that used for the layers in linear alkane molecules. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Solvation of hydrocarbons in aqueous-organic mixtures

International Nuclear Information System (INIS)

Sedov, I.A.; Magsumov, T.I.; Solomonov, B.N.

2016-01-01

Highlights: • Thermodynamic functions of solvation in mixtures of water with acetone and acetonitrile are measured at T = 298.15 K. • Solvation of n-octane and toluene in aqueous-organic mixtures is studied. • When increasing water content, Gibbs free energies grow up steadily, while enthalpies have a maximum. • Hydrocarbons are preferentially solvated with organic cosolvent even in mixtures with rather high water content. • Acetonitrile suppresses the hydrophobic effect less than acetone. - Abstract: We study the solvation of two hydrocarbons, n-octane and toluene, in binary mixtures of water with organic cosolvents. Two polar aprotic cosolvents that are miscible with water in any proportions, acetonitrile and acetone, were considered. We determine the magnitudes of thermodynamic functions of dissolution and solvation at T = 298.15 K in the mixtures with various compositions. Solution calorimetry was used to measure the enthalpies of solution, and GC headspace analysis was applied to obtain limiting activity coefficients of solutes in the studied systems. For the first time, the enthalpies of solution of alkane in the mixtures with high water content were measured directly. We observed well-pronounced maxima of the dependencies of enthalpies of solvation from the composition of solvent and no maxima for the Gibbs free energies of solvation. Two factors are concluded to be important to explain the observed tendencies: high energy cost of reorganization of binary solvent upon insertion of solute molecules and preferential surrounding of hydrocarbons with the molecules of organic cosolvent. Enthalpy-entropy compensation leads to a steady growth of the Gibbs free energies with increasing water content. On the other hand, consideration of the plots of the Gibbs free energy against enthalpy of solvation clearly shows that the solvation properties are changed dramatically after addition of a rather small amount of organic cosolvents. It is shown that they

Study of different herbicide molecules for the control of durum wheat weed

Directory of Open Access Journals (Sweden)

Michele Perniola

2008-07-01

Full Text Available In order to enhance the chances to rotate the herbicide molecules, the effectiveness of a new molecule, pinoxaden, was tested, comparing it with other herbicides used in wheat weed control. The trial was carried out comparing the following herbicide mixtures: 1 no weed control treatment; 2 Tribenuron Methyl (TM; 3 Clodinafop (C; 4 Tribenuron Methyl + Clodinafop (TM+C; 5 Pinoxaden + clodinafop + propargile (PCP; 6 Pinoxaden + clodinafop + propargile + Triasulfuron (PCP+T; 7 Pinoxaden + clodinafop + propargile + absolute Ioxinil and Mecoprop (PCP+IM. The new PCP+T herbicides mixture didn’t differ statistically from the traditional TMC treatment in terms of effectiveness, but the agronomic result of the new mixture was totally satisfactory, even taking into account that the marketing of this mixture is not aimed to compete with other existing herbicides but to widen the chance to rotate active principles in time and space, in order to control the onset of resistance phenomena.

Study of different herbicide molecules for the control of durum wheat weed

Directory of Open Access Journals (Sweden)

Michele Perniola

Full Text Available In order to enhance the chances to rotate the herbicide molecules, the effectiveness of a new molecule, pinoxaden, was tested, comparing it with other herbicides used in wheat weed control. The trial was carried out comparing the following herbicide mixtures: 1 no weed control treatment; 2 Tribenuron Methyl (TM; 3 Clodinafop (C; 4 Tribenuron Methyl + Clodinafop (TM+C; 5 Pinoxaden + clodinafop + propargile (PCP; 6 Pinoxaden + clodinafop + propargile + Triasulfuron (PCP+T; 7 Pinoxaden + clodinafop + propargile + absolute Ioxinil and Mecoprop (PCP+IM. The new PCP+T herbicides mixture didn’t differ statistically from the traditional TMC treatment in terms of effectiveness, but the agronomic result of the new mixture was totally satisfactory, even taking into account that the marketing of this mixture is not aimed to compete with other existing herbicides but to widen the chance to rotate active principles in time and space, in order to control the onset of resistance phenomena.

Study of different herbicide molecules for the control of durum wheat weed

Directory of Open Access Journals (Sweden)

Vittorio Filì

2011-02-01

Full Text Available In order to enhance the chances to rotate the herbicide molecules, the effectiveness of a new molecule, pinoxaden, was tested, comparing it with other herbicides used in wheat weed control. The trial was carried out comparing the following herbicide mixtures: 1 no weed control treatment; 2 Tribenuron Methyl (TM; 3 Clodinafop (C; 4 Tribenuron Methyl + Clodinafop (TM+C; 5 Pinoxaden + clodinafop + propargile (PCP; 6 Pinoxaden + clodinafop + propargile + Triasulfuron (PCP+T; 7 Pinoxaden + clodinafop + propargile + absolute Ioxinil and Mecoprop (PCP+IM. The new PCP+T herbicides mixture didn’t differ statistically from the traditional TMC treatment in terms of effectiveness, but the agronomic result of the new mixture was totally satisfactory, even taking into account that the marketing of this mixture is not aimed to compete with other existing herbicides but to widen the chance to rotate active principles in time and space, in order to control the onset of resistance phenomena.

Linear kinetic theory and particle transport in stochastic mixtures. Third year and final report, June 15, 1993--December 14, 1996

International Nuclear Information System (INIS)

Pomraning, G.C.

1997-05-01

The goal in this research was to continue the development of a comprehensive theory of linear transport/kinetic theory in a stochastic mixture of solids and immiscible fluids. Such a theory should predict the ensemble average and higher moments, such as the variance, of the particle or energy density described by the underlying transport/kinetic equation. The statistics studied correspond to N-state discrete random variables for the interaction coefficients and sources, with N denoting the number of components in the mixture. The mixing statistics considered were Markovian as well as more general statistics. In the absence of time dependence and scattering, the theory is well developed and described exactly by the master (Liouville) equation for Markovian mixing, and by renewal equations for non-Markovian mixing. The intent of this research was to generalize these treatments to include both time dependence and scattering. A further goal of this research was to develop approximate, but simpler, models from any comprehensive theory. In particular, a specific goal was to formulate a renormalized transport/kinetic theory of the usual nonstochastic form, but with effective interaction coefficients and sources to account for the stochastic nature of the problem. In the three and one-half year period of research summarized in this final report, they have made substantial progress in the development of a comprehensive theory of kinetic processes in stochastic mixtures. This progress is summarized in 16 archival journal articles, 7 published proceedings papers, and 2 comprehensive review articles. In addition, 17 oral presentations were made describing these research results

Poisson Mixture Regression Models for Heart Disease Prediction.

Science.gov (United States)

Mufudza, Chipo; Erol, Hamza

2016-01-01

Early heart disease control can be achieved by high disease prediction and diagnosis efficiency. This paper focuses on the use of model based clustering techniques to predict and diagnose heart disease via Poisson mixture regression models. Analysis and application of Poisson mixture regression models is here addressed under two different classes: standard and concomitant variable mixture regression models. Results show that a two-component concomitant variable Poisson mixture regression model predicts heart disease better than both the standard Poisson mixture regression model and the ordinary general linear Poisson regression model due to its low Bayesian Information Criteria value. Furthermore, a Zero Inflated Poisson Mixture Regression model turned out to be the best model for heart prediction over all models as it both clusters individuals into high or low risk category and predicts rate to heart disease componentwise given clusters available. It is deduced that heart disease prediction can be effectively done by identifying the major risks componentwise using Poisson mixture regression model.

Poisson Mixture Regression Models for Heart Disease Prediction

Science.gov (United States)

Erol, Hamza

2016-01-01

Early heart disease control can be achieved by high disease prediction and diagnosis efficiency. This paper focuses on the use of model based clustering techniques to predict and diagnose heart disease via Poisson mixture regression models. Analysis and application of Poisson mixture regression models is here addressed under two different classes: standard and concomitant variable mixture regression models. Results show that a two-component concomitant variable Poisson mixture regression model predicts heart disease better than both the standard Poisson mixture regression model and the ordinary general linear Poisson regression model due to its low Bayesian Information Criteria value. Furthermore, a Zero Inflated Poisson Mixture Regression model turned out to be the best model for heart prediction over all models as it both clusters individuals into high or low risk category and predicts rate to heart disease componentwise given clusters available. It is deduced that heart disease prediction can be effectively done by identifying the major risks componentwise using Poisson mixture regression model. PMID:27999611

Investigating the discrimination potential of linear and nonlinear spectral multivariate calibrations for analysis of phenolic compounds in their binary and ternary mixtures and calculation pKa values

Science.gov (United States)

Rasouli, Zolaikha; Ghavami, Raouf

2016-08-01

Vanillin (VA), vanillic acid (VAI) and syringaldehyde (SIA) are important food additives as flavor enhancers. The current study for the first time is devote to the application of partial least square (PLS-1), partial robust M-regression (PRM) and feed forward neural networks (FFNNs) as linear and nonlinear chemometric methods for the simultaneous detection of binary and ternary mixtures of VA, VAI and SIA using data extracted directly from UV-spectra with overlapped peaks of individual analytes. Under the optimum experimental conditions, for each compound a linear calibration was obtained in the concentration range of 0.61-20.99 [LOD = 0.12], 0.67-23.19 [LOD = 0.13] and 0.73-25.12 [LOD = 0.15] μg mL- 1 for VA, VAI and SIA, respectively. Four calibration sets of standard samples were designed by combination of a full and fractional factorial designs with the use of the seven and three levels for each factor for binary and ternary mixtures, respectively. The results of this study reveal that both the methods of PLS-1 and PRM are similar in terms of predict ability each binary mixtures. The resolution of ternary mixture has been accomplished by FFNNs. Multivariate curve resolution-alternating least squares (MCR-ALS) was applied for the description of spectra from the acid-base titration systems each individual compound, i.e. the resolution of the complex overlapping spectra as well as to interpret the extracted spectral and concentration profiles of any pure chemical species identified. Evolving factor analysis (EFA) and singular value decomposition (SVD) were used to distinguish the number of chemical species. Subsequently, their corresponding dissociation constants were derived. Finally, FFNNs has been used to detection active compounds in real and spiked water samples.

Collision cross section calculations for polyatomic ions considering rotating diatomic/linear gas molecules

International Nuclear Information System (INIS)

Larriba-Andaluz, Carlos; Hogan, Christopher J.

2014-01-01

Structural characterization of ions in the gas phase is facilitated by measurement of ion collision cross sections (CCS) using techniques such as ion mobility spectrometry. Further information is gained from CCS measurement when comparison is made between measurements and accurately predicted CCSs for model ion structures and the gas in which measurements are made. While diatomic gases, namely molecular nitrogen and air, are being used in CCS measurement with increasingly prevalency, the majority of studies in which measurements are compared to predictions use models in which gas molecules are spherical or non-rotating, which is not necessarily appropriate for diatomic gases. Here, we adapt a momentum transfer based CCS calculation approach to consider rotating, diatomic gas molecule collisions with polyatomic ions, and compare CCS predictions with a diatomic gas molecule to those made with a spherical gas molecular for model spherical ions, tetra-alkylammonium ions, and multiply charged polyethylene glycol ions. CCS calculations are performed using both specular-elastic and diffuse-inelastic collisions rules, which mimic negligible internal energy exchange and complete thermal accommodation, respectively, between gas molecule and ion. The influence of the long range ion-induced dipole potential on calculations is also examined with both gas molecule models. In large part we find that CCSs calculated with specular-elastic collision rules decrease, while they increase with diffuse-inelastic collision rules when using diatomic gas molecules. Results clearly show the structural model of both the ion and gas molecule, the potential energy field between ion and gas molecule, and finally the modeled degree of kinetic energy exchange between ion and gas molecule internal energy are coupled to one another in CCS calculations, and must be considered carefully to obtain results which agree with measurements

Molecular dynamics study on the structure I clathrate-hydrate of methane + ethane mixture

International Nuclear Information System (INIS)

Erfan-Niya, Hamid; Modarress, Hamid; Zaminpayma, Esmaeil

2011-01-01

Molecular dynamics (MD) simulations are used to study the structure I stability of methane + ethane clathrate-hydrates at temperatures 273, 275 and 277 K. NVT- and NPT-ensembles are utilized in MD simulation, and each consists of 3 x 3 x 3 replica unit cells containing 46 water molecules which are considered as the host molecules and up to eight methane + ethane molecules considered as the guest molecules. In MD simulations for host-host interactions, the potential model used was a type of simple point charge (SPC) model, and for guest-guest and host-guest interactions the potential used was Lennard-Jones model. In the process of MD simulation, achieving equilibrium of the studied system was recognized by stability in calculated pressure for NVT-ensemble and volume for NPT-ensemble. To understand the characteristic configurations of the structure I hydrate, the radial distribution functions (RDFs) of host-host, host-guest and guest-guest molecules as well as other properties including kinetic energy, potential energy and total energy were calculated. The results show that guest molecules interaction with host molecules cannot decompose the hydrate structure, and these results are consistent with most previous experimental and theoretical investigations that methane + ethane mixtures form structure I hydrates over the entire mixture composition range.

Thermodynamic properties of fluid mixtures at high pressures and high temperatures. Application to high explosives and to phase diagrams of binary mixtures

International Nuclear Information System (INIS)

Pittion-Rossillon, Gerard

1982-01-01

The free energy for mixtures of about ten species which are chemically reacting is calculated. In order to have accurate results near the freezing line, excess properties are deduced from a modern statistical mechanics theory. Intermolecular potentials for like molecules are fitted to give good agreement with shock experiments in pure liquid samples, and mixture properties come naturally from the theory. The stationary Chapman-Jouguet detonation wave is calculated with a chemical equilibrium computer code and results are in good agreement with experiment for a lot of various explosives. One then study gas-gas equilibria in a binary mixture and show the extreme sensitivity of theoretical phase diagrams to the hypothesis of the model (author) [fr

Singlet oxygen reactivity in water-rich solvent mixtures

Directory of Open Access Journals (Sweden)

Cristina Sousa

2008-01-01

Full Text Available The 3-methylindole (3MI oxygenation sensitized by psoralen (PSO has been investigated in 100%, 20% and 5% O2-saturated water/dioxane (H2O/Dx mixtures. The lowering of the ¹O2* chemical rate when water (k chem∆3MI = 1.4 × 109 M-1 s-1 is replaced by deuterated water (k chem∆3MI = 1.9 × 108 M-1 s-1 suggests that hydrogen abstraction is involved in the rate determining step. A high dependence of the chemical rate constant on water concentration in H2O/Dx mixtures was found showing that water molecules are absolutely essential for the success of the 3MI substrate oxidation by ¹O2* in water-rich solvent mixtures.

Swelling characteristics of sand-bentonite mixtures under one-dimensional stress

International Nuclear Information System (INIS)

Cui, Hongbin; Sun, De'an; Matsuoka, Hajime; Xu Yongfu

2004-01-01

Based on the concept that the maximum water volume absorbed by unit volume of montmorillonite is constant, the swelling deformation of sand-bentonite mixtures is uniquely characterized using the void ratio of montmorillonite, which is defined by the ratio of water volume to montomorillonite volume. The relationship between the montmorillonite void ratio and overburden pressure at fully swelling is independent of the initial compaction condition and the sand-bentonite mixture ratio, and is a linear line in their log scale. When overburden pressure is large enough and/or the bentonite ratio of the mixture is small, the measured plots deviate from the line. A method for predicting the limited overburden pressure which is linearly correlated with the montmorillonite void ratio is proposed and verified using the concept of the skeleton void ratio. (author)

Measurement of linear attenuation coefficient of different materials

International Nuclear Information System (INIS)

Ali, M. M.

2013-07-01

In this research we study the linear attenuation coefficient from the materials concrete, brick, mixture concrete and iron. In the secondary standard dosimetry laboratory in Atomic Energy from different distance by use Cs-137 sours, chamber farmer 2675 A-600 cc-S/N 0511, and electrometer 2670 A-S/N 114. Found the value of linear attenuation coefficient of concert in the range 0.167 cm -1 , the brick in the range 0.063 -1 and mixture concrete and iron in the range 0.253cm -1 .(Author)

Evaluation of Physical Properties of Wax Mixtures Obtained From Recycling of Patterns Used in Precision Casting

Directory of Open Access Journals (Sweden)

Biernacki R.

2015-04-01

Full Text Available The study investigated the properties of selected certified mixtures used to make wax patterns for the production of precision castings for the aerospace industry. In addition, an assessment of the recycled mixtures consisting of certified wax materials recovered during autoclaving was carried out. Hardness was tested via a proposed method based on penetration, creep related deformation, bending strength and linear contraction. The hardness was studied on laboratory specimens and patterns made with the use of injection molding equipment. For these patterns, linear contraction was estimated at variable pressure and for different temperature injection parameters. Deformations connected with creep and resistance were evaluated on cylindrical specimens. Differences in creep resistance in relation to the hardness were observed depending on the type of pattern mixtures. Recycled mixture has a greater resistance and smaller linear contraction than certified mixtures used for making sprue, raisers and other parts of filler system.

Extraction of trivalent lanthanides and actinides by a synergistic mixture of thenoyltrifluoroacetone and a linear polyether

International Nuclear Information System (INIS)

Ensor, D.D.; Shah, A.H.

1984-01-01

Mixtures of a two component system, a linear polyether, 1,13-bis[8-quinolyl]-1,4,7,10,13-pentaoxatridecane, K-5, and thenoyltrifluoroacetone, HTTA, have been shown to exhibit synergistic character in the extraction of trivalent lanthanides and actinides. The effect of the addition of K-5 to the organic phase on the extractions of Ce(III), Eu(III), Tm(III), Am(III), Cm(III), Bk(III), and Cf(III) by HTTA in chloroform from 0.5M NaNO 3 at 25 0 C has been measured. These results indicate the extraction is enhanced by the formation of M(TTA) 3 K-5 adduct in the organic phase. The organic phase stability constants for the formation of these synergistic species have been calculated for all the metals studied. The magnitude of these organic phase stability constants for K-5 are similar to other common neutral donors. The order of stability does not follow the normal trend based on charge-to-radius ratio, but follows a pattern based on size, with Am(III) being the most stable

Kinetic Effects in the Self-Assembly of Pure and Mixed Tetradecyland Octadecylamine Molecules on Mica

Energy Technology Data Exchange (ETDEWEB)

Benitez, J.J.; Salmeron, M.

2005-09-21

The self-assembly of tetradecylamine (C14) and of mixtures of tetradecyl and octadecylamine (C18) molecules from chloroform solutions on mica has been studied using atomic force microscopy(AFM). For pure components self-assembly proceeds more slowly for C14 than for C18. In both cases after equilibrium is reached islands of tilted molecules cover a similar fraction of the surface. Images of films formed by mixtures of molecules acquired before equilibrium is reached (short ripening time at room temperature) show only islands with the height corresponding to C18 with many pores. After a long ripening time, when equilibrium is reached, islands of segregated pure components are formed.

The inherent dynamics of a molecular liquid: Geodesic pathways through the potential energy landscape of a liquid of linear molecules

Science.gov (United States)

Jacobson, Daniel; Stratt, Richard M.

2014-05-01

Because the geodesic pathways that a liquid follows through its potential energy landscape govern its slow, diffusive motion, we suggest that these pathways are logical candidates for the title of a liquid's "inherent dynamics." Like their namesake "inherent structures," these objects are simply features of the system's potential energy surface and thus provide views of the system's structural evolution unobstructed by thermal kinetic energy. This paper shows how these geodesic pathways can be computed for a liquid of linear molecules, allowing us to see precisely how such molecular liquids mix rotational and translational degrees of freedom into their dynamics. The ratio of translational to rotational components of the geodesic path lengths, for example, is significantly larger than would be expected on equipartition grounds, with a value that scales with the molecular aspect ratio. These and other features of the geodesics are consistent with a picture in which molecular reorientation adiabatically follows translation—molecules largely thread their way through narrow channels available in the potential energy landscape.

Quantum coherent π-electron rotations in a non-planar chiral molecule induced by using a linearly polarized UV laser pulse

Science.gov (United States)

Mineo, Hirobumi; Fujimura, Yuichi

2015-06-01

We propose an ultrafast quantum switching method of π-electron rotations, which are switched among four rotational patterns in a nonplanar chiral aromatic molecule (P)-2,2’- biphenol and perform the sequential switching among four rotational patterns which are performed by the overlapped pump-dump laser pulses. Coherent π-electron dynamics are generated by applying the linearly polarized UV pulse laser to create a pair of coherent quasidegenerated excited states. We also plot the time-dependent π-electron ring current, and discussed ring current transfer between two aromatic rings.

Hydrophobic hydration and anomalous excess partial molar volume of tert-butyl alcohol-water mixture studied by quasielastic neutron scattering

International Nuclear Information System (INIS)

Nakada, Masaru; Maruyama, Kenji; Misawa, Masakatsu; Yamamuro, Osamu

2007-01-01

Quasielastic neutron scattering has been used to investigate the hydration of alcohol clusters in tert-butyl alcohol-water mixture. The measurements were made in a range of alcohol concentration, x TBA , from 0.0 to 0.17 in mole fraction at 25degC. Fraction, α, of water molecules hydrated to fractal-surface of alcohol clusters in tert-butyl alcohol-water mixture was obtained as a function of alcohol concentration. Average hydration number N WS of tert-butyl alcohol molecule was derived from the value of α as a function of alcohol concentration. The value of N WS for an isolated alcohol molecule in water was 19-21. The anomalous excess partial molar volume of tert-butyl alcohol-water mixture was interpreted successfully by applying the same model with the same values of volume parameter as used for 1-propanol-water mixture, δ 1 (=-0.36 cm 3 ·mol -1 ) and δ 2 (=0.60 cm 3 ·mol -1 ). (author)

Optical trapping and Feshbach spectroscopy of an ultracold Rb-Cs mixture

International Nuclear Information System (INIS)

Pilch, K.

2009-01-01

We investigate quantum-mechanical interactions between ultracold rubidium and cesium in an optical trap at temperatures of a few micro kelvin. Our results provide, on the one hand, an experimental key to understand the collisional properties and, on the other hand, a tool to control the interspecies interactions. By performing loss measurements we locate several Feshbach resonances, which provide insight into the energy structure of weakly bound RbCs molecules near the dissociation threshold and allow for the production of such heteronuclear Feshbach molecules. In the future we will transfer these loosely-bound molecules into the absolute internal ground state. The availability of ultracold heteronuclear ground state molecules will open the door to investigate phenomena associated with ultracold polar quantum gases. In our new experimental set-up we are able to trap and cool rubidium and cesium atoms in their lowest internal states. First we load both species into a two-color magneto-optical trap, having full control over the single-species atom number. We extend the technique of degenerate Raman-sideband cooling to a two-color version, which is able to simultaneously cool and polarize both rubidium and cesium. Thereafter we load the atoms into a levitated crossed optical dipole trap. Because of the presence of the gradient magnetic field the trap is highly state selective and consequently provides perfect spin-polarization of the sample. Furthermore, a coincidence of the magnetic-moment-to-mass ratios of the two species allows for simultaneous levitation of both, which assures an almost perfect spatial overlap between the species. We perform Feshbach spectroscopy in two dierent spin channels of the mixture within a magnetic field ranging from 20 to 300 Gauss. In the lowest spin combination of the species we locate 23 interspecies Feshbach resonances, while in a higher spin mixture we find 2 resonances. The high number of resonances found within this range of

Stochastic radiative transfer model for mixture of discontinuous vegetation canopies

International Nuclear Information System (INIS)

Shabanov, Nikolay V.; Huang, D.; Knjazikhin, Y.; Dickinson, R.E.; Myneni, Ranga B.

2007-01-01

Modeling of the radiation regime of a mixture of vegetation species is a fundamental problem of the Earth's land remote sensing and climate applications. The major existing approaches, including the linear mixture model and the turbid medium (TM) mixture radiative transfer model, provide only an approximate solution to this problem. In this study, we developed the stochastic mixture radiative transfer (SMRT) model, a mathematically exact tool to evaluate radiation regime in a natural canopy with spatially varying optical properties, that is, canopy, which exhibits a structured mixture of vegetation species and gaps. The model solves for the radiation quantities, direct input to the remote sensing/climate applications: mean radiation fluxes over whole mixture and over individual species. The canopy structure is parameterized in the SMRT model in terms of two stochastic moments: the probability of finding species and the conditional pair-correlation of species. The second moment is responsible for the 3D radiation effects, namely, radiation streaming through gaps without interaction with vegetation and variation of the radiation fluxes between different species. We performed analytical and numerical analysis of the radiation effects, simulated with the SMRT model for the three cases of canopy structure: (a) non-ordered mixture of species and gaps (TM); (b) ordered mixture of species without gaps; and (c) ordered mixture of species with gaps. The analysis indicates that the variation of radiation fluxes between different species is proportional to the variation of species optical properties (leaf albedo, density of foliage, etc.) Gaps introduce significant disturbance to the radiation regime in the canopy as their optical properties constitute major contrast to those of any vegetation species. The SMRT model resolves deficiencies of the major existing mixture models: ignorance of species radiation coupling via multiple scattering of photons (the linear mixture model

Botanical drugs, synergy, and network pharmacology: forth and back to intelligent mixtures.

Science.gov (United States)

Gertsch, Jürg

2011-07-01

For centuries the science of pharmacognosy has dominated rational drug development until it was gradually substituted by target-based drug discovery in the last fifty years. Pharmacognosy stems from the different systems of traditional herbal medicine and its "reverse pharmacology" approach has led to the discovery of numerous pharmacologically active molecules and drug leads for humankind. But do botanical drugs also provide effective mixtures? Nature has evolved distinct strategies to modulate biological processes, either by selectively targeting biological macromolecules or by creating molecular promiscuity or polypharmacology (one molecule binds to different targets). Widely claimed to be superior over monosubstances, mixtures of bioactive compounds in botanical drugs allegedly exert synergistic therapeutic effects. Despite evolutionary clues to molecular synergism in nature, sound experimental data are still widely lacking to support this assumption. In this short review, the emerging concept of network pharmacology is highlighted, and the importance of studying ligand-target networks for botanical drugs is emphasized. Furthermore, problems associated with studying mixtures of molecules with distinctly different pharmacodynamic properties are addressed. It is concluded that a better understanding of the polypharmacology and potential network pharmacology of botanical drugs is fundamental in the ongoing rationalization of phytotherapy. © Georg Thieme Verlag KG Stuttgart · New York.

Numerical study of combustion initiation in a supersonic flow of H2-air mixture by resonance laser radiation

International Nuclear Information System (INIS)

Bezgin, L V; Kopchenov, V I; Kuleshov, P S; Titova, N S; Starik, A M

2012-01-01

A comparative analysis of the efficiency of approaches based on the exposure of reacting gas to resonance laser radiation to enhance combustion in a supersonic flow of H 2 -air mixture is conducted. The kinetic processes responsible for the intensification of chain reactions in premixed and non-premixed H 2 -air flows upon photodissociation of O 2 molecules by 193.3 nm laser radiation, excitation of these molecules to the singlet sigma state by laser photons with 762.346 nm wavelength and heating the mixture by laser radiation are analysed in a detailed manner. It is shown that both photochemical methods, photodissociation and excitation of O 2 molecules, are much more effective in shortening the ignition delay length than merely heating the mixture. For the premixed flow, the photodissociation of O 2 molecules ensures a slightly higher reduction in the ignition delay than the laser-induced excitation of molecular oxygen to the singlet sigma state. However, in the non-premixed flow the situation is inverted. The analysis shows that both photochemical methods make it possible to raise the efficiency of conversion of reactant chemical energy to thermal energy released during combustion compared with the method of heating the mixtures. (paper)

CONSOLIDATION AND COMPACTION OF POWDER MIXTURES .2. BINARY-MIXTURES OF DIFFERENT PARTICLE-SIZE FRACTIONS OF ALPHA-LACTOSE MONOHYDRATE

NARCIS (Netherlands)

RIEPMA, KA; VEENSTRA, J; DEBOER, AH; BOLHUIS, GK; ZUURMAN, K; LERK, CF; VROMANS, H

1991-01-01

Binary mixtures of different particle size fractions of alpha-lactose monohydrate were compacted into tablets. The results showed decreased crushing strengths and decreased internal specific surface areas of the tablets as compared with the values calculated by linear interpolation of the data

Resolved single-molecule detection of individual species within a mixture of anti-biotin antibodies using an engineered monomeric nanopore.

Science.gov (United States)

Fahie, Monifa; Chisholm, Christina; Chen, Min

2015-02-24

Oligomeric protein nanopores with rigid structures have been engineered for the purpose of sensing a wide range of analytes including small molecules and biological species such as proteins and DNA. We chose a monomeric β-barrel porin, OmpG, as the platform from which to derive the nanopore sensor. OmpG is decorated with seven flexible loops that move dynamically to create a distinct gating pattern when ionic current passes through the pore. Biotin was chemically tethered to the most flexible one of these loops. The gating characteristic of the loop's movement in and out of the porin was substantially altered by analyte protein binding. The gating characteristics of the pore with bound targets were remarkably sensitive to molecular identity, even providing the ability to distinguish between homologues within an antibody mixture. A total of five gating parameters were analyzed for each analyte to create a unique fingerprint for each biotin-binding protein. Our exploitation of gating noise as a molecular identifier may allow more sophisticated sensor design, while OmpG's monomeric structure greatly simplifies nanopore production.

Interfacial tensions of binary mixtures of ethanol with octane, decane, dodecane, and tetradecane

International Nuclear Information System (INIS)

Mejia, Andres; Cartes, Marcela; Segura, Hugo

2011-01-01

Highlights: → Experimental interfacial tensions in binary mixtures with aneotropic behavior. → Experimental interfacial tensions for ethanol + hydrocarbon mixtures. → Aneotropic displacement in ethanol mixtures. - Abstract: This contribution is devoted to the experimental characterization of interfacial tensions of a representative group of binary mixtures pertaining to the (ethanol + linear hydrocarbon) series (i.e. octane, decane, dodecane, and tetradecane). Experimental measurements were isothermically performed using a maximum differential bubble pressure technique, which was applied over the whole mole fraction range and over the temperature range 298.15 K < T/K < 318.15 K. Experimental results show that the interfacial tensions of (ethanol + octane or decane) negatively deviate from the linear behavior and that sharp minimum points on concentration, or aneotropes, are observed for each isotherm. The interfacial tensions of (ethanol + dodecane or tetradecane), in turn, are characterized by combined deviations from the linear behavior, and inflecting behavior observed on concentration for each isotherm. The experimental evidence also shows that these latter mixtures are close to exhibit aneotropy. For the case of (ethanol + octane or decane) mixtures, aneotropy was clearly induced by the similarity of the interfacial tension values of the constituents. The inflecting behavior of the interfacial tensions of (ethanol + dodecane or tetradecane), in turn, was observed in the vicinity of the coordinates of the critical point of these mixtures, thus pointing to the fact that the quasi-aneotropic singularity that affects these mixtures was provoked by the proximity of an immiscibility gap of the liquid phase. Finally, the experimental data of interfacial tensions were smoothed with the Scott-Myers expansion, from which it is possible to conclude that the observed aneotropic concentrations weakly depend on temperature for all the analyzed mixtures.

The wetting of planar solid surfaces by symmetric binary mixtures near bulk gas-liquid coexistence

International Nuclear Information System (INIS)

Woywod, Dirk; Schoen, Martin

2004-01-01

We investigate the wetting of planar, nonselective solid substrates by symmetric binary mixtures where the attraction strength between like molecules of components A and B is the same, that is ε AA ε BB AB vertical bar ≤ vertical bar ε AA vertical bar, that is by varying the attraction between a pair of unlike molecules. By means of mean-field lattice density functional calculations we observe a rich wetting behaviour as a result of the interplay between ε AB and the attraction of fluid molecules by the solid substrate ε W . In accord with previous studies we observe complete wetting only above the critical end point if the bulk mixture exhibits a moderate to weak tendency to liquid-liquid phase separation even for relatively strong fluid-substrate attraction. However, in this case layering transitions may arise below the temperature of the critical end point. For strongly phase separating mixtures complete wetting is observed for all temperatures T ≥0 along the line of discontinuous phase transitions in the bulk

Nonlinear Structured Growth Mixture Models in M"plus" and OpenMx

Science.gov (United States)

Grimm, Kevin J.; Ram, Nilam; Estabrook, Ryne

2010-01-01

Growth mixture models (GMMs; B. O. Muthen & Muthen, 2000; B. O. Muthen & Shedden, 1999) are a combination of latent curve models (LCMs) and finite mixture models to examine the existence of latent classes that follow distinct developmental patterns. GMMs are often fit with linear, latent basis, multiphase, or polynomial change models…

Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

Energy Technology Data Exchange (ETDEWEB)

Theodorakis, P E [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Avgeropoulos, A [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Senda del Rey 9, 28040 Madrid (Spain); Kosmas, M [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece); Vlahos, C [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)

2007-11-21

The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

Science.gov (United States)

Theodorakis, P. E.; Avgeropoulos, A.; Freire, J. J.; Kosmas, M.; Vlahos, C.

2007-11-01

The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

International Nuclear Information System (INIS)

Theodorakis, P E; Avgeropoulos, A; Freire, J J; Kosmas, M; Vlahos, C

2007-01-01

The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results

Molecules with linear pi-conjugated pathways between all substituents : Omniconjugation

NARCIS (Netherlands)

van der Veen, M.H.; Rispens, M.T; Jonkman, H.T.; Hummelen, J.C.

In this paper, omniconjugation is introduced as a topological phenomenon in pi-conjugated systems. Omniconjugated molecules are defined by the fact that they provide direct and fully pi-conjugated pathways between all subdstituents attached to them. Surprisingly, until now such topologies have never

Molecules with Linear π-Conjugated Pathways between All Substituents : Omniconjugation

NARCIS (Netherlands)

Veen, Marleen H. van der; Rispens, Minze T.; Jonkman, Harry T.; Hummelen, Jan C.

2004-01-01

In this paper, omniconjugation is introduced as a topological phenomenon in π-conjugated systems. Omniconjugated molecules are defined by the fact that they provide direct and fully π-conjugated pathways between all substituents attached to them. Surprisingly, until now such topologies have never

Equation of state of strongly coupled plasma mixtures

International Nuclear Information System (INIS)

DeWitt, H.E.

1984-01-01

Thermodynamic properties of strongly coupled (high density) plasmas of mixtures of light elements have been obtained by Monte Carlo simulations. For an assumed uniform charge background the equation of state of ionic mixtures is a simple extension of the one-component plasma EOS. More realistic electron screening effects are treated in linear response theory and with an appropriate electron dielectric function. Results have been obtained for the ionic pair distribution functions, and for the electric microfield distribution

Catanionic mixtures forming gemini-like amphiphiles.

Science.gov (United States)

Sakai, Hideki; Okabe, Yuji; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko

2011-01-01

The properties of aqueous mixtures of cationic species with alkyl dicarboxylic acid compounds have been studied. The cationic compounds used in this study were tertiary amine-type N-methyl-N-(2,3-dioxypropyl)hexadecylamine (C16amine) and quaternary ammonium-type N,N-dimethyl-N-(2,3-dioxypropyl)hexadecylammonium chloride (C16Q). The alkyl dicarboxylic acid compounds used were HOOC(CH(2))(10)COOH (C12H) and its sodium salt (C12Na). Three aqueous mixtures were examined in this study: (System I) C16amine + C12H, (System II) C16Q + C12Na, and (System III) C16Q + C12H. The solution pH was set at 12 for System III. The combination of (1)H-NMR and mass spectroscopy data has suggested that a stoichiometric complex is formed in the aqueous solutions at a mole fraction of C12H (or C12Na) = 0.33. Here, the C12H (or C12Na) molecule added to the system bridges two cationic molecules, like a spacer of gemini surfactants. In fact, the static surface tensiometry has demonstrated that the stoichiometric complex behaves as gemini-like amphiphiles in aqueous solutions. Our current study offers a possible way for easily preparing gemini surfactant systems.

Quiralidade em moléculas e cristais Chirality at molecules and crystals

Directory of Open Access Journals (Sweden)

Ayres Guimarães Dias

2009-01-01

Full Text Available The present contribution describes some concepts of stereochemistry and chirality in molecules and crystals. This paper also reports on the development of a simple and fast experiment to prepare and recognize conglomerate and true racemate of tartaric acid produced by mechanic mixture of commercial enantiomers and recristalization. Optical activity and melting point of mixtures are also used in the analysis.

Determination of phenacetin and salophen analgetics in solid binary mixtures with caffeine by infrared linear dichroic and Raman spectroscopy.

Science.gov (United States)

Koleva, Bojidarka B; Kolev, Tsonko M; Tsalev, Dimiter L; Spiteller, Michael

2008-01-22

Quantitative infrared (IR) and Raman spectroscopic approach for determination of phenacetin (Phen) and salophen (Salo) in binary solid mixtures with caffeine: phenacetin/caffeine (System 1) and salophen/caffeine (System 2) is presented. Absorbance ratios of 746 cm(-1) or 721 cm(-1) peaks (characteristic for each of determined compounds in the Systems 1 and 2) to 1509 cm(-1) and 1616 cm(-1) (attributed to Phen and Salo, respectively) were used. The IR spectroscopy gives confidence of 98.9% (System 1) and 98.3% (System 2), while the Raman spectroscopic data are with slightly higher confidence of 99.1% for both systems. The limits of detection for the compounds studied were 0.013 and 0.012 mole fraction for IR and Raman methods, respectively. Solid-state linear dichroic infrared (IR-LD) spectral analysis of solid mixtures was carried out with a view to obtaining experimental IR spectroscopic assignment of the characteristic IR bands of both determined compounds. The orientation technique as a nematic liquid crystal suspension was used, combined with the so-called reducing-difference procedure for polarized spectra interpretation. The possibility for obtaining supramolecular stereo structural information for Phen and Salo by comparing spectroscopic and crystallographic data has also been shown. An independent high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis was performed for comparison and validation of vibrational spectroscopy data. Applications to 10 tablets of commercial products APC and Sedalgin are given.

The interaction of insulin, glucose, and insulin-glucose mixtures with a phospholipid monolayer.

Science.gov (United States)

Shigenobu, Hayato; McNamee, Cathy E

2012-12-15

We determined how glucose or insulin interacts with a phospholipid monolayer at the air/water interface and explained these mechanisms from a physico-chemical point of view. The 1,2-dipalmitoyl-2-sn-glycero-3-phosphatidylcholine (DPPC) monolayer at an air/water interface acted as a model membrane, which allowed the effect of the molecular packing density in the monolayer on the interactions to be determined. The interaction of glucose, insulin, and a mixture of glucose and insulin to the DPPC monolayer were investigated via surface pressure-area per molecule Langmuir isotherms and fluorescence microscopy. Glucose adsorbed to the underside of the DPPC monolayer, while insulin was able to penetrate through the monolayer when the phospholipid molecules were not densely packed. The presence of a mixture of insulin and glucose affected the molecular packing in the DPPC monolayer differently than the pure insulin or glucose solutions, and the glucose-insulin mixture was seen to be able to penetrate through the monolayer. These results indicated that glucose and insulin interact with one another, giving a material that may then transported through a pore in the monolayer or through the spaces between the molecules of the monolayer. Copyright © 2012 Elsevier Inc. All rights reserved.

The synthesis and properties of linear A-π-D-π-A type organic small molecule containing diketopyrrolopyrrole terminal units

Science.gov (United States)

Zhang, Shanshan; Niu, Qingfen; Sun, Tao; Li, Yang; Li, Tianduo; Liu, Haixia

2017-08-01

A novel linear A-π-D-π-A-type organic small molecule Ph2(PDPP)2 consisting diketopyrrolopyrrole (DPP) as acceptor unit, biphenylene as donor unit and acetylene unit as π-linkage has been successfully designed and synthesized. Its corresponding thermal, photophysical and electrochemical properties as well as the photoinduced charge-separation process were investigated. Ph2(PDPP)2 exhibits high thermal stability and it can be soluble in common organic solvents such as chloroform and tetrahydrofuran. The photophysical properties show that DPP2Ph2 harvests sunlight over the entire visible spectrum range in the thin-film state (300-800 nm). DPP2Ph2 has lower band gaps and appropriate energy levels to satisfy the requirement of solution-processable organic solar cells. The efficient photoinduced charge separation process was clearly observed between DPP2Ph2 with PC61BM and the Ksv value was found to be as high as 2.13 × 104 M- 1. Therefore, these excellent properties demonstrate that the designed A-π-D-π-A-type small molecule Ph2(PDPP)2 is the prospective candidate as donor material for organic photovoltaic material.

ReaxFF molecular dynamics simulation of intermolecular structure formation in acetic acid-water mixtures at elevated temperatures and pressures

Science.gov (United States)

Sengul, Mert Y.; Randall, Clive A.; van Duin, Adri C. T.

2018-04-01

The intermolecular structure formation in liquid and supercritical acetic acid-water mixtures was investigated using ReaxFF-based molecular dynamics simulations. The microscopic structures of acetic acid-water mixtures with different acetic acid mole fractions (1.0 ≥ xHAc ≥ 0.2) at ambient and critical conditions were examined. The potential energy surface associated with the dissociation of acetic acid molecules was calculated using a metadynamics procedure to optimize the dissociation energy of ReaxFF potential. At ambient conditions, depending on the acetic acid concentration, either acetic acid clusters or water clusters are dominant in the liquid mixture. When acetic acid is dominant (0.4 ≤ xHAc), cyclic dimers and chain structures between acetic acid molecules are present in the mixture. Both structures disappear at increased water content of the mixture. It was found by simulations that the acetic acid molecules released from these dimer and chain structures tend to stay in a dipole-dipole interaction. These structural changes are in agreement with the experimental results. When switched to critical conditions, the long-range interactions (e.g., second or fourth neighbor) disappear and the water-water and acetic acid-acetic acid structural formations become disordered. The simulated radial distribution function for water-water interactions is in agreement with experimental and computational studies. The first neighbor interactions between acetic acid and water molecules are preserved at relatively lower temperatures of the critical region. As higher temperatures are reached in the critical region, these interactions were observed to weaken. These simulations indicate that ReaxFF molecular dynamics simulations are an appropriate tool for studying supercritical water/organic acid mixtures.

Collective dynamics in dense fluid mixtures

International Nuclear Information System (INIS)

Sinha, S.

1992-01-01

This thesis deals with the short wavelength collective dynamics of dense binary fluid mixtures. The analysis shows that at the level of linearized generalized hydrodynamics, the longitudinal modes of the system separates essentially into two parts - one involves the coupling of partial density fluctuations of the two species and the other involves coupling of longitudinal momentum and temperature fluctuations. The authors have shown that the coupling of longitudinal momentum and temperature fluctuations leads to an adequate description of sound propagation in such systems. In particular, they show that structural disorder controls the trapping of sound waves in dense mixtures. The coupling of the partial density fluctuations of the two species leads to a simple description of the partial dynamic structure factors. The results are in agreement with the molecular dynamics simulations of soft sphere mixtures. The partial density fluctuations are the slowest decaying fluctuations on molecular length scales and it turns out that nonlinear coupling of these slow modes leads to important corrections to the long time behavior of the time correlation functions determining the shear viscosity in dense mixtures

Artificial neural network and classical least-squares methods for neurotransmitter mixture analysis.

Science.gov (United States)

Schulze, H G; Greek, L S; Gorzalka, B B; Bree, A V; Blades, M W; Turner, R F

1995-02-01

Identification of individual components in biological mixtures can be a difficult problem regardless of the analytical method employed. In this work, Raman spectroscopy was chosen as a prototype analytical method due to its inherent versatility and applicability to aqueous media, making it useful for the study of biological samples. Artificial neural networks (ANNs) and the classical least-squares (CLS) method were used to identify and quantify the Raman spectra of the small-molecule neurotransmitters and mixtures of such molecules. The transfer functions used by a network, as well as the architecture of a network, played an important role in the ability of the network to identify the Raman spectra of individual neurotransmitters and the Raman spectra of neurotransmitter mixtures. Specifically, networks using sigmoid and hyperbolic tangent transfer functions generalized better from the mixtures in the training data set to those in the testing data sets than networks using sine functions. Networks with connections that permit the local processing of inputs generally performed better than other networks on all the testing data sets. and better than the CLS method of curve fitting, on novel spectra of some neurotransmitters. The CLS method was found to perform well on noisy, shifted, and difference spectra.

General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

Energy Technology Data Exchange (ETDEWEB)

Liu, Yen, E-mail: yen.liu@nasa.gov; Vinokur, Marcel [NASA Ames Research Center, Moffett Field, California 94035 (United States); Panesi, Marco; Sahai, Amal [University of Illinois, Urbana-Champaign, Illinois 61801 (United States)

2015-04-07

relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

Science.gov (United States)

Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

2015-04-01

relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.

Science.gov (United States)

Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

2015-04-07

relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

International Nuclear Information System (INIS)

Liu, Yen; Vinokur, Marcel; Panesi, Marco; Sahai, Amal

2015-01-01

relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations

Quantitative analysis of the near-wall mixture formation process in a passenger car direct-injection diesel engine by using linear raman spectroscopy.

Science.gov (United States)

Taschek, Marco; Egermann, Jan; Schwarz, Sabrina; Leipertz, Alfred

2005-11-01

Optimum fuel preparation and mixture formation are core issues in the development of modern direct-injection (DI) Diesel engines, as these are crucial for defining the border conditions for the subsequent combustion and pollutant formation process. The local fuel/air ratio can be seen as one of the key parameters for this optimization process, as it allows the characterization and comparison of the mixture formation quality. For what is the first time to the best of our knowledge, linear Raman spectroscopy is used to detect the fuel/air ratio and its change along a line of a few millimeters directly and nonintrusively inside the combustion bowl of a DI Diesel engine. By a careful optimization of the measurement setup, the weak Raman signals could be separated successfully from disturbing interferences. A simultaneous measurement of the densities of air and fuel was possible along a line of about 10 mm length, allowing a time- and space-resolved measurement of the local fuel/air ratio. This could be performed in a nonreacting atmosphere as well as during fired operating conditions. The positioning of the measurement volume next to the interaction point of one of the spray jets with the wall of the combustion bowl allowed a near-wall analysis of the mixture formation process for a six-hole nozzle under varying injection and engine conditions. The results clearly show the influence of the nozzle geometry and preinjection on the mixing process. In contrast, modulation of the intake air temperature merely led to minor changes of the fuel concentration in the measurement volume.

Mixtures of Berkson and classical covariate measurement error in the linear mixed model: Bias analysis and application to a study on ultrafine particles.

Science.gov (United States)

Deffner, Veronika; Küchenhoff, Helmut; Breitner, Susanne; Schneider, Alexandra; Cyrys, Josef; Peters, Annette

2018-03-13

The ultrafine particle measurements in the Augsburger Umweltstudie, a panel study conducted in Augsburg, Germany, exhibit measurement error from various sources. Measurements of mobile devices show classical possibly individual-specific measurement error; Berkson-type error, which may also vary individually, occurs, if measurements of fixed monitoring stations are used. The combination of fixed site and individual exposure measurements results in a mixture of the two error types. We extended existing bias analysis approaches to linear mixed models with a complex error structure including individual-specific error components, autocorrelated errors, and a mixture of classical and Berkson error. Theoretical considerations and simulation results show, that autocorrelation may severely change the attenuation of the effect estimations. Furthermore, unbalanced designs and the inclusion of confounding variables influence the degree of attenuation. Bias correction with the method of moments using data with mixture measurement error partially yielded better results compared to the usage of incomplete data with classical error. Confidence intervals (CIs) based on the delta method achieved better coverage probabilities than those based on Bootstrap samples. Moreover, we present the application of these new methods to heart rate measurements within the Augsburger Umweltstudie: the corrected effect estimates were slightly higher than their naive equivalents. The substantial measurement error of ultrafine particle measurements has little impact on the results. The developed methodology is generally applicable to longitudinal data with measurement error. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data].

Science.gov (United States)

Yan, En-ping; Lin, Hui; Wang, Guang-xing; Chen, Zhen-xiong

2015-11-01

With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian co-simulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t · hm(-2), ranging from 0.00 to 67.35 t · hm(-2). This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.

Studies on Molecular Interaction in Ternary Liquid Mixtures

Directory of Open Access Journals (Sweden)

R. Uvarani

2010-01-01

Full Text Available Ultrasonic velocity, density and viscosity for the ternary liquid mixtures of cyclohexanone with 1-propanol and 1-butanol in carbon tetrachloride were measured at 303 K. The acoustical parameters and their excess values were calculated. The trends in the variation of these excess parameters were used to discuss the nature and strength of the interactions present between the component molecules.

Linear optical response of finite systems using multishift linear system solvers

Energy Technology Data Exchange (ETDEWEB)

Hübener, Hannes; Giustino, Feliciano [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)

2014-07-28

We discuss the application of multishift linear system solvers to linear-response time-dependent density functional theory. Using this technique the complete frequency-dependent electronic density response of finite systems to an external perturbation can be calculated at the cost of a single solution of a linear system via conjugate gradients. We show that multishift time-dependent density functional theory yields excitation energies and oscillator strengths in perfect agreement with the standard diagonalization of the response matrix (Casida's method), while being computationally advantageous. We present test calculations for benzene, porphin, and chlorophyll molecules. We argue that multishift solvers may find broad applicability in the context of excited-state calculations within density-functional theory and beyond.

Muon cycling rate in D/T mixture including doubly muonic molecule formation

Directory of Open Access Journals (Sweden)

M. R. Eskandari

2002-06-01

Full Text Available   In the present work, the fundamental behavior of four body molecule formations of pt μμ , pd μμ , dt μμ , tt μμ , and pp μμ in a D/T fusion are considered. Their higher fusion rate, specially the available data for dt μμ , encouraged us to study the muon cycling rate in D/T fusion in the temperature range of (100-1400 K, density and deuterium-tritium concentration ratio. For this purpose, various values for the doubly muonic molecule formation are chosen and with the comparison to the experimental results, the doubly muonic formation rate of 109 s-1 is predicted theoretically. Our calculated cycling rate has shown that having not considered the doubly muonic formation in previous calculations had made no serious changes in the previously calculated values.

Viscous properties of isotropic fluids composed of linear molecules: departure from the classical Navier-Stokes theory in nano-confined geometries.

Science.gov (United States)

Hansen, J S; Daivis, Peter J; Todd, B D

2009-10-01

In this paper we present equilibrium molecular-dynamics results for the shear, rotational, and spin viscosities for fluids composed of linear molecules. The density dependence of the shear viscosity follows a stretched exponential function, whereas the rotational viscosity and the spin viscosities show approximately power-law dependencies. The frequency-dependent shear and spin viscosities are also studied. It is found that viscoelastic behavior is first manifested in the shear viscosity and that the real part of the spin viscosities features a maximum for nonzero frequency. The calculated transport coefficients are used together with the extended Navier-Stokes equations to investigate the effect of the coupling between the intrinsic angular momentum and linear momentum for highly confined fluids. Both steady and oscillatory flows are studied. It is shown, for example, that the fluid flow rate for Poiseuille flow is reduced by up to 10% in a 2 nm channel for a buta-triene fluid at density 236 kg m(-3) and temperature 306 K. The coupling effect may, therefore, become very important for nanofluidic applications.

Xanthine-Catechin Mixture Enhances Lithium-Induced Anti-Inflammatory Response in Activated Macrophages In Vitro

Directory of Open Access Journals (Sweden)

Fernanda Barbisan

2017-01-01

Full Text Available Lithium (Li is a chemical element used for treating and preventing bipolar disorder (BD and exerts positive effects such as anti-inflammatory effects as well as undesirable side effects. These effects of Li can be influenced by interaction with some nutritional elements. Therefore, we investigated the potential effects of xanthine (caffeine and theobromine and catechin molecules present in some food beverages broadly consumed worldwide, such as coffee and tea, on Li-induced anti-inflammatory effects. In the present study, we concomitantly exposed RAW 264.7 macrophages to Li, isolated xanthine and catechin molecules, and a xanthine-catechin mixture (XC mixture. We evaluated the effects of these treatments on cell proliferation, cell cycle progression, oxidative and antioxidant marker expression, cytokine levels, gene expression, and GSK-3β enzyme expression. Treatment with the XC mixture potentialized Li-induced anti-inflammatory effects by intensification of the following: GSK-3β inhibitory action, lowering effect on proinflammatory cytokines (IL-1β, IL-6, and TNFα, and increase in the levels of IL-10 that is an anti-inflammatory cytokine. Despite the controversial nature of caffeine consumption by BD patients, these results suggested that consumption of caffeine, in low concentrations, mixed with other bioactive molecules along with Li may be safe.

Full Alignment of Molecules Using Elliptically Polarized Light

DEFF Research Database (Denmark)

Larsen, Jakob Juul; Hald, Kasper; Seideman, Tamar

When a molecule with an anisotropic polarizability is placed in a strong nonresonant laser field the interaction occurs through the induced dipole moment. The outcome is that the molecule experiences an angular dependent potential energy. It is now well established that a linearly polarized laser...... field can be used to align molecules along their axis of highest polarizability. Here we demonstrate, theoretically and experimentally, that an elliptically polarized laser field can be used to simultaneously force two axes of a molecule into alignment through the same mechanism. Due to the rigidity...

Study of intermolecular interactions in binary mixtures of ethanol in methanol

Science.gov (United States)

Maharolkar, Aruna P.; Khirade, P. W.; Murugkar, A. G.

2016-05-01

Present paper deals with study of physicochemical properties like viscosity, density and refractive index for the binary mixtures of ethanol and methanol over the entire concentration range were measured at 298.15 K. The experimental data further used to determine the excess properties viz. excess molar volume, excess viscosity, excess molar refraction. The values of excess properties further fitted with Redlich-Kister (R-K Fit) equation to calculate the binary coefficients and standard deviation. The resulting excess parameters are used to indicate the presence of intermolecular interactions and strength of intermolecular interactions between the molecules in the binary mixtures. Excess parameters indicate structure making factor in the mixture predominates in the system.

The Maxwell-Stefan description of mixture diffusion in nanoporous crystalline materials

NARCIS (Netherlands)

Krishna, R.

2014-01-01

The efficacy of nanoporous crystalline materials in separation applications is often influenced to a significant extent by diffusion of guest molecules within the pores of the structural frameworks. The Maxwell-Stefan (M-S) equations provide a fundamental and convenient description of mixture

Structural and energetic properties of La3+ in water/DMSO mixtures

Science.gov (United States)

Montagna, Maria; Spezia, Riccardo; Bodo, Enrico

2017-11-01

By using molecular dynamics based on a custom polarizable force field, we have studied the solvation of La3+ in an equimolar mixture of dimethylsulfoxide (DMSO) with water. An extended structural analysis has been performed to provide a complete picture of the physical properties at the basis of the interaction of La3+ with both solvents. Through our simulations we found that, very likely, the first solvation shell in the mixture is not unlike the one found in pure water or pure DMSO and contains 9 solvent molecules. We have also found that the solvation is preferentially due to DMSO molecules with the water initially present in first shell quickly leaving to the bulk. The dehydration process of the first shell has been analyzed by both plain MD simulations and a constrained dynamics approach; the free energy profiles for the extraction of water from first shell have also been computed.

Sol-gel method for encapsulating molecules

Science.gov (United States)

Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

2002-01-01

A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

Suppression and enhancement of non-native molecules within biological systems

Energy Technology Data Exchange (ETDEWEB)

Jones, E.A. [Surface Analysis Research Centre, CEAS, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom)]. E-mail: e.jones@postgrad.manchester.ac.uk; Lockyer, N.P. [Surface Analysis Research Centre, CEAS, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom); Vickerman, J.C. [Surface Analysis Research Centre, CEAS, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom)

2006-07-30

With the aim of evaluating the potential of SIMS to provide molecular information from small molecules within biological systems, here we investigate the effect of different biological compounds as they act as matrices. The results highlight the fact that the chemical environment of a molecule can have a significant effect on its limit of detection. This has implications for the imaging of drugs and xenobiotics in tissue sections and other biological matrices. A 1:1 mixture of the organic acid 2,4,6-trihydroxyacetophenone and the dipeptide valine-valine demonstrates that almost complete suppression of the [M + H]{sup +} ion of one compound can be caused by the presence of a compound of higher proton affinity. The significance of this is highlighted when two similar drug molecules, atropine (a neutral molecule) and ipratropium bromide (a quaternary nitrogen containing salt) are mixed with brain homogenate. The atropine [M + H]{sup +} ion shows significant suppression whilst the [M - Br]{sup +} of ipratopium bromide is detected at an intensity that can be rationalised by its decreased surface concentration. By investigating the effect of two abundant tissue lipids, cholesterol and dipalmitoylphosphatidyl choline (DPPC), on the atropine [M + H]{sup +} signal detected in mixtures with these lipids we see that the DPPC has a strong suppressing effect, which may be attributed to gas phase proton transfer.

Phase space structure of triatomic molecules

International Nuclear Information System (INIS)

Lu, Z.; Kellman, M.E.

1997-01-01

The bifurcation structure is investigated for a Hamiltonian for the three coupled nonlinear vibrations of a highly excited triatomic molecule. The starting point is a quantum Hamiltonian used to fit experimental spectra. This Hamiltonian includes 1:1 Darling endash Dennison resonance coupling between the stretches, and 2:1 Fermi resonance coupling between the stretches and bend. A classical Hamiltonian is obtained using the Heisenberg correspondence principle. Surfaces of section show a pronounced degree of chaos at high energies, with a mixture of chaotic and regular dynamics. The large-scale bifurcation structure is found semianalytically, without recourse to numerical solution of Hamilton close-quote s equations, by taking advantage of the fact that the spectroscopic Hamiltonian has a conserved polyad quantum number, corresponding to an approximate constant of the motion of the molecule. Bifurcation diagrams are analyzed for a number of molecules including H 2 O, D 2 O, NO 2 , ClO 2 , O 3 , and H 2 S. copyright 1997 American Institute of Physics

Separation of a multicomponent mixture by gaseous diffusion: modelization of the enrichment in a capillary - application to a pilot cascade

International Nuclear Information System (INIS)

Doneddu, F.

1982-01-01

Starting from the modelization of gaseous flow in a porous medium (flow in a capillary), we generalize the law of enrichment in an infinite cylindrical capillary, established for an isotropic linear mixture, to a multicomponent mixture. A generalization is given of the notion of separation yields and characteristic pressure classically used for separations of isotropic linear mixtures. We present formulas for diagonalizing the diffusion operator, modelization of a multistage, gaseous diffusion cascade and comparison with the experimental results of a drain cascade (N 2 -SF 6 -UF 6 mixture). [fr

Validated HPTLC methods for determination of some selected antihypertensive mixtures in their combined dosage forms

Directory of Open Access Journals (Sweden)

Rasha A. Shaalan

2014-12-01

Full Text Available Simple and selective HPTLC methods were developed for the simultaneous determination of the antihypertensive drugs; carvedilol and hydrochlorothiazide in their binary mixture (Mixture I and amlodipine besylate, valsartan, and hydrochlorothiazide in their combined ternary formulation (Mixture II. Effective chromatographic separation was achieved on Fluka TLC plates 20 × 20 cm aluminum cards, 0.2 mm thickness through linear ascending development. For Mixture I, the mobile phase composed of chloroform–methanol in the ratio 8:2 v/v. Detection was performed at 254 nm for both carvedilol and hydrochlorothiazide. For Mixture II, the mobile phase was chloroform–methanol–ammonia in the volume ratio 8:2:0.1. Detection was performed at 254 nm for valsartan and hydrochlorothiazide, and at 365 nm for amlodipine. Quantification was based on spectrodensitometric analysis. Analytical performance of the proposed HPTLC procedures was statistically validated with respect to linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. The linearity ranges were 0.05–1.0 and 0.1–2.0 μg/spot for carvedilol and hydrochlorothiazide, respectively in Mixture I, 0.1–2.0, 0.1–2.0 and 0.2–4.0 μg/spot for amlodipine, hydrochlorothiazide and valsartan, respectively in Mixture II, with correlation coefficients >0.9992. The validated HPTLC methods were applied to the analysis of the cited antihypertensive drugs in their combined pharmaceutical tablets. The proposed methods confirmed peak identity and purity.

Overlapping effects during the fermentation of substrate mixtures; Ueberlagerungseffekte bei der Vergaerung von Substratmischungen

Energy Technology Data Exchange (ETDEWEB)

Engler, Nils; Nelles, Michael [Rostock Univ. (Germany). Lehrstuhl fuer Abfall- und Stoffstromwirtschaft

2013-10-01

Co-digestion of different feedstock for biogas plants has been studied comprehensively in the last decades. It can be assumed that the biogas yield as well as the methane yield of substrate mixtures can be calculated by linear superposition of the single component's yields. Influence of substrate mixture on kinetics of biogas formation however was hardly studied. In the experiments described below, single substrates as well as mixtures of them were tested by means of a method developed in previous projects. This method allows to measure biogas formation at high temporal resolution. The influence of inoculum sludge was studied in a second experimental run. According to the results it can be assumed that not only the biogas yield, but also the kinetics of biogas formation from substrate mixtures can be calculated by linear superposition of the kinetics of the single components. (orig.)

Aligning molecules with intense nonresonant laser fields

DEFF Research Database (Denmark)

Larsen, J.J.; Safvan, C.P.; Sakai, H.

1999-01-01

Molecules in a seeded supersonic beam are aligned by the interaction between an intense nonresonant linearly polarized laser field and the molecular polarizability. We demonstrate the general applicability of the scheme by aligning I2, ICl, CS2, CH3I, and C6H5I molecules. The alignment is probed...... by mass selective two dimensional imaging of the photofragment ions produced by femtosecond laser pulses. Calculations on the degree of alignment of I2 are in good agreement with the experiments. We discuss some future applications of laser aligned molecules....

Measuring two-phase and two-component mixtures by radiometric technique

International Nuclear Information System (INIS)

Mackuliak, D.; Rajniak, I.

1984-01-01

The possibility was tried of the application of the radiometric method in measuring steam water content. The experiments were carried out in model conditions where steam was replaced with the two-component mixture of water and air. The beta radiation source was isotope 204 Tl (Esub(max)=0.765 MeV) with an activity of 19.35 MBq. Measurements were carried out within the range of the surface density of the mixture from 0.119 kg.m -2 to 0.130 kg.m -2 . Mixture speed was 5.1 m.s -1 to 7.1 m.s -1 . The observed dependence of relative pulse frequency on the specific water content in the mixture was approximated by a linear regression. (B.S.)

A Simple Refraction Experiment for Probing Diffusion in Ternary Mixtures

Science.gov (United States)

Coutinho, Cecil A.; Mankidy, Bijith D.; Gupta, Vinay K.

2010-01-01

Diffusion is a fundamental phenomenon that is vital in many chemical processes such as mass transport in living cells, corrosion, and separations. We describe a simple undergraduate-level experiment based on Weiner's Method to probe diffusion in a ternary aqueous mixture of small molecular-weight molecules. As an illustration, the experiment…

A simulated Linear Mixture Model to Improve Classification Accuracy of Satellite Data Utilizing Degradation of Atmospheric Effect

Directory of Open Access Journals (Sweden)

WIDAD Elmahboub

2005-02-01

Full Text Available Researchers in remote sensing have attempted to increase the accuracy of land cover information extracted from remotely sensed imagery. Factors that influence the supervised and unsupervised classification accuracy are the presence of atmospheric effect and mixed pixel information. A linear mixture simulated model experiment is generated to simulate real world data with known end member spectral sets and class cover proportions (CCP. The CCP were initially generated by a random number generator and normalized to make the sum of the class proportions equal to 1.0 using MATLAB program. Random noise was intentionally added to pixel values using different combinations of noise levels to simulate a real world data set. The atmospheric scattering error is computed for each pixel value for three generated images with SPOT data. Accuracy can either be classified or misclassified. Results portrayed great improvement in classified accuracy, for example, in image 1, misclassified pixels due to atmospheric noise is 41 %. Subsequent to the degradation of atmospheric effect, the misclassified pixels were reduced to 4 %. We can conclude that accuracy of classification can be improved by degradation of atmospheric noise.

Efficient production of long-lived ultracold Sr2 molecules

Science.gov (United States)

Ciamei, Alessio; Bayerle, Alex; Chen, Chun-Chia; Pasquiou, Benjamin; Schreck, Florian

2017-07-01

We associate Sr atom pairs on sites of a Mott insulator optically and coherently into weakly bound ground-state molecules, achieving an efficiency above 80%. This efficiency is 2.5 times higher than in our previous work [S. Stellmer, B. Pasquiou, R. Grimm, and F. Schreck, Phys. Rev. Lett. 109, 115302 (2012), 10.1103/PhysRevLett.109.115302] and obtained through two improvements. First, the lifetime of the molecules is increased beyond one minute by using an optical lattice wavelength that is further detuned from molecular transitions. Second, we compensate undesired dynamic light shifts that occur during the stimulated Raman adiabatic passage (STIRAP) used for molecule association. We also characterize and model STIRAP, providing insights into its limitations. Our work shows that significant molecule association efficiencies can be achieved even for atomic species or mixtures that lack Feshbach resonances suitable for magnetoassociation.

Stepped MS(All) Relied Transition (SMART): An approach to rapidly determine optimal multiple reaction monitoring mass spectrometry parameters for small molecules.

Science.gov (United States)

Ye, Hui; Zhu, Lin; Wang, Lin; Liu, Huiying; Zhang, Jun; Wu, Mengqiu; Wang, Guangji; Hao, Haiping

2016-02-11

Multiple reaction monitoring (MRM) is a universal approach for quantitative analysis because of its high specificity and sensitivity. Nevertheless, optimization of MRM parameters remains as a time and labor-intensive task particularly in multiplexed quantitative analysis of small molecules in complex mixtures. In this study, we have developed an approach named Stepped MS(All) Relied Transition (SMART) to predict the optimal MRM parameters of small molecules. SMART requires firstly a rapid and high-throughput analysis of samples using a Stepped MS(All) technique (sMS(All)) on a Q-TOF, which consists of serial MS(All) events acquired from low CE to gradually stepped-up CE values in a cycle. The optimal CE values can then be determined by comparing the extracted ion chromatograms for the ion pairs of interest among serial scans. The SMART-predicted parameters were found to agree well with the parameters optimized on a triple quadrupole from the same vendor using a mixture of standards. The parameters optimized on a triple quadrupole from a different vendor was also employed for comparison, and found to be linearly correlated with the SMART-predicted parameters, suggesting the potential applications of the SMART approach among different instrumental platforms. This approach was further validated by applying to simultaneous quantification of 31 herbal components in the plasma of rats treated with a herbal prescription. Because the sMS(All) acquisition can be accomplished in a single run for multiple components independent of standards, the SMART approach are expected to find its wide application in the multiplexed quantitative analysis of complex mixtures. Copyright © 2015 Elsevier B.V. All rights reserved.

Linear ubiquitination signals in adaptive immune responses.

Science.gov (United States)

Ikeda, Fumiyo

2015-07-01

Ubiquitin can form eight different linkage types of chains using the intrinsic Met 1 residue or one of the seven intrinsic Lys residues. Each linkage type of ubiquitin chain has a distinct three-dimensional topology, functioning as a tag to attract specific signaling molecules, which are so-called ubiquitin readers, and regulates various biological functions. Ubiquitin chains linked via Met 1 in a head-to-tail manner are called linear ubiquitin chains. Linear ubiquitination plays an important role in the regulation of cellular signaling, including the best-characterized tumor necrosis factor (TNF)-induced canonical nuclear factor-κB (NF-κB) pathway. Linear ubiquitin chains are specifically generated by an E3 ligase complex called the linear ubiquitin chain assembly complex (LUBAC) and hydrolyzed by a deubiquitinase (DUB) called ovarian tumor (OTU) DUB with linear linkage specificity (OTULIN). LUBAC linearly ubiquitinates critical molecules in the TNF pathway, such as NEMO and RIPK1. The linear ubiquitin chains are then recognized by the ubiquitin readers, including NEMO, which control the TNF pathway. Accumulating evidence indicates an importance of the LUBAC complex in the regulation of apoptosis, development, and inflammation in mice. In this article, I focus on the role of linear ubiquitin chains in adaptive immune responses with an emphasis on the TNF-induced signaling pathways. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Solution thermodynamics and preferential solvation of sulfamethazine in (methanol + water) mixtures

International Nuclear Information System (INIS)

Delgado, Daniel R.; Almanza, Ovidio A.; Martínez, Fleming; Peña, María A.; Jouyban, Abolghasem; Acree, William E.

2016-01-01

Highlights: • Solubility of sulfamethazine (SMT) was measured in (methanol + water) mixtures. • SMT solubility was correlated with Jouyban–Acree model. • Gibbs energy, enthalpy, and entropy of dissolution of SMT were calculated. • Non-linear enthalpy–entropy relationship was observed for SMT. • Preferential solvation of SMT by methanol was analyzed by using the IKBI method. - Abstract: The solubility of sulfamethazine (SMT) in {methanol (1) + water (2)} co-solvent mixtures was determined at five different temperatures from (293.15 to 313.15) K. The sulfonamide exhibited its highest mole fraction solubility in pure methanol (δ 1 = 29.6 MPa 1/2 ) and its lowest mole fraction solubility in water (δ 2 = 47.8 MPa 1/2 ) at each of the five temperatures studied. The Jouyban–Acree model was used to correlate/predict the solubility values. The respective apparent thermodynamic functions Gibbs energy, enthalpy, and entropy of solution were obtained from the solubility data through the van’t Hoff and Gibbs equations. Apparent thermodynamic quantities of mixing were also calculated for this drug using values of the ideal solubility reported in the literature. A non-linear enthalpy–entropy relationship was noted for SMT in plots of both the enthalpy vs. Gibbs energy of mixing and the enthalpy vs. entropy of mixing. These plots suggest two different trends according to the slopes obtained when the composition of the mixtures changes. Accordingly, the mechanism for SMT transfer processes in water-rich mixtures from water to the mixture with 0.70 in mass fraction of methanol is entropy driven. Conversely, the mechanism is enthalpy driven in mixtures whenever the methanol composition exceeds 0.70 mol fraction. An inverse Kirkwood–Buff integral analysis of the preferential solvation of SMT indicated that the drug is preferentially solvated by water in water-rich mixtures but is preferentially solvated by methanol in methanol-rich mixtures.

Theoretical studies on nuclear spin selective quantum dynamics of non-linear molecules; Theoretische Untersuchung zur Quantendynamik der Kernspinisomere nicht-linearer Molekuele

Energy Technology Data Exchange (ETDEWEB)

Grohmann, Thomas

2012-05-31

In this thesis the wave packet dynamics of nuclear spin isomers of polyatomic molecules after interaction with static and time-dependent magnetic fields and moderate intense nonresonant laser pulses is investigated. In particular, the process of inducing (internal) molecular rotation as well as alignment of molecules by manipulating their rotational or rotational-torsional degrees of freedom is studied. In the first part of the thesis all theoretical concepts for identifying nuclear spin isomers and for describing their quantum dynamics will be discussed. Especially the symmetrization postulate and themolecular symmetry group will be introduced and illustrated for some examples of molecules. These concepts will be extended to the case of identifying nuclear spin isomers in the presence of an external field. In the second part it is shown for nitromethane that magnetic fields are able to induce unidirectional rotations in opposite directions for different nuclear spin isomers of molecules containing methyl groups if the dipolar interaction is included. Additionally, it is demonstrated that different nuclear spin isomers of a chemical compound may show different alignment after the interaction with a moderate intense laser pulse. As shown for the rigid symmetric top propadien and the rigid asymmetric tops ethene and analogues, distinct pairs of nuclear spin isomers show at certain points in time a complementary behavior: while one isomer is showing alignment the partner isomer is showing anti-alignment. Moreover, it is illustrated that not every nuclear spin isomer can be aligned equally efficient. The alignment of non-rigid molecules is considered as well. As an example for a molecule with feasible torsion in the electronic ground state, the alignment of diboron tetrafluoride is investigated. It becomes apparent that not only rotational but also the torsional dynamics of the molecules is nuclear spin selective; different nuclear spin isomers have at distinct points

Responsive gelation of hydrophobized linear polymer

DEFF Research Database (Denmark)

Madsen, Claus Greve; Toeth, Joachim; Jørgensen, Lene

In this study we present the rheological properties of a physically linked polymer network, composed of linear hydrophilic chains, modified with hydrophobic moieties in each end. Solutions of the polymer in ethanol-water mixtures showed Newtonian behaviour up to about 99 % ethanol, with the highest...

Glass polymorphism in glycerol-water mixtures: I. A computer simulation study.

Science.gov (United States)

Jahn, David A; Wong, Jessina; Bachler, Johannes; Loerting, Thomas; Giovambattista, Nicolas

2016-04-28

We perform out-of-equilibrium molecular dynamics (MD) simulations of water-glycerol mixtures in the glass state. Specifically, we study the transformations between low-density (LDA) and high-density amorphous (HDA) forms of these mixtures induced by compression/decompression at constant temperature. Our MD simulations reproduce qualitatively the density changes observed in experiments. Specifically, the LDA-HDA transformation becomes (i) smoother and (ii) the hysteresis in a compression/decompression cycle decreases as T and/or glycerol content increase. This is surprising given the fast compression/decompression rates (relative to experiments) accessible in MD simulations. We study mixtures with glycerol molar concentration χ(g) = 0-13% and find that, for the present mixture models and rates, the LDA-HDA transformation is detectable up to χ(g) ≈ 5%. As the concentration increases, the density of the starting glass (i.e., LDA at approximately χ(g) ≤ 5%) rapidly increases while, instead, the density of HDA remains practically constant. Accordingly, the LDA state and hence glass polymorphism become inaccessible for glassy mixtures with approximately χ(g) > 5%. We present an analysis of the molecular-level changes underlying the LDA-HDA transformation. As observed in pure glassy water, during the LDA-to-HDA transformation, water molecules within the mixture approach each other, moving from the second to the first hydration shell and filling the first interstitial shell of water molecules. Interestingly, similar changes also occur around glycerol OH groups. It follows that glycerol OH groups contribute to the density increase during the LDA-HDA transformation. An analysis of the hydrogen bond (HB)-network of the mixtures shows that the LDA-HDA transformation is accompanied by minor changes in the number of HBs of water and glycerol. Instead, large changes in glycerol and water coordination numbers occur. We also perform a detailed analysis of the effects that

The Role of Molecule Clustering by Hydrogen Bond in Hydrous Ethanol on Laminar Burning Velocity

Directory of Open Access Journals (Sweden)

I Made Suarta

2016-01-01

Full Text Available The role of hydrogen bond molecule clustering in laminar burning velocities was observed. The water in hydrous ethanol can change the interaction between water-ethanol molecules. A certain amount of water can become oxygenated which increases the burning velocity. The hydrogen bond interaction pattern of ethanol and water molecules was modeled. Based on the molecular model, azeotropic behavior emerges from ethanol-water hydrogen bond, which is at a 95.1%v composition. The interaction with water molecule causes the ethanol molecule to be clustered with centered oxygenated compound. So, it supplies extra oxygen and provides intermolecular empty spaces that are easily infiltrated by the air. In the azeotropic composition, the molecular bond chain is the shortest, so hypothetically the burning velocity is anticipated to increase. The laminar burning velocity of ethanol fuel was tested in a cylindrical explosion bomb in lean, stoichiometric, and rich mixtures. The experimental result showed that the maximum burning velocity occurred at hydrous ethanol of 95.5%v composition. This discrepancy is the result of the addition of energy from 7.7% free ethanol molecules that are not clustered. At the rich mixture, the burning velocity of this composition is higher than that of anhydrous ethanol.

Soot modeling of counterflow diffusion flames of ethylene-based binary mixture fuels

KAUST Repository

Wang, Yu; Raj, Abhijeet Dhayal; Chung, Suk-Ho

2015-01-01

of ethylene and its binary mixtures with methane, ethane and propane based on the method of moments. The soot model has 36 soot nucleation reactions from 8 PAH molecules including pyrene and larger PAHs. Soot surface growth reactions were based on a modified

Mixture-mixture design for the fingerprint optimization of chromatographic mobile phases and extraction solutions for Camellia sinensis.

Science.gov (United States)

Borges, Cleber N; Bruns, Roy E; Almeida, Aline A; Scarminio, Ieda S

2007-07-09

A composite simplex centroid-simplex centroid mixture design is proposed for simultaneously optimizing two mixture systems. The complementary model is formed by multiplying special cubic models for the two systems. The design was applied to the simultaneous optimization of both mobile phase chromatographic mixtures and extraction mixtures for the Camellia sinensis Chinese tea plant. The extraction mixtures investigated contained varying proportions of ethyl acetate, ethanol and dichloromethane while the mobile phase was made up of varying proportions of methanol, acetonitrile and a methanol-acetonitrile-water (MAW) 15%:15%:70% mixture. The experiments were block randomized corresponding to a split-plot error structure to minimize laboratory work and reduce environmental impact. Coefficients of an initial saturated model were obtained using Scheffe-type equations. A cumulative probability graph was used to determine an approximate reduced model. The split-plot error structure was then introduced into the reduced model by applying generalized least square equations with variance components calculated using the restricted maximum likelihood approach. A model was developed to calculate the number of peaks observed with the chromatographic detector at 210 nm. A 20-term model contained essentially all the statistical information of the initial model and had a root mean square calibration error of 1.38. The model was used to predict the number of peaks eluted in chromatograms obtained from extraction solutions that correspond to axial points of the simplex centroid design. The significant model coefficients are interpreted in terms of interacting linear, quadratic and cubic effects of the mobile phase and extraction solution components.

Emission characteristics of plasma based on xenon-rubidium bromide mixture

Science.gov (United States)

Heneral, A. A.; Avtaeva, S. V.

2017-10-01

Luminescence spectra of a longitudinal pulse-periodic discharge in xenon mixture with rubidium bromide vapors (Xe-RbBr) are studied experimentally at low pressures. The conditions leading to the appearance of intense bands of ultraviolet radiation of exciplex XeBr* molecules in the spectral interval between 200 and 400 nm are found. The highest yield of UV radiation of XeBr* molecules is achieved when the temperature of discharge-tube walls is equal to 750°C. A maximum power of UV radiation from the entire plasma volume as high as 4.8 W is obtained.

Generalization of the linear algebraic method to three dimensions

International Nuclear Information System (INIS)

Lynch, D.L.; Schneider, B.I.

1991-01-01

We present a numerical method for the solution of the Lippmann-Schwinger equation for electron-molecule collisions. By performing a three-dimensional numerical quadrature, this approach avoids both a basis-set representation of the wave function and a partial-wave expansion of the scattering potential. The resulting linear equations, analogous in form to the one-dimensional linear algebraic method, are solved with the direct iteration-variation method. Several numerical examples are presented. The prospect for using this numerical quadrature scheme for electron-polyatomic molecules is discussed

Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets

DEFF Research Database (Denmark)

Pentlehner, Dominik; H. Nielsen, Jens; Slenczka, Alkwin

2013-01-01

We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules...

Mechanical response of collagen molecule under hydrostatic compression

International Nuclear Information System (INIS)

Saini, Karanvir; Kumar, Navin

2015-01-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials.

Mechanical response of collagen molecule under hydrostatic compression.

Science.gov (United States)

Saini, Karanvir; Kumar, Navin

2015-04-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials. Copyright © 2015 Elsevier B.V. All rights

Mechanical response of collagen molecule under hydrostatic compression

Energy Technology Data Exchange (ETDEWEB)

Saini, Karanvir, E-mail: karans@iitrpr.ac.in; Kumar, Navin

2015-04-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials.

Cold guided beams of polar molecules

International Nuclear Information System (INIS)

Motsch, Michael

2010-01-01

This thesis reports on experiments characterizing cold guided beams of polar molecules which are produced by electrostatic velocity filtering. This filtering method exploits the interaction between the polar molecules and the electric field provided by an electrostatic quadrupole guide to extract efficiently the slow molecules from a thermal reservoir. For molecules with large and linear Stark shifts such as deuterated ammonia (ND 3 ) or formaldehyde (H 2 CO), fluxes of guided molecules of 10 10 -10 11 molecules/s are produced. The velocities of the molecules in these beams are in the range of 10-200 m/s and correspond to typical translational temperatures of a few Kelvin. The maximum velocity of the guided molecules depends on the Stark shift, the molecular mass, the geometry of the guide, and the applied electrode voltage. Although the source is operated in the near-effusive regime, the number density of the slowest molecules is sensitive to collisions. A theoretical model, taking into account this velocity-dependent collisional loss of molecules in the vicinity of the nozzle, reproduces the density of the guided molecules over a wide pressure range. A careful adjustment of pressure allows an increase in the total number of molecules, whilst yet minimizing losses due to collisions of the sought-for slow molecules. This is an important issue for future applications. Electrostatic velocity filtering is suited for different molecular species. This is demonstrated by producing cold guided beams of the water isotopologs H 2 O, D 2 O, and HDO. Although these are chemically similar, they show linear and quadratic Stark shifts, respectively, when exposed to external electric fields. As a result, the flux of HDO is larger by one order of magnitude, and the flux of the individual isotopologs shows a characteristic dependence on the guiding electric field. The internal-state distribution of guided molecules is studied with a newly developed diagnostic method: depletion

Theoretical study of molecular vibration and Application to linear triatomic molecules: case of OCS

International Nuclear Information System (INIS)

Andrianavalomahefa, A.

2014-01-01

Our aim is to give a theoretical approach to the calculation of vibrational energy levels of polyatomic molecules. By using matrix calculation, we have to solve an eigenvalue equation that gives normal vibration frequencies of the system. A basis change introduces normal coordinates of vibration, which diagonalize the Hamiltonian. The harmonic approximation gives a rough evaluation of parameters which describe the system. Then, we introduce nonlinear terms to take into account the anharmonicity of interatomic bounds. Morse oscillator gives good approximation for diatomic molecules. We consider cubic and quartic potential terms for polyatomic molecules. We treat the problem both in classical and quantum approach. The results thus obtained are applied to study longitudinal vibration of carbonyl sulfide. [fr

Solution Thermodynamics of Lysine Clonixinate in Some Ethanol + Water Mixtures

OpenAIRE

Delgado, Daniel R.; Martínez, Fleming; Gutiérrez, Rahumir A.

2012-01-01

The solubility of lysine clonixinate (LysClon) in several ethanol + water mixtures was determined at 293.15 to 313.15 K. The thermodynamic functions, Gibbs energy, enthalpy, and entropy of solution and of mixing were obtained from these solubility data by using the van’t Hoff and Gibbs equations. In general this drug exhibit good solubility and the greatest value was obtained in the mixture 0.60 in mass fraction of ethanol. A non-linear enthalpy–entropy relationship was observed from ...

Molecular dynamics simulations of tri-n-butyl-phosphate/n-dodecane mixture: thermophysical properties and molecular structure.

Science.gov (United States)

Cui, Shengting; de Almeida, Valmor F; Khomami, Bamin

2014-09-11

Molecular dynamics simulations of tri-n-butyl-phosphate (TBP)/n-dodecane mixture in the liquid phase have been carried out using two recently developed TBP force field models (J. Phys. Chem. B 2012, 116, 305) in combination with the all-atom optimized potentials for liquid simulations (OPLS-AA) force field model for n-dodecane. Specifically, the electric dipole moment of TBP, mass density of the mixture, and the excess volume of mixing were computed with TBP mole fraction ranging from 0 to 1. It is found that the aforementioned force field models accurately predict the mass density of the mixture in the entire mole fraction range. Commensurate with experimental measurements, the electric dipole moment of the TBP was found to slightly increase with the mole fraction of TBP in the mixture. Also, in accord with experimental data, the excess volume of mixing is positive in the entire mole fraction range, peaking at TBP mole fraction range 0.3-0.5. Finally, a close examination of the spatial pair correlation functions between TBP molecules, and between TBP and n-dodecane molecules, revealed formation of TBP dimers through self-association at close distance, a phenomenon with ample experimental evidence.

Self-organising mixture autoregressive model for non-stationary time series modelling.

Science.gov (United States)

Ni, He; Yin, Hujun

2008-12-01

Modelling non-stationary time series has been a difficult task for both parametric and nonparametric methods. One promising solution is to combine the flexibility of nonparametric models with the simplicity of parametric models. In this paper, the self-organising mixture autoregressive (SOMAR) network is adopted as a such mixture model. It breaks time series into underlying segments and at the same time fits local linear regressive models to the clusters of segments. In such a way, a global non-stationary time series is represented by a dynamic set of local linear regressive models. Neural gas is used for a more flexible structure of the mixture model. Furthermore, a new similarity measure has been introduced in the self-organising network to better quantify the similarity of time series segments. The network can be used naturally in modelling and forecasting non-stationary time series. Experiments on artificial, benchmark time series (e.g. Mackey-Glass) and real-world data (e.g. numbers of sunspots and Forex rates) are presented and the results show that the proposed SOMAR network is effective and superior to other similar approaches.

Nanosecond barrier discharge in a krypton/helium mixture containing mercury dibromide: Optical emission and plasma parameters

Science.gov (United States)

Malinina, A. A.; Starikovskaya, S. M.; Malinin, A. N.

2015-01-01

Spectral and electrical characteristics of atmospheric-pressure nanosecond barrier discharge plasma in a HgBr2/Kr/He mixture have been investigated. The discharge was initiated by positive 10-kV voltage pulses with a rise time of 4 ns and a half-amplitude duration of 28 ns. Emission from exciplex HgBr ( B 2Σ{1/2/+} - X 2Σ{1/2/+}) and KrBr ( B 2Σ{1/2/+} - X 2Σ{1/2/+}, C3/2-AΠ1/2, D1/2-AΠ1/2) molecules have been studied. From the time evolution of the B-X transition spectra of the HgBr molecule (502 nm) and KrBr molecule (207 nm), a mechanism of the formation of the exciplex molecules in the nanosecond discharge has been deduced. The distributions of the energies and rates of the processes responsible for emission from HgBr and KrBr molecules have been analyzed by numerically solving the Boltzmann equation for the electron distribution function. Experiments have confirmed the possibility of optimizing the voltage supply pulse for maximizing the efficiency of simultaneous emission in the UV and visible (green) spectral ranges from atmospheric-pressure discharge in the HgBr2/Kr/He mixture.

Before the Ring: synthesis of linear organic molecules in astrophysical ices by low energy electron impact

Science.gov (United States)

Huels, Michael A.; Bass Andrew, D.; Mirsaleh-Kohan, Nasrin; Sanche, Leon

The question of the origin for the building blocks of life, either synthesized here on earth, or in space [1], has been the subject of much debate, experimental investigation, or astronomical observation, much of it stimulated by the early experiments of Miller [2], and subsequent space radiation related variations thereof [3-5]. And while the precise details of the formation of even the simplest biomolecules that make up life on earth still remain shrouded inmystery, one of the notions that persist throughout the debate is that the building blocks of life, such as amino-acids, or even the cyclic components of RNA and DNA, or other cyclic hydrocarbons (e.g. PHAs), where synthesized via radiolysis [6] either in the earths proto-atmosphere, its early oceans, or in the near interstellar space surrounding the early earth. Here we provide experimental evidence for the hypothesis that interactions of low energy secondary electrons and ions, formed during the radiolysis of matter, with atoms and molecules in the medium, may have played, and may still play an important role in the chemical transformation of astrophysical or planetary surface ices [7], where they lead to the synthesis of more complex chemical species from less complex, naturally occurring components. We report the synthesis and desorption of new chemical species from simple molecular surface ices, containing CH4 / CD4 , C2 D2 , O2 , CO, CO2 , or N2 in various combination mixtures, irradiated by low energy (CO+ (n = 1-3), among others. The formation of all these linear, pre-biotic molecular species, produced here by electron initiated cation-reactions in simple molecular films, suggests that similar mechanisms likely precede the synthesis of life's most basic cyclic molecular components in planetary, or astrophysical surface ices that are continuously subjected to the types of space radiations (UV, X-or -ray, or heavy ions) that can generate such low energy secondary electrons. [Funded by NSERC and Canadian

Like-charge attraction and opposite-charge decomplexation between polymers and DNA molecules

OpenAIRE

Buyukdagli, Sahin

2016-01-01

We scrutinize the effect of polyvalent ions on polymer-DNA interactions. We extend a recently developed test charge theory to the case of a stiff polymer interacting with a DNA molecule in an electrolyte mixture. The theory accounts for one-loop level electrostatic correlation effects such as the ionic cloud deformation around the strongly charged DNA molecule as well as image-charge forces induced by the low DNA permittivity. Our model can reproduce and explain various characteristics of the...

Mixtures of bosonic and fermionic atoms in optical lattices

International Nuclear Information System (INIS)

Albus, Alexander; Illuminati, Fabrizio; Eisert, Jens

2003-01-01

We discuss the theory of mixtures of bosonic and fermionic atoms in periodic potentials at zero temperature. We derive a general Bose-Fermi Hubbard Hamiltonian in a one-dimensional optical lattice with a superimposed harmonic trapping potential. We study the conditions for linear stability of the mixture and derive a mean-field criterion for the onset of a bosonic superfluid transition. We investigate the ground-state properties of the mixture in the Gutzwiller formulation of mean-field theory, and present numerical studies of finite systems. The bosonic and fermionic density distributions and the onset of quantum phase transitions to demixing and to a bosonic Mott-insulator are studied as a function of the lattice potential strength. The existence is predicted of a disordered phase for mixtures loaded in very deep lattices. Such a disordered phase possessing many degenerate or quasidegenerate ground states is related to a breaking of the mirror symmetry in the lattice

The underlying toxicological mechanism of chemical mixtures: A case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum

International Nuclear Information System (INIS)

Tian, Dayong; Lin, Zhifen; Zhou, Xianghong; Yin, Daqiang

2013-01-01

Intracellular chemical reaction of chemical mixtures is one of the main reasons that cause synergistic or antagonistic effects. However, it still remains unclear what the influencing factors on the intracellular chemical reaction are, and how they influence on the toxicological mechanism of chemical mixtures. To reveal this underlying toxicological mechanism of chemical mixtures, a case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum was employed, and both their joint effects and mixture toxicity were observed. Then series of two-step linear regressions were performed to describe the relationships between joint effects, the expected additive toxicities and descriptors of individual chemicals (including concentrations, binding affinity to receptors, octanol/water partition coefficients). Based on the quantitative relationships, the underlying joint toxicological mechanisms were revealed. The result shows that, for mixtures with their joint effects resulting from intracellular chemical reaction, their underlying toxicological mechanism depends on not only their interaction with target proteins, but also their transmembrane actions and their concentrations. In addition, two generic points of toxicological mechanism were proposed including the influencing factors on intracellular chemical reaction and the difference of the toxicological mechanism between single reactive chemicals and their mixtures. This study provided an insight into the understanding of the underlying toxicological mechanism for chemical mixtures with intracellular chemical reaction. - Highlights: • Joint effects of nitriles and aldehydes at non-equitoxic ratios were determined. • A novel descriptor, ligand–receptor interaction energy (E binding ), was employed. • Quantitative relationships for mixtures were developed based on a novel descriptor. • The underlying toxic mechanism was revealed based on quantitative relationships. • Two generic

The underlying toxicological mechanism of chemical mixtures: A case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum

Energy Technology Data Exchange (ETDEWEB)

Tian, Dayong [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Department of Chemical and Environmental Engineering, Anyang Institute of Technology, Anyang 455000 (China); Lin, Zhifen, E-mail: lzhifen@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Zhou, Xianghong [Department of Public Management, Tongji University, Shanghai 200092 (China); Yin, Daqiang [Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

2013-10-15

Intracellular chemical reaction of chemical mixtures is one of the main reasons that cause synergistic or antagonistic effects. However, it still remains unclear what the influencing factors on the intracellular chemical reaction are, and how they influence on the toxicological mechanism of chemical mixtures. To reveal this underlying toxicological mechanism of chemical mixtures, a case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum was employed, and both their joint effects and mixture toxicity were observed. Then series of two-step linear regressions were performed to describe the relationships between joint effects, the expected additive toxicities and descriptors of individual chemicals (including concentrations, binding affinity to receptors, octanol/water partition coefficients). Based on the quantitative relationships, the underlying joint toxicological mechanisms were revealed. The result shows that, for mixtures with their joint effects resulting from intracellular chemical reaction, their underlying toxicological mechanism depends on not only their interaction with target proteins, but also their transmembrane actions and their concentrations. In addition, two generic points of toxicological mechanism were proposed including the influencing factors on intracellular chemical reaction and the difference of the toxicological mechanism between single reactive chemicals and their mixtures. This study provided an insight into the understanding of the underlying toxicological mechanism for chemical mixtures with intracellular chemical reaction. - Highlights: • Joint effects of nitriles and aldehydes at non-equitoxic ratios were determined. • A novel descriptor, ligand–receptor interaction energy (E{sub binding}), was employed. • Quantitative relationships for mixtures were developed based on a novel descriptor. • The underlying toxic mechanism was revealed based on quantitative relationships. • Two

Beta Regression Finite Mixture Models of Polarization and Priming

Science.gov (United States)

Smithson, Michael; Merkle, Edgar C.; Verkuilen, Jay

2011-01-01

This paper describes the application of finite-mixture general linear models based on the beta distribution to modeling response styles, polarization, anchoring, and priming effects in probability judgments. These models, in turn, enhance our capacity for explicitly testing models and theories regarding the aforementioned phenomena. The mixture…

Hofmeister effect of salt mixtures on thermo-responsive poly(propylene oxide)

DEFF Research Database (Denmark)

Moghaddam, Saeed Zajforoushan; Thormann, Esben

2015-01-01

of aqueous solutions of poly(propylene oxide) is affected by mixtures of ions with different location in the Hofmeister series. Our results show that the Hofmeister effects of pure salt species are not always linearly additive and that the relative effect of some ions can be reversed depending...... on the composition of the salt mixture as well as by the absolute and relative concentration of the different species. We suggest that these results can lead to a better understanding of the potential role of the Hofmeister effect in regulation of biological processes, which does always take place in salt mixtures...... rather than solutions containing just single salt species....

Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT).

Science.gov (United States)

Maurer, Reinhard J; Reuter, Karsten

2013-07-07

Accurate and efficient simulation of excited state properties is an important and much aspired cornerstone in the study of adsorbate dynamics on metal surfaces. To this end, the recently proposed linear expansion Δ-self-consistent field method by Gavnholt et al. [Phys. Rev. B 78, 075441 (2008)] presents an efficient alternative to time consuming quasi-particle calculations. In this method, the standard Kohn-Sham equations of density-functional theory are solved with the constraint of a non-equilibrium occupation in a region of Hilbert-space resembling gas-phase orbitals of the adsorbate. In this work, we discuss the applicability of this method for the excited-state dynamics of metal-surface mounted organic adsorbates, specifically in the context of molecular switching. We present necessary advancements to allow for a consistent quality description of excited-state potential-energy surfaces (PESs), and illustrate the concept with the application to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find that the explicit inclusion of substrate electronic states modifies the topologies of intra-molecular excited-state PESs of the molecule due to image charge and hybridization effects. While the molecule in gas phase shows a clear energetic separation of resonances that induce isomerization and backreaction, the surface-adsorbed molecule does not. The concomitant possibly simultaneous induction of both processes would lead to a significantly reduced switching efficiency of such a mechanism.

Glass polymorphism in glycerol–water mixtures: I. A computer simulation study

Science.gov (United States)

Jahn, David A.; Wong, Jessina; Bachler, Johannes; Loerting, Thomas

2016-01-01

We perform out-of-equilibrium molecular dynamics (MD) simulations of water–glycerol mixtures in the glass state. Specifically, we study the transformations between low-density (LDA) and high-density amorphous (HDA) forms of these mixtures induced by compression/decompression at constant temperature. Our MD simulations reproduce qualitatively the density changes observed in experiments. Specifically, the LDA–HDA transformation becomes (i) smoother and (ii) the hysteresis in a compression/decompression cycle decreases as T and/or glycerol content increase. This is surprising given the fast compression/decompression rates (relative to experiments) accessible in MD simulations. We study mixtures with glycerol molar concentration χ g = 0–13% and find that, for the present mixture models and rates, the LDA–HDA transformation is detectable up to χ g ≈ 5%. As the concentration increases, the density of the starting glass (i.e., LDA at approximately χ g ≤ 5%) rapidly increases while, instead, the density of HDA remains practically constant. Accordingly, the LDA state and hence glass polymorphism become inaccessible for glassy mixtures with approximately χ g > 5%. We present an analysis of the molecular-level changes underlying the LDA–HDA transformation. As observed in pure glassy water, during the LDA-to-HDA transformation, water molecules within the mixture approach each other, moving from the second to the first hydration shell and filling the first interstitial shell of water molecules. Interestingly, similar changes also occur around glycerol OH groups. It follows that glycerol OH groups contribute to the density increase during the LDA–HDA transformation. An analysis of the hydrogen bond (HB)-network of the mixtures shows that the LDA–HDA transformation is accompanied by minor changes in the number of HBs of water and glycerol. Instead, large changes in glycerol and water coordination numbers occur. We also perform a detailed analysis of the

Microwave dielectric characterization of binary mixture of formamide ...

Indian Academy of Sciences (India)

are fitted to the three different relaxation models [24–27] by the non-linear least squares fit method. It is observed that the Davidson–Cole model is adequate to describe major dispersion of the various solute and solvent mixtures over this fre- quency range. Static dielectric constant and dielectric relaxation time could be.

Microscopic dynamics of binary mixtures and quasi-colloidal systems

International Nuclear Information System (INIS)

Smorenburg, H.E.

1996-01-01

In the study on the title subject two questions are addressed. One is whether the microscopic dynamics of binary mixtures and quasi-colloidal systems can be understood theoretically with kinetic theories for equivalent hard sphere mixtures. The other question that arises is whether the similarity in the dynamics of dense simple fluids and concentrated colloidal suspensions also holds for binary mixtures and quasi-colloidal systems. To answer these questions, we have investigated a number of binary gas mixtures and quasi-colloidal system with different diameter ratios and concentrations. We obtain the experimental dynamic structure factors S expt (κ,ω) of the samples from inelastic neutron scattering. We compare S expt (κ,ω) with the dynamic structure S HS (κ,ω) of an equivalent hard sphere fluid, that we calculate with the Enskog theory. In chapter 2, 3 and 4 we study dense He-Ar gas mixtures (diameter ratio R=1.4, and mass ratio M=10) at low and high Ar concentrations. Experiment and kinetic theory are in good agreement. In chapter 5 we study dilute quasi-colloidal suspensions of fullerene C60 molecules dissolved in liquid CS2. The diameter ratio R=2.2 is larger than in previous experiments while the mass ratio M=9.5 is more or less the same. We obtain the self diffusion coefficient D S of one C60 molecule in CS2 and find D s ≤D SE ≤D E , with D E obtained from kinetic theory and D SE from the Stokes-Einstein description. It appears that both descriptions are relevant but not so accurate. In chapter 6 we study three dense mixtures of neopentane in 40 Ar (diameter ratio R=1.7, mass ratio M=2) at low and high neopentane concentrations. At low concentration, we find a diffusion coefficient of neopentane in Ar, which is in good agreement with kinetic theory and in moderate agreement with the Stokes-Einstein description. At high concentration the collective translational dynamics of neopentane shows a similar behaviour as in dense colloids and simple fluids

Dynamics of elliptic breathers in saturable nonlinear media with linear anisotropy

International Nuclear Information System (INIS)

Liang, Guo; Guo, Qi; Shou, Qian; Ren, Zhanmei

2014-01-01

We have introduced a class of dynamic elliptic breathers in saturable nonlinear media with linear anisotropy. Two kinds of evolution behavior for the dynamic breathers, rotations and molecule-like librations, are both predicted by the variational approach, and confirmed in numerical simulations. The dynamic elliptic breathers can rotate even though they have no initial orbital angular momentum (OAM). As the media are linear anisotropic, OAM is no longer conserved, and hence the angular velocity is not constant but a periodic function of the propagation distance. When the linear anisotropy is large enough, the dynamic elliptic breathers librate like molecules. The dynamic elliptic breathers are present in media with not only saturable nonlinearity but also nonlocal nonlinearity; indeed, they are universal in nonlinear media with linear anisotropy. (paper)

Refractometry for quality control of anesthetic drug mixtures.

Science.gov (United States)

Stabenow, Jennifer M; Maske, Mindy L; Vogler, George A

2006-07-01

Injectable anesthetic drugs used in rodents are often mixed and further diluted to increase the convenience and accuracy of dosing. We evaluated clinical refractometry as a simple and rapid method of quality control and mixing error detection of rodent anesthetic or analgesic mixtures. Dilutions of ketamine, xylazine, acepromazine, and buprenorphine were prepared with reagent-grade water to produce at least 4 concentration levels. The refraction of each concentration then was measured with a clinical refractometer and plotted against the percentage of stock concentration. The resulting graphs were linear and could be used to determine the concentration of single-drug dilutions or to predict the refraction of drug mixtures. We conclude that refractometry can be used to assess the concentration of dilutions of single drugs and can verify the mixing accuracy of drug combinations when the components of the mixture are known and fall within the detection range of the instrument.

Linear study of Kelvin-Helmholtz instability for a viscous compressible fluid

International Nuclear Information System (INIS)

Hallo, L.; Gauthier, S.

1992-01-01

The linear phase of the process leading to a developed turbulence is particularly important for the study of flow stability. A Galerkin spectral method adapted to the study of the mixture layer of one fluid is proposed from a sheared initial velocity profile. An algebraic mapping is developed to improve accuracy near high gradient zone. Validation is obtained by analytic methods for non-viscous flow and multi-domain spectral methods for viscous and compressible flow. Rates of growth are presented for subsonic and slightly supersonic flow. An extension of the method is presented for the study of the linear stability of a mixture with variable concentration and transport properties

Capillary condensation of short-chain molecules.

Science.gov (United States)

Bryk, Paweł; Pizio, Orest; Sokolowski, Stefan

2005-05-15

A density-functional study of capillary condensation of fluids of short-chain molecules confined to slitlike pores is presented. The molecules are modeled as freely jointed tangent spherical segments with a hard core and with short-range attractive interaction between all the segments. We investigate how the critical parameters of capillary condensation of the fluid change when the pore width decreases and eventually becomes smaller than the nominal linear dimension of the single-chain molecule. We find that the dependence of critical parameters for a fluid of dimers and of tetramers on pore width is similar to that of the monomer fluid. On the other hand, for a fluid of chains consisting of a larger number of segments we observe an inversion effect. Namely, the critical temperature of capillary condensation decreases with increasing pore width for a certain interval of values of the pore width. This anomalous behavior is also influenced by the interaction between molecules and pore walls. We attribute this behavior to the effect of conformational changes of molecules upon confinement.

A pulsed plasma jet with the various Ar/N2 mixtures

Science.gov (United States)

Barkhordari, A.; Ganjovi, A.; Mirzaei, I.; Falahat, A.; Rostami Ravari, M. N.

2017-12-01

In this paper, using the Optical Emission Spectroscopy technique, the physical properties of a fabricated pulsed DBD plasma jet are studied. Ar/N2 gaseous mixture is taken as operational gas, and Ar contribution in Ar/N2 mixture is varied from 75 to 95%. Through the optical emission spectra analysis of the pulsed DBD plasma jet, the rotational, vibrational and excitation temperatures and density of electrons in plasma medium of the pulsed plasma jet are obtained. It is seen that, at the wavelength of 750.38 nm, the radiation intensity from the Ar 4p → 4 s transition increases at the higher Ar contributions in Ar/N2 mixture. It is found that, for 95% of Ar presence in the mixture, the emission intensities from argon and molecular nitrogen are higher, and the emission line intensities will increase nonlinearly. In addition, it is observed that the quenching of Ar* by N2 results in the higher intensities of N2 excited molecules. Moreover, at the higher percentages of Ar in Ar/N2 mixture, while all the plasma temperatures are increased, the plasma electron density is reduced.

A Mathematical Model of Membrane Gas Separation with Energy Transfer by Molecules of Gas Flowing in a Channel to Molecules Penetrating this Channel from the Adjacent Channel

Directory of Open Access Journals (Sweden)

Szwast Maciej

2015-06-01

Full Text Available The paper presents the mathematical modelling of selected isothermal separation processes of gaseous mixtures, taking place in plants using membranes, in particular nonporous polymer membranes. The modelling concerns membrane modules consisting of two channels - the feeding and the permeate channels. Different shapes of the channels cross-section were taken into account. Consideration was given to co-current and counter-current flows, for feeding and permeate streams, respectively, flowing together with the inert gas receiving permeate. In the proposed mathematical model it was considered that pressure of gas changes along the length of flow channels was the result of both - the drop of pressure connected with flow resistance, and energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel. The literature on membrane technology takes into account only the drop of pressure connected with flow resistance. Consideration given to energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel constitute the essential novelty in the current study. The paper also presents results of calculations obtained by means of a computer program which used equations of the derived model. Physicochemical data concerning separation of the CO2/CH4 mixture with He as the sweep gas and data concerning properties of the membrane made of PDMS were assumed for calculations.

Effects of Titanate Coupling Agent on Engineering Properties of Asphalt Binders and Mixtures Incorporating LLDPE-CaCO3 Pellet

Directory of Open Access Journals (Sweden)

Mohd Rosli Mohd Hasan

2018-06-01

Full Text Available This study was initiated to evaluate the performance of asphalt binders and mixtures incorporating linear low-density polyethylene- calcium carbonate (LLDPE-CaCO3 pellet, either with or without titanate coupling agent. The detailed manufacturing process of modifier pellets was displayed. The coupling agent was used to enhance the cross-linking between materials by means of winding up covalent bonds or molecule chains, thus improving the performance of composites. In the preparation of modified bitumen, the preheated asphalt binder was mixed with the modifiers using a high shear mixer at 5000 rpm rotational speed for 45 min. Experimental works were conducted to evaluate the performance of asphalt binders in terms of volatile loss, viscosity, rutting potential, and low temperature cracking. Meanwhile, the asphalt mixtures were tested using the flow number test and tensile strength ratio (TSR test. The addition of LLDPE-CaCO3 modifiers and coupling agent does not significantly affect the volatile loss of modified asphalt binders. The addition of modifiers and coupling agent has significantly improved the resistance to permanent deformation of asphalt binders. Even though, the addition of LLDPE-CaCO3 modifier and coupling agent remarkably increased the mixture stiffness that contributed to lower rutting potential, the resistance to low temperature cracking of asphalt binder was not adversely affected. The combination of 1% coupling agent with 3% PECC is optimum dosage for asphalt binder to have satisfactory performance in resistance to moisture damage and rutting.

Small-molecule azomethines: Organic photovoltaics via Schiff base condensation chemistry

OpenAIRE

Petrus, M.L.; Bouwer, R.K.M.; Lafont, U.; Athanasopoulos, S.; Greenham, N.C.; Dingemans, T.J.

2014-01-01

Conjugated small-molecule azomethines for photovoltaic applications were prepared via Schiff base condensation chemistry. Bulk heterojunction (BHJ) devices exhibit efficiencies of 1.2% with MoOx as the hole-transporting layer. The versatility and simplicity of the chemistry is illustrated by preparing a photovoltaic device directly from the reaction mixture without any form of workup.

Direct Importance Estimation with Gaussian Mixture Models

Science.gov (United States)

Yamada, Makoto; Sugiyama, Masashi

The ratio of two probability densities is called the importance and its estimation has gathered a great deal of attention these days since the importance can be used for various data processing purposes. In this paper, we propose a new importance estimation method using Gaussian mixture models (GMMs). Our method is an extention of the Kullback-Leibler importance estimation procedure (KLIEP), an importance estimation method using linear or kernel models. An advantage of GMMs is that covariance matrices can also be learned through an expectation-maximization procedure, so the proposed method — which we call the Gaussian mixture KLIEP (GM-KLIEP) — is expected to work well when the true importance function has high correlation. Through experiments, we show the validity of the proposed approach.

Thermophysical properties of N, N-dimethylacetamide mixtures with n-butanol

Science.gov (United States)

Maharolkar, Aruna P.; Murugkar, A. G.; Khirade, P. W.; Mehrotra, S. C.

2017-09-01

The refraction, dielectric, viscosity, density, data of the binary mixtures of N, N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature.

Nanospiral Formation by Droplet Drying: One Molecule at a Time

Directory of Open Access Journals (Sweden)

Wan Lei

2011-01-01

Full Text Available Abstract We have created nanospirals by self-assembly during droplet evaporation. The nanospirals, 60–70 nm in diameter, formed when solvent mixtures of methanol and m-cresol were used. In contrast, spin coating using only methanol as the solvent produced epitaxial films of stripe nanopatterns and using only m-cresol disordered structure. Due to the disparity in vapor pressure between the two solvents, droplets of m-cresol solution remaining on the substrate serve as templates for the self-assembly of carboxylic acid molecules, which in turn allows the visualization of solution droplet evaporation one molecule at a time.

Long-Lived Ultracold Molecules with Electric and Magnetic Dipole Moments

Science.gov (United States)

Rvachov, Timur M.; Son, Hyungmok; Sommer, Ariel T.; Ebadi, Sepehr; Park, Juliana J.; Zwierlein, Martin W.; Ketterle, Wolfgang; Jamison, Alan O.

2017-10-01

We create fermionic dipolar 23Na 6Li molecules in their triplet ground state from an ultracold mixture of 23Na and 6Li. Using magnetoassociation across a narrow Feshbach resonance followed by a two-photon stimulated Raman adiabatic passage to the triplet ground state, we produce 3 ×1 04 ground state molecules in a spin-polarized state. We observe a lifetime of 4.6 s in an isolated molecular sample, approaching the p -wave universal rate limit. Electron spin resonance spectroscopy of the triplet state was used to determine the hyperfine structure of this previously unobserved molecular state.

On Bayesian Inference under Sampling from Scale Mixtures of Normals

NARCIS (Netherlands)

Fernández, C.; Steel, M.F.J.

1996-01-01

This paper considers a Bayesian analysis of the linear regression model under independent sampling from general scale mixtures of Normals.Using a common reference prior, we investigate the validity of Bayesian inference and the existence of posterior moments of the regression and precision

Evolution of linear chromosomes and multipartite genomes in yeast mitochondria

Science.gov (United States)

Valach, Matus; Farkas, Zoltan; Fricova, Dominika; Kovac, Jakub; Brejova, Brona; Vinar, Tomas; Pfeiffer, Ilona; Kucsera, Judit; Tomaska, Lubomir; Lang, B. Franz; Nosek, Jozef

2011-01-01

Mitochondrial genome diversity in closely related species provides an excellent platform for investigation of chromosome architecture and its evolution by means of comparative genomics. In this study, we determined the complete mitochondrial DNA sequences of eight Candida species and analyzed their molecular architectures. Our survey revealed a puzzling variability of genome architecture, including circular- and linear-mapping and multipartite linear forms. We propose that the arrangement of large inverted repeats identified in these genomes plays a crucial role in alterations of their molecular architectures. In specific arrangements, the inverted repeats appear to function as resolution elements, allowing genome conversion among different topologies, eventually leading to genome fragmentation into multiple linear DNA molecules. We suggest that molecular transactions generating linear mitochondrial DNA molecules with defined telomeric structures may parallel the evolutionary emergence of linear chromosomes and multipartite genomes in general and may provide clues for the origin of telomeres and pathways implicated in their maintenance. PMID:21266473

Control of π-Electron Rotations in Chiral Aromatic Molecules Using Intense Laser Pulses

Science.gov (United States)

Kanno, Manabu; Kono, Hirohiko; Fujimura, Yuichi

Our recent theoretical studies on laser-induced π-electron rotations in chiral aromatic molecules are reviewed. π electrons of a chiral aromatic molecule can be rotated along its aromatic ring by a nonhelical, linearly polarized laser pulse. An ansa aromatic molecule with a six-membered ring, 2,5-dichloro[n](3,6) pyrazinophane, which belongs to a planar-chiral molecule group, and its simplified molecule 2,5-dichloropyrazine are taken as model molecules. Electron wavepacket simulations in the frozen-molecular-vibration approximation show that the initial direction of π-electron rotation depends on the polarization direction of a linearly polarized laser pulse applied. Consecutive unidirectional rotation can be achieved by applying a sequence of linearly polarized pump and dump pulses to prevent reverse rotation. Optimal control simulations of π-electron rotation show that another controlling factor for unidirectional rotation is the relative optical phase between the different frequency components of an incident pulse in addition to photon polarization direction. Effects of nonadiabatic coupling between π-electron rotation and molecular vibrations are also presented, where the constraints of the frozen approximation are removed. The angular momentum gradually decays mainly owing to nonadiabatic coupling, while the vibrational amplitudes greatly depend on their rotation direction. This suggests that the direction of π-electron rotation on an attosecond timescale can be identified by detecting femtosecond molecular vibrations.

Equilibrium moisture content of waste mixtures from post-consumer carton packaging.

Science.gov (United States)

Bacelos, M S; Freire, J T

2012-01-01

The manufacturing of boards and roof tiles is one of the routes to reuse waste from the recycled-carton-packaging process. Such a process requires knowledge of the hygroscopic behaviour of these carton-packaging waste mixtures in order to guarantee the quality of the final product (e.g. boards and roof tiles). Thus, with four carton-packaging waste mixtures of selected compositions (A, B, C and D), the sorption isotherms were obtained at air temperature of 20, 40 and 60 degrees C by using the static method. This permits one to investigate which model can relate the equilibrium moisture content of the mixture with that of a pure component through the mass fraction of each component in the mixtures. The results show that the experimental data can be well described by the weighted harmonic mean model. This suggests that the mean equilibrium moisture content of the carton-packaging mixture presents a non-linear relationship with each single, pure compound.

Experimental and theoretical characterization of a multi-wavelength DBD-driven exciplex lamp operated with mercury bromide/rare gas mixtures

International Nuclear Information System (INIS)

Guivan, Mykola M; Malinina, Antonina A; Brablec, Antonin

2011-01-01

Emission spectra from an atmospheric-pressure dielectric barrier discharge (DBD) with HgBr 2 /He or HgBr 2 /Xe/Kr mixtures, as well as the electrical characteristics, were investigated at repetition frequencies of sinusoidal voltage pulses up to 125 kHz. In the spectra, the study revealed radiation from HgBr(B-X, C-X) exciplex molecules, atomic lines of mercury and rare gases, and in mixtures with xenon, radiation of XeBr(B-X, B-A) exciplex molecules. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma were discussed. The electron energy distribution function, the specific energy lost in the processes involving electrons, the electron temperature and density, and the rate constants of elastic and inelastic electron scattering by the components of the working mixture were calculated as functions of the reduced field E/N. The high-frequency atmospheric-pressure barrier discharge in mixtures of mercury dibromide with gases can be used in multi-wavelength exciplex lamps, operating in the UV and visible regions.

Experimental and theoretical characterization of a multi-wavelength DBD-driven exciplex lamp operated with mercury bromide/rare gas mixtures

Energy Technology Data Exchange (ETDEWEB)

Guivan, Mykola M; Malinina, Antonina A [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine); Brablec, Antonin, E-mail: m_guivan@rambler.ru [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic)

2011-06-08

Emission spectra from an atmospheric-pressure dielectric barrier discharge (DBD) with HgBr{sub 2}/He or HgBr{sub 2}/Xe/Kr mixtures, as well as the electrical characteristics, were investigated at repetition frequencies of sinusoidal voltage pulses up to 125 kHz. In the spectra, the study revealed radiation from HgBr(B-X, C-X) exciplex molecules, atomic lines of mercury and rare gases, and in mixtures with xenon, radiation of XeBr(B-X, B-A) exciplex molecules. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma were discussed. The electron energy distribution function, the specific energy lost in the processes involving electrons, the electron temperature and density, and the rate constants of elastic and inelastic electron scattering by the components of the working mixture were calculated as functions of the reduced field E/N. The high-frequency atmospheric-pressure barrier discharge in mixtures of mercury dibromide with gases can be used in multi-wavelength exciplex lamps, operating in the UV and visible regions.

Hydration of alcohol clusters in 1-propanol-water mixture studied by quasielastic neutron scattering and an interpretation of anomalous excess partial molar volume.

Science.gov (United States)

Misawa, M; Inamura, Y; Hosaka, D; Yamamuro, O

2006-08-21

Quasielastic neutron scattering measurements have been made for 1-propanol-water mixtures in a range of alcohol concentration from 0.0 to 0.167 in mole fraction at 25 degrees C. Fraction alpha of water molecules hydrated to fractal surface of alcohol clusters in 1-propanol-water mixture was obtained as a function of alcohol concentration. Average hydration number N(ws) of 1-propanol molecule is derived from the value of alpha as a function of alcohol concentration. By extrapolating N(ws) to infinite dilution, we obtain values of 12-13 as hydration number of isolated 1-propanol molecule. A simple interpretation of structural origin of anomalous excess partial molar volume of water is proposed and as a result a simple equation for the excess partial molar volume is deduced in terms of alpha. Calculated values of the excess partial molar volumes of water and 1-propanol and the excess molar volume of the mixture are in good agreement with experimental values.

Study the multi-photon absorption process in two types of molecules

International Nuclear Information System (INIS)

Al-azawi, H.R.

1986-01-01

The aim of the present work was to study the multi-photon absorption process in two types of molecules; spherical top such as SF 6 molecules and assymetric top such as CHOOH and C 2 H 4 molecules. This work also aimed to study the effect of buffer gas pressure (Ar), which is transparent to the infrared (IR) laser on the multiphoton absorption of both types of molecules. A pulsed (TEA) CO 2 laser was used as a source which generates multi-lines in the IR-region of the spectrum and an optoacoustic detector was used to detect the energy absorbed by the molecules. In this study, the relaxation process was found to be faster in the heavy molecules than that in the light ones. A limit in the Ar pressure was observed. Below this limit, the gas acted as an active buffer gas and above it, the multi-photon absorption process was quenched. This work also aimed to study the multi-photon absorption spectrum for the CHOOH molecules in the range (1067-1090 cm -1 ). This spectrum was found to be consistent with the linear absorption spectrum obtained for the same range. The density of the vibrational states as a function of the vibrational energy was studied for the molecules SF 6 , CHOOH and C 2 H 4 . The results were used to interpret (i) the difference in the energy absorbed by difference molecules at the same energy density and (ii) the non-linearity in the multi-photon absorption for CHOOH molecules. 1 tab.; 40 figs.; 70 refs

Partition Coefficients of Organic Molecules in Squalane and Water/Ethanol Mixtures by Molecular Dynamics Simulations

DEFF Research Database (Denmark)

Lundsgaard, Rasmus; Kontogeorgis, Georgios; Economou, Ioannis G.

2011-01-01

coefficient can be estimated for both a small hydrophilic and a hydrophobic organic molecules between squalane (used here to mimic low density poly ethylene) and water/ethanol solutes using thermodynamic integration to calculate the free energy of solvation. Molecular dynamics simulations are performed, using...... the GROMACS software, by slowly decoupling of firstly the electrostatic and then the Lennard–Jones interactions between molecules in the simulation box. These calculations depend very much on the choice of force field. Two force fields have been tested in this work, the TraPPE-UA (united-atom) and the OPLS...

Solvation structures of lithium halides in methanol–water mixtures

International Nuclear Information System (INIS)

Sarkar, Atanu; Dixit, Mayank Kumar; Tembe, B.L.

2015-01-01

Highlights: • Potentials of mean force for Li + -halides are calculated in methanol–water mixtures. • Stable CIP for x methanol = 1.0 becomes unstable at and below x methanol = 0.75. • The Li + ion is preferentially solvated by methanol molecules. • The halide ions are preferentially solvated by water molecules. - Abstract: The potentials of mean force (PMFs) for the ion pairs, Li + −Cl − , Li + −Br − and Li + −I − have been calculated in five methanol–water compositions. The results obtained are verified by trailing the trajectories and calculating the ion pair distance residence times. Local structures around the ions are studied using the radial distribution functions, density profiles, orientational correlation functions, running coordination numbers and excess coordination numbers. The major change in PMF is observed as the methanol mole fraction (x methanol ) is changed from 1.0 to 0.75. The stable contact ion pair occurring for x methanol = 1.0 becomes unstable at and below x methanol = 0.75. The preferential solvation data show that the halide ions are always preferentially solvated by water molecules. Although the lithium ion is preferentially solvated by methanol molecules, there is significant affinity towards water molecules as well

Vibrational-rotational relaxation of the simplest hydrogen-containing molecules (review)

International Nuclear Information System (INIS)

Molevich, N.E.; Oraevskii, A.N.

1987-01-01

In connection with the development of chemical lasers much attention is now devoted to the study of kinetic processes is gaseous mixtures containing the hydrogen halides. Vibrational relaxation of molecules if primarily studied without specifying its relation to the rational levels. Rotational relaxation is regarded a priori as faster than vibrational relaxation, so that the population of the rotational levels is assumed to be in equilibrium. This approach to the relaxation of hydrogen halide molecules (and other diatomic hydrogen-containing molecules), however, is unable to explain satisfactorily the results of the papers discussed below. An analysis of the data obtained in these papers leads to the conclusion that the general picture of relaxation in diatomic hydrogen-containing molecules must be viewed as a unified process of vibrational and rotational relaxation. It is shown that those effects observed during vibrational relaxation of such molecules which are unusual from the standpoint of the theory of vibrational-translational relaxation are well explained in terms of intermolecular vibrational-rotational relaxation together with pure rotational relaxation

Coarse-grained modelling of triglyceride crystallisation: a molecular insight into tripalmitin tristearin binary mixtures by molecular dynamics simulations

Science.gov (United States)

Pizzirusso, Antonio; Brasiello, Antonio; De Nicola, Antonio; Marangoni, Alejandro G.; Milano, Giuseppe

2015-12-01

The first simulation study of the crystallisation of a binary mixture of triglycerides using molecular dynamics simulations is reported. Coarse-grained models of tristearin (SSS) and tripalmitin (PPP) molecules have been considered. The models have been preliminarily tested in the crystallisation of pure SSS and PPP systems. Two different quenching procedures have been tested and their performances have been analysed. The structures obtained from the crystallisation procedures show a high orientation order and a high content of molecules in the tuning fork conformation, comparable with the crystalline α phase. The behaviour of melting temperatures for the α phase of the mixture SSS/PPP obtained from the simulations is in qualitative agreement with the behaviour that was experimentally determined.

Coarse-grained modelling of triglyceride crystallisation: a molecular insight into tripalmitin tristearin binary mixtures by molecular dynamics simulations

International Nuclear Information System (INIS)

Pizzirusso, Antonio; De Nicola, Antonio; Milano, Giuseppe; Brasiello, Antonio; Marangoni, Alejandro G

2015-01-01

The first simulation study of the crystallisation of a binary mixture of triglycerides using molecular dynamics simulations is reported. Coarse-grained models of tristearin (SSS) and tripalmitin (PPP) molecules have been considered. The models have been preliminarily tested in the crystallisation of pure SSS and PPP systems. Two different quenching procedures have been tested and their performances have been analysed. The structures obtained from the crystallisation procedures show a high orientation order and a high content of molecules in the tuning fork conformation, comparable with the crystalline α phase. The behaviour of melting temperatures for the α phase of the mixture SSS/PPP obtained from the simulations is in qualitative agreement with the behaviour that was experimentally determined. (paper)

Diffusion and infrared properties of molecules in ice mantles

International Nuclear Information System (INIS)

Schmitt, B.; Grim, R.; Greenberg, J.M.

1989-01-01

Within dense molecular clouds the formation of frozen icy mantles on interstellar dust grains is thought to be the result of various growth conditions. The molecules, which make up the ice mantles are probably completely mixed. To study the physical properties of such ice mixtures the experiments were performed on the evaporation processes and on the spectroscopic properties of CO, CO2, and CH4 in water rich ices. The decrease in concentration of volatile molecules in ice samples deposited at 10 K and subsequently heated is found to occur essentially in two steps. The first one, corresponding to an evaporation of part of the volatile molecules, starts at about 25 K for CO, 32 K for CH4, and 70 K for CO2. During the crystallization of H2O ice at temperatures greater than 120 K a second evaporation occurs leading to the complete disappearance of the volatile molecules in the solid phase. The main astrophysical implications of the diffusion and spectroscopic behaviors are presented. The possible effects of a heating source on the fraction of volatile molecules, such as CO trapped in grain mantles, are discussed

Volumetric and viscometric study of molecular interactions in the mixtures of some secondary alcohols with equimolar mixture of ethanol and N,N-dimethylacetamide at 308.15 K

International Nuclear Information System (INIS)

Sreekanth, K.; Sravana Kumar, D.; Kondaiah, M.; Krishna Rao, D.

2011-01-01

Densities and viscosities of mixtures of isopropanol, isobutanol and isoamylalcohol with equimolar mixture of ethanol and N,N-dimethylacetamide have been measured at 308.15 K over the entire composition range. Deviations in viscosity, excess molar volume and excess Gibb's free energy of activation of viscous flow have been calculated from the experimental values of densities and viscosities. Excess properties have been fitted to the Redlich-Kister type polynomial equation and the corresponding standard deviations have been calculated. The experimental data of viscosity have been used to test the applicability of empirical relations of Grunberg-Nissan, Hind-McLaughlin, Katti-Chaudhary and Heric-Brewer for the systems studied. Molecular interactions in the liquid mixtures have been investigated in the light of variation of deviation and of excess values in evaluated properties. -- Research highlights: → Volumetric and viscometric studies of liquid mixtures are useful in pharmacy field. → Molecular interactions in ethanol and N,N-dimethylacetamide with alcohols are studied. → Weak interactions observed due to rupture of hydrogen bond between alcohol molecules. → Measured viscosity values compared with theoretical values obtained by polynomials.

Reduced chemical kinetic model of detonation combustion of one- and multi-fuel gaseous mixtures with air

Science.gov (United States)

Fomin, P. A.

2018-03-01

Two-step approximate models of chemical kinetics of detonation combustion of (i) one hydrocarbon fuel CnHm (for example, methane, propane, cyclohexane etc.) and (ii) multi-fuel gaseous mixtures (∑aiCniHmi) (for example, mixture of methane and propane, synthesis gas, benzene and kerosene) are presented for the first time. The models can be used for any stoichiometry, including fuel/fuels-rich mixtures, when reaction products contain molecules of carbon. Owing to the simplicity and high accuracy, the models can be used in multi-dimensional numerical calculations of detonation waves in corresponding gaseous mixtures. The models are in consistent with the second law of thermodynamics and Le Chatelier's principle. Constants of the models have a clear physical meaning. The models can be used for calculation thermodynamic parameters of the mixture in a state of chemical equilibrium.

On the origin of organic molecules in interstellar space and some of its consequences

International Nuclear Information System (INIS)

Johansson, K.L.V.

1981-01-01

The possible sources of complex organic molecules observed in the interstellar space are discussed. It is found that a leakage from lifebearing planets cannot possibly explain the observed amounts of complex organic molecules. They are probably formed in interstellar clouds, either free in space or on the surface of grains. This opens the possibility that planets (also the earth) moving through such clouds may have collected appreciable amounts of complex organic molecules. It would therefore be feasible to perform experiments like the Urey-Miller's, starting with a considerably more complex mixture than the traditional one. (Auth.)

Densities and volumetric properties of (acetonitrile+an amide) binary mixtures at temperatures between 293.15K and 318.15K

International Nuclear Information System (INIS)

Nain, Anil Kumar

2006-01-01

The densities of binary mixtures of acetonitrile (ACN) with formamide (FA), N,N-dimethylformamide (DMF), N-methylacetamide (NMA), and N,N-dimethylacetamide (DMA), including those of pure liquids, over the entire composition range were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K and atmospheric pressure. From the experimental data, the excess molar volume, V m E , and partial molar volumes, V-bar m,1 and V-bar m,2 , were calculated over whole composition range. The variation of these parameters with composition and temperature of the mixtures has been discussed in terms of molecular interaction in these mixtures. The V m E values were found negative for all the mixtures and at each temperature studied, indicating the presence of specific interactions between ACN and amide molecules. The extent of negative deviations in V m E values follows the order: FA>NMA>DMA>DMF. It is observed that the V m E values depend upon the positions of methyl groups in these amide molecules

Excess molar volume and viscosity deviation for binary mixtures of γ-butyrolactone with dimethyl sulfoxide

International Nuclear Information System (INIS)

Krakowiak, Joanna; Śmiechowski, Maciej

2017-01-01

Highlights: • Densities and viscosities of DMSO-GBL binary liquid mixtures were measured. • The volumetric parameters and excess quantities were obtained. • Ab initio calculations were performed for single molecules and dimers in the studied mixture. • The interactions in solutions are weaker than in pure solvents. - Abstract: The densities of binary liquid mixtures of dimethyl sulfoxide and γ-butyrolactone at (293.15, 298.15, 303.15 and 313.15) K and viscosity at T = 298.15 K have been measured at atmospheric pressure over the entire range of concentration. From these data the excess molar volumes V E at (293.15, 298.15, 303.15 and 313.15) K and the viscosity deviation, the excess entropy, and the excess Gibbs energy of activation for viscous flow at T = 298.15 K have been determined. These data were mathematically represented by the Redlich-Kister polynomial. Partial and apparent molar volumes have been calculated for better understanding of the interactions in the binary systems. The obtained data indicate the lack of specific interactions between unlike molecules, which seem to be a little weaker as compared to the interactions in pure solvents.

Iterative Mixture Component Pruning Algorithm for Gaussian Mixture PHD Filter

Directory of Open Access Journals (Sweden)

Xiaoxi Yan

2014-01-01

Full Text Available As far as the increasing number of mixture components in the Gaussian mixture PHD filter is concerned, an iterative mixture component pruning algorithm is proposed. The pruning algorithm is based on maximizing the posterior probability density of the mixture weights. The entropy distribution of the mixture weights is adopted as the prior distribution of mixture component parameters. The iterative update formulations of the mixture weights are derived by Lagrange multiplier and Lambert W function. Mixture components, whose weights become negative during iterative procedure, are pruned by setting corresponding mixture weights to zeros. In addition, multiple mixture components with similar parameters describing the same PHD peak can be merged into one mixture component in the algorithm. Simulation results show that the proposed iterative mixture component pruning algorithm is superior to the typical pruning algorithm based on thresholds.

Density functional theory for adsorption of gas mixtures in metal-organic frameworks.

Science.gov (United States)

Liu, Yu; Liu, Honglai; Hu, Ying; Jiang, Jianwen

2010-03-04

In this work, a recently developed density functional theory in three-dimensional space was extended to the adsorption of gas mixtures. Weighted density approximations to the excess free energy with different weighting functions were adopted for both repulsive and attractive contributions. An equation of state for hard-sphere mixtures and a modified Benedict-Webb-Rubin equation for Lennard-Jones mixtures were used to estimate the excess free energy of a uniform fluid. The theory was applied to the adsorption of CO(2)/CH(4) and CO(2)/N(2) mixtures in two metal-organic frameworks: ZIF-8 and Zn(2)(BDC)(2)(ted). To validate the theoretical predictions, grand canonical Monte Carlo simulations were also conducted. The predicted adsorption and selectivity from DFT were found to agree well with the simulation results. CO(2) has stronger adsorption than CH(4) and N(2), particularly in Zn(2)(BDC)(2)(ted). The selectivity of CO(2) over CH(4) or N(2) increases with increasing pressure as attributed to the cooperative interactions of adsorbed CO(2) molecules. The composition of the gas mixture exhibits a significant effect on adsorption but not on selectivity.

Microscopic Theory of Coupled Slow Activated Dynamics in Glass-Forming Binary Mixtures.

Science.gov (United States)

Zhang, Rui; Schweizer, Kenneth S

2018-04-05

The Elastically Collective Nonlinear Langevin Equation theory for one-component viscous liquids and suspensions is generalized to treat coupled slow activated relaxation and diffusion in glass-forming binary sphere mixtures of any composition, size ratio, and interparticle interactions. A trajectory-level dynamical coupling parameter concept is introduced to construct two coupled dynamic free energy functions for the smaller penetrant and larger matrix particle. A two-step dynamical picture is proposed where the first-step process involves matrix-facilitated penetrant hopping quantified in a self-consistent manner based on a temporal coincidence condition. After penetrants dynamically equilibrate, the effectively one-component matrix particle dynamics is controlled by a new dynamic free energy (second-step process). Depending on the time scales associated with the first- and second-step processes, as well as the extent of matrix-correlated facilitation, distinct physical scenarios are predicted. The theory is implemented for purely hard-core interactions, and addresses the glass transition based on variable kinetic criteria, penetrant-matrix coupled activated relaxation, self-diffusion of both species, dynamic fragility, and shear elasticity. Testable predictions are made. Motivated by the analytic ultralocal limit idea derived for pure hard sphere fluids, we identify structure-thermodynamics-dynamics relationships. As a case study for molecule-polymer thermal mixtures, the chemically matched fully miscible polystyrene-toluene system is quantitatively studied based on a predictive mapping scheme. The resulting no-adjustable-parameter results for toluene diffusivity and the mixture glass transition temperature are in good agreement with experiment. The theory provides a foundation to treat diverse dynamical problems in glass-forming mixtures, including suspensions of colloids and nanoparticles, polymer-molecule liquids, and polymer nanocomposites.

Synthesis of variable size molecules using poly-homologation of boron compounds

International Nuclear Information System (INIS)

Goddard, J.P.

2002-01-01

During this work, we developed a method of original synthesis allowing to lead mixtures of molecules of variable size with an aim of discovering new chelating molecules of cesium. This method utilizes a reaction of poly-homologation of borated compounds with the nucleophilic ones comprising a grouping leaving in alpha of the negative charge. We tested various families from nucleophilic like anions of sulfones, sulfonium ylides, anions of hydrazones, tri-methylsilyldiazomethane and arsonium ylides. The first three families did not allow us to carry out reactions of poly-homologation. The tri-methylsilyldiazomethane possesses not either the capacity to carry out reactions successive insertions but this property was exploited to propose a chemical conversion of olefinic hydrocarbon into alkyl-methanol corresponding. The arsonium ylides made it possible to carry out reactions of poly-homologation with boronates and boranes. The alkyl-arsonium ylides were used to form polymers of controlled size having a ramification on each carbon atom of the principal chain. This type of polymer is not accessible by the current methods of polymerization. The allyl-arsonium ylides have a particular reactivity since the allyl boranes formed during the insertion reactions undergo a sigma-tropic [1,3] rearrangement before reacting again with a ylide. It is thus possible to lead with polymers of big size to which the structure is close to that of the natural rubber. By this method it is possible to lead with linear or cyclic polymers. This method is currently under development at the laboratory to form chelating structures of cesium. (author) [fr

Change of hydrogen bonding structure in ionic liquid mixtures by anion type

Science.gov (United States)

Cha, Seoncheol; Kim, Doseok

2018-05-01

Ionic liquid mixtures have gained attention as a way of tuning material properties continuously with composition changes. For some mixture systems, physicochemical properties such as excess molar volume have been found to be significantly different from the value expected by linear interpolation, but the origin of this deviation is not well understood yet. The microstructure of the mixture, which can range from an ideal mixture of two initial consisting ionic liquids to a different structure from those of pure materials, has been suggested as the origin of the observed deviation. The structures of several different ionic liquid mixtures are studied by IR spectroscopy to confirm this suggestion, as a particular IR absorption band (νC(2)-D) for the moiety participating in the hydrogen bonding changes sensitively with the change of the anion in the ionic liquid. The absorbance of νC(2)-D changes proportionally with the composition, and a relatively small excess molar volume is observed for the mixtures containing an electronegative halide anion. By contrast, the absorbance changes nonlinearly, and the excess molar volumes are larger for the mixtures of which one of the anions has multiple interaction sites.

Molecular dynamics simulation of a binary mixture near the lower critical point

Energy Technology Data Exchange (ETDEWEB)

Pousaneh, Faezeh; Edholm, Olle, E-mail: oed@kth.se [Theoretical Biological Physics, Department of Theoretical Physics, Royal Institute of Technology (KTH), AlbaNova University Center, SE-106 91 Stockholm (Sweden); Maciołek, Anna [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)

2016-07-07

2,6-lutidine molecules mix with water at high and low temperatures but in a wide intermediate temperature range a 2,6-lutidine/water mixture exhibits a miscibility gap. We constructed and validated an atomistic model for 2,6-lutidine and performed molecular dynamics simulations of 2,6-lutidine/water mixture at different temperatures. We determined the part of demixing curve with the lower critical point. The lower critical point extracted from our data is located close to the experimental one. The estimates for critical exponents obtained from our simulations are in a good agreement with the values corresponding to the 3D Ising universality class.

Bond-based linear indices of the non-stochastic and stochastic edge-adjacency matrix. 1. Theory and modeling of ChemPhys properties of organic molecules.

Science.gov (United States)

Marrero-Ponce, Yovani; Martínez-Albelo, Eugenio R; Casañola-Martín, Gerardo M; Castillo-Garit, Juan A; Echevería-Díaz, Yunaimy; Zaldivar, Vicente Romero; Tygat, Jan; Borges, José E Rodriguez; García-Domenech, Ramón; Torrens, Francisco; Pérez-Giménez, Facundo

2010-11-01

Novel bond-level molecular descriptors are proposed, based on linear maps similar to the ones defined in algebra theory. The kth edge-adjacency matrix (E(k)) denotes the matrix of bond linear indices (non-stochastic) with regard to canonical basis set. The kth stochastic edge-adjacency matrix, ES(k), is here proposed as a new molecular representation easily calculated from E(k). Then, the kth stochastic bond linear indices are calculated using ES(k) as operators of linear transformations. In both cases, the bond-type formalism is developed. The kth non-stochastic and stochastic total linear indices are calculated by adding the kth non-stochastic and stochastic bond linear indices, respectively, of all bonds in molecule. First, the new bond-based molecular descriptors (MDs) are tested for suitability, for the QSPRs, by analyzing regressions of novel indices for selected physicochemical properties of octane isomers (first round). General performance of the new descriptors in this QSPR studies is evaluated with regard to the well-known sets of 2D/3D MDs. From the analysis, we can conclude that the non-stochastic and stochastic bond-based linear indices have an overall good modeling capability proving their usefulness in QSPR studies. Later, the novel bond-level MDs are also used for the description and prediction of the boiling point of 28 alkyl-alcohols (second round), and to the modeling of the specific rate constant (log k), partition coefficient (log P), as well as the antibacterial activity of 34 derivatives of 2-furylethylenes (third round). The comparison with other approaches (edge- and vertices-based connectivity indices, total and local spectral moments, and quantum chemical descriptors as well as E-state/biomolecular encounter parameters) exposes a good behavior of our method in this QSPR studies. Finally, the approach described in this study appears to be a very promising structural invariant, useful not only for QSPR studies but also for similarity

Linear and Nonlinear Multiset Canonical Correlation Analysis (invited talk)

DEFF Research Database (Denmark)

Hilger, Klaus Baggesen; Nielsen, Allan Aasbjerg; Larsen, Rasmus

2002-01-01

This paper deals with decompositioning of multiset data. Friedman's alternating conditional expectations (ACE) algorithm is extended to handle multiple sets of variables of different mixtures. The new algorithm finds estimates of the optimal transformations of the involved variables that maximize...... the sum of the pair-wise correlations over all sets. The new algorithm is termed multi-set ACE (MACE) and can find multiple orthogonal eigensolutions. MACE is a generalization of the linear multiset correlations analysis (MCCA). It handles multivariate multisets of arbitrary mixtures of both continuous...

Heterogeneous structure and solvation dynamics of DME/water binary mixtures: A combined spectroscopic and simulation investigation

Science.gov (United States)

Das Mahanta, Debasish; Rana, Debkumar; Patra, Animesh; Mukherjee, Biswaroop; Mitra, Rajib Kumar

2018-05-01

Water is often found in (micro)-heterogeneous environments and therefore it is necessary to understand their H-bonded network structure in such altered environments. We explore the structure and dynamics of water in its binary mixture with relatively less polar small biocompatible amphiphilic molecule 1,2-Dimethoxyethane (DME) by a combined spectroscopic and molecular dynamics (MD) simulation study. Picosecond (ps) resolved fluorescence spectroscopy using coumarin 500 as the fluorophore establishes a non-monotonic behaviour of the mixture. Simulation studies also explore the various possible H-bond formations between water and DME. The relative abundance of such different water species manifests the heterogeneity in the mixture.

Spectral mixture analyses of hyperspectral data acquired using a tethered balloon

Science.gov (United States)

Chen, Xuexia; Vierling, Lee

2006-01-01

Tethered balloon remote sensing platforms can be used to study radiometric issues in terrestrial ecosystems by effectively bridging the spatial gap between measurements made on the ground and those acquired via airplane or satellite. In this study, the Short Wave Aerostat-Mounted Imager (SWAMI) tethered balloon-mounted platform was utilized to evaluate linear and nonlinear spectral mixture analysis (SMA) for a grassland-conifer forest ecotone during the summer of 2003. Hyperspectral measurement of a 74-m diameter ground instantaneous field of view (GIFOV) attained by the SWAMI was studied. Hyperspectral spectra of four common endmembers, bare soil, grass, tree, and shadow, were collected in situ, and images captured via video camera were interpreted into accurate areal ground cover fractions for evaluating the mixture models. The comparison between the SWAMI spectrum and the spectrum derived by combining in situ spectral data with video-derived areal fractions indicated that nonlinear effects occurred in the near infrared (NIR) region, while nonlinear influences were minimal in the visible region. The evaluation of hyperspectral and multispectral mixture models indicated that nonlinear mixture model-derived areal fractions were sensitive to the model input data, while the linear mixture model performed more stably. Areal fractions of bare soil were overestimated in all models due to the increased radiance of bare soil resulting from side scattering of NIR radiation by adjacent grass and trees. Unmixing errors occurred mainly due to multiple scattering as well as close endmember spectral correlation. In addition, though an apparent endmember assemblage could be derived using linear approaches to yield low residual error, the tree and shade endmember fractions calculated using this technique were erroneous and therefore separate treatment of endmembers subject to high amounts of multiple scattering (i.e. shadows and trees) must be done with caution. Including the

Carbon 13 nuclear magnetic resonance chemical shifts empiric calculations of polymers by multi linear regression and molecular modeling

International Nuclear Information System (INIS)

Da Silva Pinto, P.S.; Eustache, R.P.; Audenaert, M.; Bernassau, J.M.

1996-01-01

This work deals with carbon 13 nuclear magnetic resonance chemical shifts empiric calculations by multi linear regression and molecular modeling. The multi linear regression is indeed one way to obtain an equation able to describe the behaviour of the chemical shift for some molecules which are in the data base (rigid molecules with carbons). The methodology consists of structures describer parameters definition which can be bound to carbon 13 chemical shift known for these molecules. Then, the linear regression is used to determine the equation significant parameters. This one can be extrapolated to molecules which presents some resemblances with those of the data base. (O.L.). 20 refs., 4 figs., 1 tab

Thermodynamic study of (heptane + amine) mixtures. III: Excess and partial molar volumes in mixtures with secondary, tertiary, and cyclic amines at 298.15 K

International Nuclear Information System (INIS)

Lepori, Luciano; Gianni, Paolo; Spanedda, Andrea; Matteoli, Enrico

2011-01-01

Graphical abstract: Highlights: → Excess volumes of (sec., tert., or cyclic amines + heptane) mixtures. → Excess volumes are positive for small size amines and decrease as the size increases. → Group contributions to predict the partial molar volumes of amines in heptane. → The void volume is larger for sec. and tert. than for linear amines in heptane. → The void volume is much smaller for cyclic than for linear amines in heptane. - Abstract: Excess molar volumes V E at 298.15 K were determined by means of a vibrating tube densimeter for binary mixtures of {heptane + open chain secondary (diethyl to dibutyl) and tertiary (triethyl to tripentyl) amines} as well as for cyclic imines (C 2 , C 3 , C 4 , C 6 , and C 7 ) and primary cycloalkylamines (C 5 , C 6 , C 7 , and C 12 ). The V E values were found positive for mixtures involving small size amines, with V E decreasing as the size increases. Negative V E 's were found for tributyl- and tripentylamine, heptamethylenimine, and cyclododecylamine. Mixtures of heptane with cycloheptylamine showed an s-shaped curve. Partial molar volumes V 0 of amines at infinite dilution in heptane were obtained from V E and compared with V 0 of hydrocarbons and other classes of organic compounds taken from literature. An additivity scheme, based on the intrinsic volume approach, was applied to estimate group (CH 3 , CH 2 , CH, C, NH 2 , NH, N, OH, O, CO, and COO) contributions to V 0 . These contributions, the effect of cyclization on V 0 , and the limiting slope of the apparent excess molar volumes were discussed in terms of solute-solvent and solute-solute interactions.

Photon-assisted tunneling in a Fe-8 single-molecule magnet

OpenAIRE

Sorace, L.; Wernsdorfer, W.; Thirion, C.; Barra, A. L.; Pacchioni, M.; Mailly, D.; Barbara, B.

2003-01-01

The low temperature spin dynamics of a Fe8 Single-Molecule Magnet was studied under circularly polarized electromagnetic radiation allowing us to establish clearly photon-assisted tunneling. This effect, while linear at low power, becomes highly non-linear above a relatively low power threshold. This non-linearity is attributed to the nature of the coupling of the sample to the thermostat.These results are of great importance if such systems are to be used as quantum computers.

Initial density fluctuations effects on the microphase separation in ramified polymer mixture

Energy Technology Data Exchange (ETDEWEB)

Ghaouar, N. [Laboratoire de Physique de la Matiere Molle, Faculte des Sciences de Tunis, Campus Universitaire 2092 (Tunisia) and Institut National des Sciences Appliquees et de Technologie, INSAT, Centre Urbain Nord, BP. 676, Tunis (Tunisia)]. E-mail: naoufel-ghaouar@lycos.com

2007-02-19

Our study focuses on the initial density fluctuations effects on microphase separation in ramified polymer mixture. For this purpose, we introduce a screening length {kappa} by considering the condition that the scattered intensity should not be changed by cross-linking. We recover that {kappa}{sup 2}{approx}C/({chi}-{chi}{sub i}), where C is the rigidity constant of the network and {chi} the Flory parameter. Three regimes versus the temperature of the mixture are discussed. The kinetics of the microphase separation is also studied through the relaxation rate. The derived relaxation rate evolution relative to ramified polymers mixture must be compared to that relative to a linear polymer mixture. Finally, we discuss the solvent effect on the microphase separation and we show that the initial fluctuations have little importance because of the excluded volume interaction.

Differential expression among tissues in morbidly obese individuals using a finite mixture model under BLUP approach

DEFF Research Database (Denmark)

Kogelman, Lisette; Trabzuni, Daniah; Bonder, Marc Jan

effects of the interactions between tissues and probes using BLUP (Best Linear Unbiased Prediction) linear models correcting for gender, which were subsequently used in a finite mixture model to detect DE genes in each tissue. This approach evades the multiple-testing problem and is able to detect...

Materials analysis using x-ray linear attenuation coefficient measurements at four photon energies

International Nuclear Information System (INIS)

Midgley, S M

2005-01-01

The analytical properties of an accurate parameterization scheme for the x-ray linear attenuation coefficient are examined. The parameterization utilizes an additive combination of N compositional- and energy-dependent coefficients. The former were derived from a parameterization of elemental cross-sections using a polynomial in atomic number. The compositional-dependent coefficients are referred to as the mixture parameters, representing the electron density and higher order statistical moments describing elemental distribution. Additivity is an important property of the parameterization, allowing measured x-ray linear attenuation coefficients to be written as linear simultaneous equations, and then solved for the unknown coefficients. The energy-dependent coefficients can be determined by calibration from measurements with materials of known composition. The inverse problem may be utilized for materials analysis, whereby the simultaneous equations represent multi-energy linear attenuation coefficient measurements, and are solved for the mixture parameters. For in vivo studies, the choice of measurement energies is restricted to the diagnostic region (approximately 20 keV to 150 keV), where the parameterization requires N ≥ 4 energies. We identify a mathematical pathology that must be overcome in order to solve the inverse problem in this energy regime. An iterative inversion strategy is presented for materials analysis using four or more measurements, and then tested against real data obtained at energies 32 keV to 66 keV. The results demonstrate that it is possible to recover the electron density to within ±4% and fourth mixture parameter. It is also a key finding that the second and third mixture parameters cannot be recovered, as they are of minor importance in the parameterization at diagnostic x-ray energies

Photo polymerization-induced vertical phase separation and homeotropic alignment in liquid crystal and polymer mixtures

International Nuclear Information System (INIS)

Kang, Hyo; Joo, Sangwoo; Kang, Daeseung

2012-01-01

We presented a novel method for the homeotropic alignment of LC by using the irradiation of UV light on the LC/NOA65 mixture cell, in which the photo-initiated-polymerization-induced phase separation lowers the surface energy. When the amount of polymer content is sufficiently small, the gravel and network patterns were formed at the substrates via the vertical phase separation. We found that surface roughness plays an important role in the formation of the homeotropic alignment of LC. We also observed the alignment transition of the cells by varying the mixing ratio of LC/NOA65 or the UV radiation time. Furthermore, the present proposed method has great potential for application in display devices. For decades, studies on the alignment of liquid crystal (LC) molecules have been of significant interest due to their immediate applications for display devices and the intriguing physiochemical properties they exhibit at the surface of mixtures. Usually, homeotropic (or vertical) alignment, in which the long axes of the LC molecules are oriented in a direction perpendicular to the surface, is achieved by using surfactants such as lecithin, silanes or polyimide. Recently homeotropic alignment of liquid crystal molecules was achieved by irradiating photosensitive polymers, by doping nanoparticles into LC, by utilizing nano/micro patterns, or by incorporating self-assembled monolayers (SAMs). However, a clear understanding about the alignment mechanism is still elusive. In this paper, we report a novel method for homeotropic alignment of LC by utilizing the phase separation of LC/polymer mixtures

Molecular electronics--resonant transport through single molecules.

Science.gov (United States)

Lörtscher, Emanuel; Riel, Heike

2010-01-01

The mechanically controllable break-junction technique (MCBJ) enables us to investigate charge transport through an individually contacted and addressed molecule in ultra-high vacuum (UHV) environment at variable temperature ranging from room temperature down to 4 K. Using a statistical measurement and analysis approach, we acquire current-voltage (I-V) characteristics during the repeated formation, manipulation, and breaking of a molecular junction. At low temperatures, voltages accessing the first molecular orbitals in resonance can be applied, providing spectroscopic information about the junction's energy landscape, in particular about the molecular level alignment in respect to the Fermi energy of the electrodes. Thereby, we can investigate the non-linear transport properties of various types of functional molecules and explore their potential use as functional building blocks for future nano-electronics. An example will be given by the reversible and controllable switching between two distinct conductive states of a single molecule. As a proof-of-principle for functional molecular devices, a single-molecule memory element will be demonstrated.

Satellite bands of the RbCs molecule in the range of highly excited states

Energy Technology Data Exchange (ETDEWEB)

Rakić, Mario; Beuc, Robert; Skenderović, Hrvoje, E-mail: hrvoje@ifs.hr [Institute of Physics, Bijenička cesta 46, Zagreb 10000 (Croatia); Bouloufa-Maafa, Nadia; Dulieu, Olivier; Vexiau, Romain [Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, Bât. 505, Campus d’Orsay, Orsay Cedex 91405 (France); Pichler, Goran [Physics Department, Kuwait University, PO Box 5969, Safat—13060 (Kuwait)

2016-05-28

We report on the observation of three RbCs satellite bands in the blue and green ranges of the visible spectrum. Absorption measurements are performed using all-sapphire cell filled with a mixture of Rb and Cs. We compare high resolution absorption spectrum of Rb-Cs vapor mixture with pure Rb and Cs vapor spectra from the literature. After detailed analysis, the new satellite bands of RbCs molecule at 418.3 nm, 468.3, and 527.5 nm are identified. The origin of these bands is discussed by direct comparison with difference potentials derived from quantum chemistry calculations of RbCs potential energy curves. These bands originate from the lower Rydberg states of the RbCs molecule. This study thus provides further insight into photoassociation of lower Rydberg molecular states, approximately between Cs(7s) + Rb(5s) and Cs(6s) + Rb(6p) asymptotes, in ultracold gases.

Molecular Dynamics Simulations of Carbon Dioxide, Methane, and Their Mixture in Montmorillonite Clay Hydrates

KAUST Repository

Kadoura, Ahmad Salim; Nair, Arun Kumar Narayanan; Sun, Shuyu

2016-01-01

Molecular dynamics simulations were carried out to study the structural and transport properties of carbon dioxide, methane, and their mixture at 298.15 K in Na-montmorillonite clay in the presence of water. The simulations show that, the self-diffusion coefficients of pure CO2 and CH4 molecules in the interlayers of Na-montmorillonite decrease as their loading increases, possibly because of steric hindrance. The diffusion of CO2 in the interlayers of Na-montmorillonite, at constant loading of CO2, is not significantly affected by CH4 for the investigated CO2/CH4 mixture compositions. We attribute this to the preferential adsorption of CO2 over CH4 in Na-montmorillonite. While the presence of adsorbed CO2 molecules, at constant loading of CH4, very significantly reduces the self-diffusion coefficients of CH4, and relatively larger decrease in those diffusion coefficients are obtained at higher loadings. The preferential adsorption of CO2 molecules to the clay surface screens those possible attractive surface sites for CH4. The competition between screening and steric effects leads to a very slight decrease in the diffusion coefficients of CH4 molecules at low CO2 loadings. The steric hindrance effect, however, becomes much more significant at higher CO2 loadings and the diffusion coefficients of methane molecules significantly decrease. Our simulations also indicate that, similar effects of water on both carbon dioxide and methane, increase with increasing water concentration, at constant loadings of CO2 and CH4 in the interlayers of Na-montmorillonite. Our results could be useful, because of the significance of shale gas exploitation and carbon dioxide storage.

Molecular Dynamics Simulations of Carbon Dioxide, Methane, and Their Mixture in Montmorillonite Clay Hydrates

KAUST Repository

Kadoura, Ahmad Salim

2016-05-26

Molecular dynamics simulations were carried out to study the structural and transport properties of carbon dioxide, methane, and their mixture at 298.15 K in Na-montmorillonite clay in the presence of water. The simulations show that, the self-diffusion coefficients of pure CO2 and CH4 molecules in the interlayers of Na-montmorillonite decrease as their loading increases, possibly because of steric hindrance. The diffusion of CO2 in the interlayers of Na-montmorillonite, at constant loading of CO2, is not significantly affected by CH4 for the investigated CO2/CH4 mixture compositions. We attribute this to the preferential adsorption of CO2 over CH4 in Na-montmorillonite. While the presence of adsorbed CO2 molecules, at constant loading of CH4, very significantly reduces the self-diffusion coefficients of CH4, and relatively larger decrease in those diffusion coefficients are obtained at higher loadings. The preferential adsorption of CO2 molecules to the clay surface screens those possible attractive surface sites for CH4. The competition between screening and steric effects leads to a very slight decrease in the diffusion coefficients of CH4 molecules at low CO2 loadings. The steric hindrance effect, however, becomes much more significant at higher CO2 loadings and the diffusion coefficients of methane molecules significantly decrease. Our simulations also indicate that, similar effects of water on both carbon dioxide and methane, increase with increasing water concentration, at constant loadings of CO2 and CH4 in the interlayers of Na-montmorillonite. Our results could be useful, because of the significance of shale gas exploitation and carbon dioxide storage.

Thermodynamics of organic mixtures containing amines. VIII. Systems with quinoline

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, Juan Antonio [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain)], E-mail: jagl@termo.uva.es; Domanska, Urszula; Zawadzki, Maciej [Physical Chemistry Division, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw (Poland)

2008-08-15

(Solid + liquid) equilibrium temperatures for mixtures containing quinoline and 1-dodecanol, 1-hexadecanol, or 1-octadecanol have been measured using a dynamic method. (Quinoline + benzene, +alkane, or +1-alkanol) systems were investigated using DISQUAC. The corresponding interaction parameters are reported. The model yields a good representation of molar excess Gibbs free energies, G{sup E}, molar excess enthalpies, H{sup E}, and of the (solid + liquid) equilibria, SLE. Interactional and structural effects were analysed comparing H{sup E} and the molar excess internal energy at constant volume, U{sub V}{sup E}. It was encountered that structural effects are very important in systems involving alkanes or 1-alkanols. Interactions between amine molecules are stronger in mixtures with quinoline than in those containing pyridine, which was ascribed to the higher polarizability of quinoline.

Pairing and condensation in a resonant Bose-Fermi mixture

International Nuclear Information System (INIS)

Fratini, Elisa; Pieri, Pierbiagio

2010-01-01

We study by diagrammatic means a Bose-Fermi mixture, with boson-fermion coupling tuned by a Fano-Feshbach resonance. For increasing coupling, the growing boson-fermion pairing correlations progressively reduce the boson condensation temperature and make it eventually vanish at a critical coupling. Such quantum critical point depends very weakly on the population imbalance and, for vanishing boson densities, coincides with that found for the polaron-molecule transition in a strongly imbalanced Fermi gas, thus bridging two quite distinct physical systems.

Quasiparticle Lifetime in Ultracold Fermionic Mixtures with Density and Mass Imbalance

DEFF Research Database (Denmark)

Lan, Zhihao; Bruun, Georg; Lobo, Carlos

2013-01-01

We show that atomic Fermi mixtures with density and mass imbalance exhibit a rich diversity of scaling laws for the quasiparticle decay rate beyond the quadratic energy and temperature dependence of conventional Fermi liquids. For certain densities and mass ratios, the decay rate is linear, whereas...

A new hybrid double divisor ratio spectra method for the analysis of ternary mixtures

Science.gov (United States)

Youssef, Rasha M.; Maher, Hadir M.

2008-10-01

A new spectrophotometric method was developed for the simultaneous determination of ternary mixtures, without prior separation steps. This method is based on convolution of the double divisor ratio spectra, obtained by dividing the absorption spectrum of the ternary mixture by a standard spectrum of two of the three compounds in the mixture, using combined trigonometric Fourier functions. The magnitude of the Fourier function coefficients, at either maximum or minimum points, is related to the concentration of each drug in the mixture. The mathematical explanation of the procedure is illustrated. The method was applied for the assay of a model mixture consisting of isoniazid (ISN), rifampicin (RIF) and pyrazinamide (PYZ) in synthetic mixtures, commercial tablets and human urine samples. The developed method was compared with the double divisor ratio spectra derivative method (DDRD) and derivative ratio spectra-zero-crossing method (DRSZ). Linearity, validation, accuracy, precision, limits of detection, limits of quantitation, and other aspects of analytical validation are included in the text.

Measurement of the figure of merit M for 1-C3F6/SF6 mixtures

DEFF Research Database (Denmark)

Christensen, Jørn Erik Berril; McAllister, Iain Wilson

1997-01-01

High precision measurements of the linear part of the Paschen curve are reported for 1-C3F6/SF6 mixtures. From these measurements, values for the pressure-reduced limiting electric field strength (E/p)lim and the associated figure of merit M are derived. These two parameters can be used to charac......High precision measurements of the linear part of the Paschen curve are reported for 1-C3F6/SF6 mixtures. From these measurements, values for the pressure-reduced limiting electric field strength (E/p)lim and the associated figure of merit M are derived. These two parameters can be used...

Molecular Dynamics Simulations for Loading-Dependent Diffusion of CO2, SO2, CH4, and Their Binary Mixtures in ZIF-10: The Role of Hydrogen Bond.

Science.gov (United States)

Li, Li; Yang, Deshuai; Fisher, Trevor R; Qiao, Qi; Yang, Zhen; Hu, Na; Chen, Xiangshu; Huang, Liangliang

2017-10-24

The loading-dependent diffusion behavior of CH 4 , CO 2 , SO 2 , and their binary mixtures in ZIF-10 has been investigated in detail by using classical molecular dynamics simulations. Our simulation results demonstrate that the self-diffusion coefficient D i of CH 4 molecules decreases sharply and monotonically with the loading while those of both CO 2 and SO 2 molecules initially display a slight increase at low uptakes and follow a slow decrease at high uptakes. Accordingly, the interaction energies between CH 4 molecules and ZIF-10 remain nearly constant regardless of the loading due to the absence of hydrogen bonds (HBs), while the interaction energies between CO 2 (or SO 2 ) and ZIF-10 decease rapidly with the loading, especially at small amounts of gas molecules. Such different loading-dependent diffusion and interaction mechanisms can be attributed to the relevant HB behavior between gas molecules and ZIF-10. At low loadings, both the number and strength of HBs between CO 2 (or SO 2 ) molecules and ZIF-10 decrease obviously as the loading increases, which is responsible for the slight increase of their diffusion coefficients. However, at high loadings, their HB strength increases with the loading. Similar loading-dependent phenomena of diffusion, interaction, and HB behavior can be observed for CH 4, CO 2 , and SO 2 binary mixtures in ZIF-10, only associated with some HB competition between CO 2 and SO 2 molecules in the case of the CO 2 /SO 2 mixture.

Emision of Cl2* molecules in a barrier discharge

International Nuclear Information System (INIS)

Avdeev, S M; Erofeev, M V; Sosnin, E A; Tarasenko, V F

2008-01-01

The energy and spectral parameters of emission of a barrier discharge in chlorine and its mixtures with inert gases are studied experimentally. The barrier discharge in chlorine was homogeneous at pressures up to ∼9 Torr and its spectrum contained the 3 Π 2g → 3 Π 2u , 3 Π 2g → 3 Σ 2u + and 1 Σ u + → 1 Σ g + bands of Cl 2 * molecules. After the addition of an inert gas, the 257.8-nm 3 Π 2g → 3 Π 2u band made the main contribution to the spectrum. The maximum efficiency and power of the Cl 2 excilamp were obtained for the chlorine-argon mixture and amounted to 0.7% and 1.3 W, respectively. (laser applications and other topics in quantum electronics)

Thermodynamic study of (heptane + amine) mixtures. II. Excess and partial molar volumes at 298.15 K

International Nuclear Information System (INIS)

Lepori, Luciano; Gianni, Paolo; Spanedda, Andrea; Matteoli, Enrico

2011-01-01

Research highlights: → Excess and partial molar volumes of primary (amines + heptane) mixtures. → Excess volumes are positive for small size amines and decrease as the size increases. → Group contributions to predict the partial molar volumes of amines in heptane. → The void volume is larger for branched than for linear amines in heptane. - Abstract: Excess molar volumes V E at 298.15 K were determined by means of a vibrating tube densimeter for binary mixtures of heptane + primary n-alkyl (C 3 to C 10 ) and branched amines (iso-propyl-, iso-, sec-, and tert-butyl-, iso-, tert-pentyl-, and pentan-3-amine) in the whole composition range. The apparent molar volumes of solid dodecyl- and tetradecylamine in heptane dilute solution were also determined. The V E values were found positive for mixtures involving C 3 to C 8 linear amines, with V E decreasing with chain lengthening. Heptane + nonyl and decylamine showed s-shaped, markedly asymmetric, curves. Mixtures with branched C 3 to C 5 amines displayed positive V E 's larger than those observed in the mixtures of the corresponding linear isomers. Partial molar volumes V o at infinite dilution in heptane were evaluated for the examined amines and compared with those of alkanes and alkanols taken from the literature. An additivity scheme, based on the intrinsic volume approach, was applied to estimate group (CH 3 , CH 2 , CH, C, NH 2 , and OH) contributions to V o . The effect of branching on V o and the limiting slope of the apparent excess molar volumes were evaluated and discussed in terms of solute-solvent and solute-solute interactions.

Measuring pair-wise molecular interactions in a complex mixture

Science.gov (United States)

Chakraborty, Krishnendu; Varma, Manoj M.; Venkatapathi, Murugesan

2016-03-01

Complex biological samples such as serum contain thousands of proteins and other molecules spanning up to 13 orders of magnitude in concentration. Present measurement techniques do not permit the analysis of all pair-wise interactions between the components of such a complex mixture to a given target molecule. In this work we explore the use of nanoparticle tags which encode the identity of the molecule to obtain the statistical distribution of pair-wise interactions using their Localized Surface Plasmon Resonance (LSPR) signals. The nanoparticle tags are chosen such that the binding between two molecules conjugated to the respective nanoparticle tags can be recognized by the coupling of their LSPR signals. This numerical simulation is done by DDA to investigate this approach using a reduced system consisting of three nanoparticles (a gold ellipsoid with aspect ratio 2.5 and short axis 16 nm, and two silver ellipsoids with aspect ratios 3 and 2 and short axes 8 nm and 10 nm respectively) and the set of all possible dimers formed between them. Incident light was circularly polarized and all possible particle and dimer orientations were considered. We observed that minimum peak separation between two spectra is 5 nm while maximum is 184nm.

A Linear Tetranuclear Dysprosium(III) Compound Showing Single-Molecule Magnet Behavior

Energy Technology Data Exchange (ETDEWEB)

Ke, Hongshan; Xu, Gong Feng; Guo, Yun-Nan; Gamez, Patrick; Beavers, Christine M; Teat, Simon J; Tang, Jinkui

2010-04-20

Although magnetic measurements reveal a single-relaxation time for a linear tetranuclear Dy(III) compound, the wide distribution of the relaxation time observed clearly suggests the presence of two slightly different anisotropic centres, therefore opening new avenues for investigating the relaxation dynamics of lanthanide aggregates.

Ultrasonic and viscosimetric studies of samarium laurate in benzene-dimethylsulfoxide mixtures

International Nuclear Information System (INIS)

Mehrotra, K.N.; Anis, M.

1995-01-01

Ultrasonic and viscosity measurements of samarium laurate in benzene-DMSO mixtures of different compositions (7:3 and 1:1 V/V) have been used to determine the critical micelle concentration (CMC), soap-solvent interaction, and various acoustic parameters of the system. The values of critical micelle concentration increase with increasing amount of DMSO in the solvent mixtures. The viscosity results have been explained on the basis of equations proposed by Einstein, Vand. Moulik, and Jones-Dole. The values of CMC for samarium laurate obtained from the viscosity measurements are in agreement with the results obtained from ultrasonic measurements. The results show that the soap molecules do not aggregate appreciably below CMC there is a marked change in the aggregation behaviour at CMC. (author)

Mixture

Directory of Open Access Journals (Sweden)

Silva-Aguilar Martín

2011-01-01

Full Text Available Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity.

On Two Mixture-Based Clustering Approaches Used in Modeling an Insurance Portfolio

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Tatjana Miljkovic

2018-05-01

Full Text Available We review two complementary mixture-based clustering approaches for modeling unobserved heterogeneity in an insurance portfolio: the generalized linear mixed cluster-weighted model (CWM and mixture-based clustering for an ordered stereotype model (OSM. The latter is for modeling of ordinal variables, and the former is for modeling losses as a function of mixed-type of covariates. The article extends the idea of mixture modeling to a multivariate classification for the purpose of testing unobserved heterogeneity in an insurance portfolio. The application of both methods is illustrated on a well-known French automobile portfolio, in which the model fitting is performed using the expectation-maximization (EM algorithm. Our findings show that these mixture-based clustering methods can be used to further test unobserved heterogeneity in an insurance portfolio and as such may be considered in insurance pricing, underwriting, and risk management.

Adiabatic Field-Free Alignment of Asymmetric Top Molecules with an Optical Centrifuge.

Science.gov (United States)

Korobenko, A; Milner, V

2016-05-06

We use an optical centrifuge to align asymmetric top SO_{2} molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines the sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment that persists after the molecules are released from the centrifuge. The periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 deg, permanent field-free alignment offers new ways of controlling molecules with laser light.

A quantum mechanical strategy to investigate the structure of liquids: the cases of acetonitrile, formamide, and their mixture.

Science.gov (United States)

Mennucci, Benedetta; da Silva, Clarissa O

2008-06-05

A computational strategy based on quantum mechanical (QM) calculations and continuum solvation models is used to investigate the structure of liquids (either neat liquids or mixtures). The strategy is based on the comparison of calculated and experimental spectroscopic properties (IR-Raman vibrational frequencies and Raman intensities). In particular, neat formamide, neat acetonitrile, and their equimolar mixture are studied comparing isolated and solvated clusters of different nature and size. In all cases, the study seems to indicate that liquids, even when strongly associated, can be effectively modeled in terms of a shell-like system in which clusters of strongly interacting molecules (the microenvironments) are solvated by a polarizable macroenvironment represented by the rest of the molecules. Only taking into proper account both these effects can a correct picture of the liquid structure be achieved.

Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

Energy Technology Data Exchange (ETDEWEB)

Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain)

2015-09-14

We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related

Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

International Nuclear Information System (INIS)

Martínez-Ruiz, F. J.; Blas, F. J.; Moreno-Ventas Bravo, A. I.

2015-01-01

We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ 11 = σ 22 , with the same dispersive energy between like species, ϵ 11 = ϵ 22 , but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r c and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r c is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the

The ‘ideal selectivity’ vs ‘true selectivity’ for permeation of gas mixture in nanoporous membranes

Science.gov (United States)

He, Zhou; Wang, Kean

2018-03-01

In this study, we proposed and validated a novel and non-destructive experimental technology for measuring the permeation of binary gas mixture in nanoporous membranes. The traditional time lag rig was modified to examine the permeation characteristics of each gas component as well as that of the binary gas mixtures. The difference in boiling points of each species were explored. Binary gas mixtures of CO2/He were permeated through the nanoporous carbon molecular sieve membrane (CMSM). The results showed that, due to the strong interaction among different molecules and with the porous network of the membrane, the measured perm-selectivity or ‘true selectivity’ of a binary mixture can significantly deviate from the ‘ideal selectivity’ calculated form the permeation flux of each pure species, and this deviation is a complicated function of the molecular properties and operation conditions.

Densities and viscosities of binary and ternary mixtures of cyclohexanone, 1,4-dioxane and isooctane from T = (288.15 to 313.15) K

International Nuclear Information System (INIS)

Rafiee, Hamid Reza; Ranjbar, Shahram; Poursalman, Fariborz

2012-01-01

Graphical abstract: For binary and ternary mixtures of the following liquids the densities and viscosities have been determined at several temperatures and over the entire range of composition. Also the Δη and excess molar volumes for binary mixtures determined and have been fitted to the Redlich–Kister equation. The interaction parameters, G 12 in the Grunberg–Nissan equation have been found to be negative for all binary mixtures which indicates decreasing the interaction between unlike molecules. Highlights: ► Experimental data for viscosity and density of binary and ternary mixtures reported. ► The considered solvents are Cyclohexanone, 1,4-Dioxane and Isooctane. ► Temperature ranges from 288.15 to 313.15 K and entire range of composition is considered. ► G 12 , in Grunberg–Nissan equation was negative in all binary mixtures at all temperatures. ► V E and Δη for binary mixtures have been fitted to Redlich–Kister equation. - Abstract: Densities and viscosities of binary and ternary mixtures of cyclohexanone, 1,4-dioxane and isooctane have been measured at temperatures from 288.15 K to 313.15 K and over the entire composition range, under atmospheric pressure. From these binary data, the excess molar volumes have been determined and then fitted to Redlich–Kister equation to determine the appropriate coefficients. This work also provides a test of the Grunberg and Nissan equation for correlation the dynamic viscosities of binary mixtures with mole fractions. The interaction parameters for this equation, G 12 were negative for all binary mixtures at different temperatures over entire range of composition which attributed to decreasing the strength of interaction between unlike molecules in mixture.

Assessment of competition and yield advantage in addition series of barley variety mixtures

Directory of Open Access Journals (Sweden)

Kari Jokinen

1991-09-01

Full Text Available In an addition series experiment the competition between three barley varieties (Agneta, Arra and Porno and the yield performance of mixtures were evaluated. Also two levels of nitrogen fertilization (50 and 100 kgN/ha were applied. Two approaches (the replacement series and the linear regression equation were used to analyse the competitive relationship based on grain yields in two-component mixtures. In three component mixtures the replacement series approach was applied. Both methods showed a similar dominance order of the varieties with Arra always being dominant and Agneta subordinate. The relationship between varieties was independent of the number of varieties in the mixture. Increase in available nitrogen strengthened the competitiveness of Arra especially in the dense, two-variety mixtures. Some mixtures over yielded but the differences were not statistically significant. The yield advantage based on relative yield total or on the ratio of actual and expected yield was greatest when the density and nitrogen fertilization were low and especially when one component in the mixture was a rather low yielding variety (Agneta. The land equivalent ratios (LER (the reference pure culture yield was the maximum yield of each variety were close to one, suggesting that under optimal growing conditions the yield advantage of barley varietal mixtures is marginal.

Laminar Flame Velocity and Temperature Exponent of Diluted DME-Air Mixture

Science.gov (United States)

Naseer Mohammed, Abdul; Anwar, Muzammil; Juhany, Khalid A.; Mohammad, Akram

2017-03-01

In this paper, the laminar flame velocity and temperature exponent diluted dimethyl ether (DME) air mixtures are reported. Laminar premixed mixture of DME-air with volumetric dilutions of carbon dioxides (CO2) and nitrogen (N2) are considered. Experiments were conducted using a preheated mesoscale high aspect-ratio diverging channel with inlet dimensions of 25 mm × 2 mm. In this method, flame velocities are extracted from planar flames that were stabilized near adiabatic conditions inside the channel. The flame velocities are then plotted against the ratio of mixture temperature and the initial reference temperature. A non-linear power law regression is observed suitable. This regression analysis gives the laminar flame velocity at the initial reference temperature and temperature exponent. Decrease in the laminar flame velocity and increase in temperature exponent is observed for CO2 and N2 diluted mixtures. The addition of CO2 has profound influence when compared to N2 addition on both flame velocity and temperature exponent. Numerical prediction of the similar mixture using a detailed reaction mechanism is obtained. The computational mechanism predicts higher magnitudes for laminar flame velocity and smaller magnitudes of temperature exponent compared to experimental data.

Quantum Monte Carlo for vibrating molecules

International Nuclear Information System (INIS)

Brown, W.R.; Lawrence Berkeley National Lab., CA

1996-08-01

Quantum Monte Carlo (QMC) has successfully computed the total electronic energies of atoms and molecules. The main goal of this work is to use correlation function quantum Monte Carlo (CFQMC) to compute the vibrational state energies of molecules given a potential energy surface (PES). In CFQMC, an ensemble of random walkers simulate the diffusion and branching processes of the imaginary-time time dependent Schroedinger equation in order to evaluate the matrix elements. The program QMCVIB was written to perform multi-state VMC and CFQMC calculations and employed for several calculations of the H 2 O and C 3 vibrational states, using 7 PES's, 3 trial wavefunction forms, two methods of non-linear basis function parameter optimization, and on both serial and parallel computers. In order to construct accurate trial wavefunctions different wavefunctions forms were required for H 2 O and C 3 . In order to construct accurate trial wavefunctions for C 3 , the non-linear parameters were optimized with respect to the sum of the energies of several low-lying vibrational states. In order to stabilize the statistical error estimates for C 3 the Monte Carlo data was collected into blocks. Accurate vibrational state energies were computed using both serial and parallel QMCVIB programs. Comparison of vibrational state energies computed from the three C 3 PES's suggested that a non-linear equilibrium geometry PES is the most accurate and that discrete potential representations may be used to conveniently determine vibrational state energies

Differential effects of Th1, monocyte/macrophage and Th2 cytokine mixtures on early gene expression for molecules associated with metabolism, signaling and regulation in central nervous system mixed glial cell cultures

Directory of Open Access Journals (Sweden)

Studzinski Diane

2009-01-01

Full Text Available Abstract Background Cytokines secreted by immune cells and activated glia play central roles in both the pathogenesis of and protection from damage to the central nervous system (CNS in multiple sclerosis (MS. Methods We have used gene array analysis to identify the initial direct effects of cytokines on CNS glia by comparing changes in early gene expression in CNS glial cultures treated for 6 hours with cytokines typical of those secreted by Th1 and Th2 lymphocytes and monocyte/macrophages (M/M. Results In two previous papers, we summarized effects of these cytokines on immune-related molecules, and on neural and glial related proteins, including neurotrophins, growth factors and structural proteins. In this paper, we present the effects of the cytokines on molecules involved in metabolism, signaling and regulatory mechanisms in CNS glia. Many of the changes in gene expression were similar to those seen in ischemic preconditioning and in early inflammatory lesions in experimental autoimmune encephalomyelitis (EAE, related to ion homeostasis, mitochondrial function, neurotransmission, vitamin D metabolism and a variety of transcription factors and signaling pathways. Among the most prominent changes, all three cytokine mixtures markedly downregulated the dopamine D3 receptor, while Th1 and Th2 cytokines downregulated neuropeptide Y receptor 5. An unexpected finding was the large number of changes related to lipid metabolism, including several suggesting a switch from diacylglycerol to phosphatidyl inositol mediated signaling pathways. Using QRT-PCR we validated the results for regulation of genes for iNOS, arginase and P glycoprotein/multi-drug resistance protein 1 (MDR1 seen at 6 hours with microarray. Conclusion Each of the three cytokine mixtures differentially regulated gene expression related to metabolism and signaling that may play roles in the pathogenesis of MS, most notably with regard to mitochondrial function and neurotransmitter

Boltzmann equation analysis of electron-molecule collision cross sections in water vapor and ammonia

International Nuclear Information System (INIS)

Yousfi, M.; Benabdessadok, M.D.

1996-01-01

Sets of electron-molecule collision cross sections for H 2 O and NH 3 have been determined from a classical technique of electron swarm parameter unfolding. This deconvolution method is based on a simplex algorithm using a powerful multiterm Boltzmann equation analysis established in the framework of the classical hydrodynamic approximation. It is well adapted for the simulation of the different classes of swarm experiments (i.e., time resolved, time of flight, and steady state experiments). The sets of collision cross sections that exist in the literature are reviewed and analyzed. Fitted sets of cross sections are determined for H 2 O and NH 3 which exhibit features characteristic of polar molecules such as high rotational excitation collision cross sections. The hydrodynamic swarm parameters (i.e., drift velocity, longitudinal and transverse diffusion coefficients, ionization and attachment coefficients) calculated from the fitted sets are in excellent agreement with the measured ones. These sets are finally used to calculate the transport and reaction coefficients needed for discharge modeling in two cases of typical gas mixtures for which experimental swarm data are very sparse or nonexistent (i.e., flue gas mixtures and gas mixtures for rf plasma surface treatment). copyright 1996 American Institute of Physics

Solvatochromism of naringenin in aqueous alcoholic mixtures

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Faraji Mohammad

2016-01-01

Full Text Available The spectral change of naringenin was studied by Uv-vis spectrophotometric method in binary mixtures of water with methanol, ethanol and 1-propanol at 25°C. The effect of solvent was investigated by analysis of electron transition energy at the maximum absorption wavelength as a function of Kamlet and Taft parameters of mixtures by means of linear solvation energy relationships. The nonlinear response of solvatochromism was explained based on solute-solvent and solvent-solvent interactions. The possible preferential solvation of naringenin by each of solvents was studied through a modified preferential solvation model which considers the hydrogen bonding interactions between the prior solvents due to solvent-solvent interactions. The preferential solvation parameters and local mole fraction distribution around the solute were calculated. Results indicate that naringenin prefers to be more solvated by the complex solvating species and organic solvents than water.

Photoexcitation circular dichroism in chiral molecules

Science.gov (United States)

Beaulieu, S.; Comby, A.; Descamps, D.; Fabre, B.; Garcia, G. A.; Géneaux, R.; Harvey, A. G.; Légaré, F.; Mašín, Z.; Nahon, L.; Ordonez, A. F.; Petit, S.; Pons, B.; Mairesse, Y.; Smirnova, O.; Blanchet, V.

2018-05-01

Chiral effects appear in a wide variety of natural phenomena and are of fundamental importance in science, from particle physics to metamaterials. The standard technique of chiral discrimination—photoabsorption circular dichroism—relies on the magnetic properties of a chiral medium and yields an extremely weak chiral response. Here, we propose and demonstrate an orders of magnitude more sensitive type of circular dichroism in neutral molecules: photoexcitation circular dichroism. This technique does not rely on weak magnetic effects, but takes advantage of the coherent helical motion of bound electrons excited by ultrashort circularly polarized light. It results in an ultrafast chiral response and the efficient excitation of a macroscopic chiral density in an initially isotropic ensemble of randomly oriented chiral molecules. We probe this excitation using linearly polarized laser pulses, without the aid of further chiral interactions. Our time-resolved study of vibronic chiral dynamics opens a way to the efficient initiation, control and monitoring of chiral chemical change in neutral molecules at the level of electrons.

A Linear Gradient Theory Model for Calculating Interfacial Tensions of Mixtures

DEFF Research Database (Denmark)

Zou, You-Xiang; Stenby, Erling Halfdan

1996-01-01

excellent agreement between the predicted and experimental IFTs at high and moderate levels of IFTs, while the agreement is reasonably accurate in the near-critical region as the used equations of state reveal classical scaling behavior. To predict accurately low IFTs (sigma ... with proper scaling behavior at the critical point is at least required.Key words: linear gradient theory; interfacial tension; equation of state; influence parameter; density profile....

Beyond GLMs: a generative mixture modeling approach to neural system identification.

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Lucas Theis

Full Text Available Generalized linear models (GLMs represent a popular choice for the probabilistic characterization of neural spike responses. While GLMs are attractive for their computational tractability, they also impose strong assumptions and thus only allow for a limited range of stimulus-response relationships to be discovered. Alternative approaches exist that make only very weak assumptions but scale poorly to high-dimensional stimulus spaces. Here we seek an approach which can gracefully interpolate between the two extremes. We extend two frequently used special cases of the GLM-a linear and a quadratic model-by assuming that the spike-triggered and non-spike-triggered distributions can be adequately represented using Gaussian mixtures. Because we derive the model from a generative perspective, its components are easy to interpret as they correspond to, for example, the spike-triggered distribution and the interspike interval distribution. The model is able to capture complex dependencies on high-dimensional stimuli with far fewer parameters than other approaches such as histogram-based methods. The added flexibility comes at the cost of a non-concave log-likelihood. We show that in practice this does not have to be an issue and the mixture-based model is able to outperform generalized linear and quadratic models.

Viscosity of Associated Mixtures Approximated by the Grunberg-Nissan Model

Science.gov (United States)

Marczak, W.; Adamczyk, N.; Łężniak, M.

2012-04-01

Previous experiments demonstrated that microheterogeneities occur in liquid systems (2-methylpyridine or 2,6-dimethylpyridine) + water. They are most probably due to the association of the hydrates through hydrogen bonds between water molecules. Substitution of methanol for water causes that the mixtures become homogenous. The results of viscometric studies reported in this study confirmed that the molecular clusters in aqueous solutions are much larger than the complexes occurring in the methanolic systems. Taking into consideration "kinetic entities" rather than monomeric molecules, the dependence of viscosity on concentration and temperature have been satisfactorily approximated by the Grunberg-Nissan relation with two adjustable coefficients. The kinetic entities were trimers of water, dimers of methanol, and monomeric amines. The same approach proved to be valid for the activation energy of viscous flow as well.

Structural, Spectroscopic (FT-IR, Raman and NMR, Non-linear Optical (NLO, HOMO-LUMO and Theoretical (DFT/CAM-B3LYP Analyses of N-Benzyloxycarbonyloxy-5-Norbornene-2,3-Dicarboximide Molecule

Directory of Open Access Journals (Sweden)

Nuri ÖZTÜRK

2018-02-01

Full Text Available The experimental spectroscopic investigation of N-benzyloxycarbonyloxy-5-norbornene-2,3-dicarboximide (C17H15NO5 molecule has been done using 1H and 13C NMR chemical shifts, FT-IR and Raman spectroscopies. Conformational forms have been determined depending on orientation of N-benzyloxycarbonyloxy and 5-norbornene-2,3-dicarboximide (NDI groups of the title compound. The structural geometric optimizations, vibrational wavenumbers, NMR chemical shifts (in vacuum and chloroform and HOMO-LUMO analyses for all conformers of the title molecule have been done with DFT/CAM-B3LYP method at the 6-311++G(d,p basis set. Additionally, based on the calculated HOMO and LUMO energy values, some molecular properties such as ionization potential (I, electron affinity (A, electronegativity (χ, chemical hardness (h, chemical softness (z, chemical potential (μ and electrophilicity index (w parameters are determined for all conformers. The non-linear optical (NLO properties have been studied for the title molecule. We can say that the experimental spectral data are in accordance with calculated values.

The largest molecules in space

International Nuclear Information System (INIS)

Greenberg, J.M.

1983-01-01

The bulk of complex molecules in the space between the stars is shown to be in the small frozen particles of interstellar dust. Each dust grain typically contains some 10 9 atoms of oxygen, carbon and nitrogen in an amorphous molecular mixture. As a result of chemical processing of the particles by ultraviolet photons over times spanning proportional10 8 -10 9 years a substantial portion of each dust grain is converted into complex organic molecules whose maximum molecular weight is limited only by the size of the grain. Laboratory studies of evolution of analog grain materials shows that molecular weights of the order of 500 are readily created and that there is an excellent probability of much more complex molecules being produced. The organic dust component constitutes about one tenth of a percent of the total mass of the Milky Way and far outweighs any estimates of the total mass of all the planets. A planet like the earth is continually accreting matter from space and there was a high probability that in the first five hundred million years after its crust formed it passed through several dark clouds and accreted from a hundred million to ten thousand million tonnes of the organic material of the interstellar dust during each passage. It is suggested that this rain of material could have provided the molecular templates for the origin of life. (orig.)

Velocity of large bubble in liquid-solid mixture in a vertical tube

International Nuclear Information System (INIS)

Hamaguchi, H.; Sakaguchi, T.

1995-01-01

The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V o in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V * (=V/V o ), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V * decreases linearly against the volumetric solid fraction ε of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V * and ε is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid

Velocity of large bubble in liquid-solid mixture in a vertical tube

Energy Technology Data Exchange (ETDEWEB)

Hamaguchi, H.; Sakaguchi, T. [Kobe Univ., Kobe (Japan)

1995-09-01

The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V{sub o} in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V{sup *}(=V/V{sub o}), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V{sup *} decreases linearly against the volumetric solid fraction {epsilon} of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V{sup *} and {epsilon} is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid.

Urea and deuterium mixtures at high pressures

Energy Technology Data Exchange (ETDEWEB)

Donnelly, M., E-mail: m.donnelly-2@sms.ed.ac.uk; Husband, R. J.; Frantzana, A. D.; Loveday, J. S. [Centre for Science at Extreme Conditions and School of Physics and Astronomy, The University of Edinburgh, Erskine Williamson Building, Peter Guthrie Tait Road, The King’s Buildings, Edinburgh EH9 3FD (United Kingdom); Bull, C. L. [ISIS, Rutherford Appleton Laboratory, Oxford Harwell, Didcot OX11 0QX (United Kingdom); Klotz, S. [IMPMC, CNRS UMR 7590, Université P and M Curie, 4 Place Jussieu, 75252 Paris (France)

2015-03-28

Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D{sub 2} mixtures that indicate no inclusion compound forms up to 3.7 GPa.

Electron scattering in dense He-Ar gas mixtures: A pressure shift study

International Nuclear Information System (INIS)

Asaf, U.; Felps, W.S.; McGlynn, S.P.

1989-01-01

The dependence of the energies of high-n Rydberg states of CH 3 I on the molar composition of helium-argon mixtures (in the number density range 1.3x10 20 --5.6x10 20 cm -3 ) is reported. The energy shifts, when normalized to a given density value, are found to vary linearly with the mole fraction of either component of the binary, rare-gas mixture. The observed change in sign of the energy shift is attributable to the different signs of the electron scattering lengths for the two rare-gas components. As a result, there exists a mixture composition, at a mole ratio [He]/[Ar]=2.0, at which the shift is null. The experimental results for the gas mixture agree with the Fermi formula, as modified to include the Alekseev-Sobel'man polarization term. Effective electron scattering lengths and cross sections, polarizabilities, and thermal velocities are used to characterize the effects of the binary gas perturber system

Mechanism of extraction of uranium (6) by mixtures of phosphororganic extractants

International Nuclear Information System (INIS)

Skorovarov, D.I.; Ul'yanov, V.S.; Meshcheryakov, N.M.; Lagutenkov, V.A.; Mikheev, M.V.

1988-01-01

Extraction of uranium (6) from sulfuric acid solutions by solution of D2EHPA-TBP(TOPO) mixture in CCl 4 was studied by NMR method (D2HPA-di-2-ethylhexylphosphoric acid, TBP-tributylphosphate, TOPO-trioctylphosphine oxide). It is shown that stability and stoichiometry of formed solvates depends largely on electron-donor ability of organophosphoric base (TBP or TOPO). The presence of neutral base in extractive system leads to blocking of the coordination center of free D2EHPA molecules, growth of the active acid concentration, assisting in additional solvation of uranyl D2EHP molecules and formation of UO 2 (D2EHP) 2 ·nS type complexes. This results in extraction of additional U(6) quantities to organic phase

Linear Regression on Sparse Features for Single-Channel Speech Separation

DEFF Research Database (Denmark)

Schmidt, Mikkel N.; Olsson, Rasmus Kongsgaard

2007-01-01

In this work we address the problem of separating multiple speakers from a single microphone recording. We formulate a linear regression model for estimating each speaker based on features derived from the mixture. The employed feature representation is a sparse, non-negative encoding of the speech...... mixture in terms of pre-learned speaker-dependent dictionaries. Previous work has shown that this feature representation by itself provides some degree of separation. We show that the performance is significantly improved when regression analysis is performed on the sparse, non-negative features, both...

Brownian motion probe for water-ethanol inhomogeneous mixtures

Science.gov (United States)

Furukawa, Kazuki; Judai, Ken

2017-12-01

Brownian motion provides information regarding the microscopic geometry and motion of molecules, insofar as it occurs as a result of molecular collisions with a colloid particle. We found that the mobility of polystyrene beads from the Brownian motion in a water-ethanol mixture is larger than that predicted from the liquid shear viscosity. This indicates that mixing water and ethanol is inhomogeneous in micron-sized probe beads. The discrepancy between the mobility of Brownian motion and liquid mobility can be explained by the way the rotation of the beads in an inhomogeneous viscous solvent converts the translational movement.

Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature

Science.gov (United States)

Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

2016-01-01

Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons. PMID:26892255

Theory and simulations for hard-disk models of binary mixtures of molecules with internal degrees of freedom

DEFF Research Database (Denmark)

Fraser, Diane P.; Zuckermann, Martin J.; Mouritsen, Ole G.

1991-01-01

A two-dimensional Monte Carlo simulation method based on the NpT ensemble and the Voronoi tesselation, which was previously developed for single-species hard-disk systems, is extended, along with a version of scaled-particle theory, to many-component mixtures. These systems are unusual in the sense...... and internal degrees of freedom leads to a rich phase structure that includes solid-liquid transitions (governed by the translational variables) as well as transitions involving changes in average disk size (governed by the internal variables). The relationship between these two types of transitions is studied...... by the method in the case of a binary mixture, and results are presented for varying disk-size ratios and degeneracies. The results are also compared with the predictions of the extended scaled-particle theory. Applications of the model are discussed in relation to lipid monolayers spread on air...

Mesophilic anaerobic digestion of a mixture of cheese whey and dairy manure

Energy Technology Data Exchange (ETDEWEB)

Lo, K.V.; Liao, P.H.; Chiu, C.

1988-01-01

Mesophilic anaerobic digestion of a mixture of cheese whey and dairy manure was investigated using an anaerobic rotating biological contact reactor operated over a range of hydraulic retention time at various organic loading rates. Dairy manure provided nutrients and acted as a buffer to the cheese whey. Rates of production of methane from the mixture were between those of cheese whey and screened dairy manure and in agreement with calculated theoretical methane production rates. Methane production rate showed a linear relationship with the organic loading rate. The highest methane production rate was 3.74 liter methane litre/sup -1/ day/sup -1/. Reduction in the chemical oxygen demand ranged from 46.3% to 67.5%. Anaerobic digestion of such mixtures could be used as an initial waste treatment for cheese whey.

Phase properties of elastic waves in systems constituted of adsorbed diatomic molecules on the (001) surface of a simple cubic crystal

Science.gov (United States)

Deymier, P. A.; Runge, K.

2018-03-01

A Green's function-based numerical method is developed to calculate the phase of scattered elastic waves in a harmonic model of diatomic molecules adsorbed on the (001) surface of a simple cubic crystal. The phase properties of scattered waves depend on the configuration of the molecules. The configurations of adsorbed molecules on the crystal surface such as parallel chain-like arrays coupled via kinks are used to demonstrate not only linear but also non-linear dependency of the phase on the number of kinks along the chains. Non-linear behavior arises for scattered waves with frequencies in the vicinity of a diatomic molecule resonance. In the non-linear regime, the variation in phase with the number of kinks is formulated mathematically as unitary matrix operations leading to an analogy between phase-based elastic unitary operations and quantum gates. The advantage of elastic based unitary operations is that they are easily realizable physically and measurable.

Dielectric relaxation and hydrogen bonding interaction in xylitol-water mixtures using time domain reflectometry

Science.gov (United States)

Rander, D. N.; Joshi, Y. S.; Kanse, K. S.; Kumbharkhane, A. C.

2016-01-01

The measurements of complex dielectric permittivity of xylitol-water mixtures have been carried out in the frequency range of 10 MHz-30 GHz using a time domain reflectometry technique. Measurements have been done at six temperatures from 0 to 25 °C and at different weight fractions of xylitol (0 xylitol-water can be well described by Cole-Davidson model having an asymmetric distribution of relaxation times. The dielectric parameters such as static dielectric constant and relaxation time for the mixtures have been evaluated. The molecular interaction between xylitol and water molecules is discussed using the Kirkwood correlation factor ( g eff ) and thermodynamic parameter.

Polymer Mixtures and Films: Free Volume as a Driving Force for Miscibility and Glassiness

Science.gov (United States)

DeFelice, Jeffrey

The microscopic characteristics of polymer molecules are connected with many macro- scopic and mechanical properties of their liquid (pure or mixed) and solid states. How these properties are affected by the different molecular attributes of polymers is of particular interest for practical applications of polymer materials. In Part I of this thesis, the thermodynamics of polymer/supercritical CO2 mixtures and blends of linear and branched polymers are modeled using a lattice based equation of state approach. Analyses of trends in the pure component physical properties lead to insight regarding how changes in molecular architecture and/or isotopic labeling affect the relative compatibilities of the mixtures. This approach is also applied to the mixed state to predict the enthalpic and entropic changes of mixing, from which, information is provided about the role of pure component properties in controlling the underlying thermodynamics of the mixtures. In Part II, the focus of this thesis turns to how interfacial effects can shift a number of physical properties in glass forming fluids relative to those of the pure bulk material. One of the most notable deviations from bulk behavior that has been reported for these systems is a change in the glass transition temperature (Tg). In this work, interfacial effects on Tg are probed in film and polymer/additive systems using a simple kinetic lattice model that simulates free volume and mobility in glass forming fluids. For films, the thickness-dependent behavior of Tg is characterized for different types of interfaces, including films that are substrate supported, free- standing, and 'stacked'. Connections are drawn between the size of the region of enhanced mobility near a free surface and the distribution of local Tg values across a film. For polymer/additive systems, where the "interface" is dispersed throughout the material, trends in additive induced Tg changes are analyzed with respect to additive concentration and

Thermo-acoustical molecular interaction study in binary mixtures of glycerol and ethylene glycol

Science.gov (United States)

Kaur, Kirandeep; Juglan, K. C.; Kumar, Harsh

2017-07-01

Ultrasonic velocity, density and viscosity are measured over the entire composition range for binary liquid mixtures of glycerol (CH2OH-CHOH-CH2OH) and ethylene glycol (HOCH2CH2OH) at different temperatures and constant frequency of 2MHz using ultrasonic interferometer, specific gravity bottle and viscometer respectively. Measured experimental values are used to obtained various acoustical parameters such as adiabatic compressibility, acoustic impedance, intermolecular free length, relaxation time, ultrasonic attenuation, effective molar weight, free volume, available volume, molar volume, Wada's constant, Rao's constant, Vander Waal's constant, internal pressure, Gibb's free energy and enthalpy. The variation in acoustical parameters are interpreted in terms of molecular interactions between the components of molecules of binary liquid mixtures.

About the correlation between atomic charge fluctuations in a molecule

International Nuclear Information System (INIS)

Pitanga, P.; Giambiagi, M.S. de; Giambiagi, M.

1987-01-01

In this note, the features of the correlation between the electronic charge fluctuations of a pair of atoms within a molecule are analised. Through Schwarz's inequality for random operators in the Hilbert space, the softness of an atom in a molecule is related to its valence and to the softness of the other atoms. It is concluded that in the general case this correlation (from which in turn stems the chemical bond) in non-linear. (author) [pt

Enzyme-coupled nanoparticles-assisted laser desorption ionization mass spectrometry for searching for low-mass inhibitors of enzymes in complex mixtures.

Science.gov (United States)

Salwiński, Aleksander; Da Silva, David; Delépée, Raphaël; Maunit, Benoît

2014-04-01

In this report, enzyme-coupled magnetic nanoparticles (EMPs) were shown to be an effective affinity-based tool for finding specific interactions between enzymatic targets and the low-mass molecules in complex mixtures using classic MALDI-TOF apparatus. EMPs used in this work act as nonorganic matrix enabling ionization of small molecules without any interference in the low-mass range (enzyme-coupled nanoparticles-assisted laser desorption ionization MS, ENALDI MS) and simultaneously carry the superficial specific binding sites to capture inhibitors present in a studied mixture. We evaluated ENALDI approach in two complementary variations: 'ion fading' (IF-ENALDI), based on superficial adsorption of inhibitors and 'ion hunting' (IH-ENALDI), based on selective pre-concentration of inhibitors. IF-ENALDI was applied for two sets of enzyme-inhibitor pairs: tyrosinase-glabridin and trypsin-leupeptin and for the real plant sample: Sparrmannia discolor leaf and stem methanol extract. The efficacy of IH-ENALDI was shown for the pair of trypsin-leupeptin. Both ENALDI approaches pose an alternative for bioassay-guided fractionation, the common method for finding inhibitors in the complex mixtures.

Improvement in device performance from a mixture of a liquid crystal and photosensitive acrylic prepolymer with the photoinduced vertical alignment method

Directory of Open Access Journals (Sweden)

Czung-Yu Ho, Fa-Hsin Lin, Yu-Tai Tao and Jiunn-Yih Lee

2011-01-01

Full Text Available In a multicomponent nematic liquid crystal (NLC mixture of a liquid crystal (negative-type NLC and a photosensitive acrylic prepolymer, photopolymerization upon UV irradiation induces the separation of the LC and photosensitive acrylic prepolymer layers, thereby leading to a vertical arrangement of LC molecules. In this study, we propose a simple vertical alignment method for LC molecules, by adding a chiral smectic A (SmA* liquid crystal having homeotropic texture characteristics to an NLC mixture solution. Measurements of electro-optical properties revealed that the addition of the SmA* LC not only strengthened the anchoring force of the copolymer alignment film surface, but also significantly enhanced the contrast ratio (~73%, response time and grayscale switching performance of the device.

Automatic NMR-based identification of chemical reaction types in mixtures of co-occurring reactions.

Science.gov (United States)

Latino, Diogo A R S; Aires-de-Sousa, João

2014-01-01

the molecules in the mixtures.

Automatic NMR-based identification of chemical reaction types in mixtures of co-occurring reactions.

Directory of Open Access Journals (Sweden)

Diogo A R S Latino

elucidation of the molecules in the mixtures.

Electron collision cross sections and electron swarm parameters for gas molecules

International Nuclear Information System (INIS)

Hayashi, Makoto

1986-01-01

Elastic and inelastic electron collision cross sections for molecules which interest in radiation research have been determined from available electron beam and electron swarm data by utilizing the Boltzmann equation and Monte Carlo simulation method. Electron drift velocity data which interest in radiation Pysics have been discussed and some calculated results of electron drift velocity data for CF 4 and CF 4 -inert gases mixtures will be presented. (author)

Retrieval of interatomic separations of molecules from laser-induced high-order harmonic spectra

International Nuclear Information System (INIS)

Le, Van-Hoang; Nguyen, Ngoc-Ty; Jin, C; Le, Anh-Thu; Lin, C D

2008-01-01

We illustrate an iterative method for retrieving the internuclear separations of N 2 , O 2 and CO 2 molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible

Conductance mechanism in a linear non-conjugated trimethylsilyl-acetylene molecule: tunneling through localized states

NARCIS (Netherlands)

Petrov, E.G.; Marchenko, A.; Kapitanchuk, O.; Katsonis, Nathalie Hélène; Fichou, D.

2014-01-01

The conductance properties of 1,3-(trimethylsilyl)-1-tridecene-6,12-diyne, a non-conjugated trimethylsil-acetylene molecule have been investigated both experimentally and theoretically. Based on scanning tunnelling spectroscopy experiments, a discussion on the mechanisms controlling the charge

Technical note: A linear model for predicting δ13 Cprotein.

Science.gov (United States)

Pestle, William J; Hubbe, Mark; Smith, Erin K; Stevenson, Joseph M

2015-08-01

Development of a model for the prediction of δ(13) Cprotein from δ(13) Ccollagen and Δ(13) Cap-co . Model-generated values could, in turn, serve as "consumer" inputs for multisource mixture modeling of paleodiet. Linear regression analysis of previously published controlled diet data facilitated the development of a mathematical model for predicting δ(13) Cprotein (and an experimentally generated error term) from isotopic data routinely generated during the analysis of osseous remains (δ(13) Cco and Δ(13) Cap-co ). Regression analysis resulted in a two-term linear model (δ(13) Cprotein (%) = (0.78 × δ(13) Cco ) - (0.58× Δ(13) Cap-co ) - 4.7), possessing a high R-value of 0.93 (r(2)  = 0.86, P analysis of human osseous remains. These predicted values are ideal for use in multisource mixture modeling of dietary protein source contribution. © 2015 Wiley Periodicals, Inc.

Universal aspects of macromolecules in polymer blends, solutions, and supercritical mixtures

International Nuclear Information System (INIS)

Melnichenko, Y.B.; Wignall, G.D.; Schwahn, D.

2002-01-01

We demonstrate that macromolecules in miscible polymer blends may behave as good, Θ, and poor polymeric solvents for each other. We construct a conceptual phase diagram, delineating the range of validity of the random-phase approximation, outside of which polymers contract or expand beyond their unperturbed dimensions, contrary to common assumptions. Remarkably, the correlation length for polymer blends, solutions, and supercritical mixtures collapses onto a master curve, reflecting universal behavior for macromolecules in polymeric and small-molecule Θ solvents

Gaussian Mixture Model of Heart Rate Variability

Science.gov (United States)

Costa, Tommaso; Boccignone, Giuseppe; Ferraro, Mario

2012-01-01

Heart rate variability (HRV) is an important measure of sympathetic and parasympathetic functions of the autonomic nervous system and a key indicator of cardiovascular condition. This paper proposes a novel method to investigate HRV, namely by modelling it as a linear combination of Gaussians. Results show that three Gaussians are enough to describe the stationary statistics of heart variability and to provide a straightforward interpretation of the HRV power spectrum. Comparisons have been made also with synthetic data generated from different physiologically based models showing the plausibility of the Gaussian mixture parameters. PMID:22666386

Single-Molecule Imaging Reveals Topology Dependent Mutual Relaxation of Polymer Chains

KAUST Repository

Abadi, Maram; Serag, Maged F.; Habuchi, Satoshi

2015-01-01

The motion and relaxation of linear and cyclic polymers under entangled conditions are investigated by means of a newly developed single-molecule tracking technique, cumulative-area (CA) tracking. CA tracking enables simultaneous quantitative characterization of the diffusion mode, diffusion rate, and relaxation time that have been impossible with a widely used conventional single-molecule localization and tracking method, by analyzing cumulative areas occupied by the moving molecule. Using the novel approach, we investigate the motion and relaxation of entangled cyclic polymers, which have been an important but poorly understood question. Fluorescently labeled 42 kbp linear or cyclic tracer dsDNAs in concentrated solutions of unlabeled linear or cyclic DNAs are used as model systems. We show that CA tracking can explicitly distinguish topology-dependent diffusion mode, rate, and relaxation time, demonstrating that the method provides an invaluable tool for characterizing topological interaction between the entangled chains. We further demonstrate that the current models proposed for the entanglement between cyclic polymers which are based on cyclic chains moving through an array of fixed obstacles cannot correctly describe the motion of the cyclic chain under the entangled conditions. Our results rather suggest the mutual relaxation of the cyclic chains, which underscore the necessity of developing a new model to describe the motion of cyclic polymer under the entangled conditions based on the mutual interaction of the chains.

Single-Molecule Imaging Reveals Topology Dependent Mutual Relaxation of Polymer Chains

KAUST Repository

Abadi, Maram

2015-08-24

The motion and relaxation of linear and cyclic polymers under entangled conditions are investigated by means of a newly developed single-molecule tracking technique, cumulative-area (CA) tracking. CA tracking enables simultaneous quantitative characterization of the diffusion mode, diffusion rate, and relaxation time that have been impossible with a widely used conventional single-molecule localization and tracking method, by analyzing cumulative areas occupied by the moving molecule. Using the novel approach, we investigate the motion and relaxation of entangled cyclic polymers, which have been an important but poorly understood question. Fluorescently labeled 42 kbp linear or cyclic tracer dsDNAs in concentrated solutions of unlabeled linear or cyclic DNAs are used as model systems. We show that CA tracking can explicitly distinguish topology-dependent diffusion mode, rate, and relaxation time, demonstrating that the method provides an invaluable tool for characterizing topological interaction between the entangled chains. We further demonstrate that the current models proposed for the entanglement between cyclic polymers which are based on cyclic chains moving through an array of fixed obstacles cannot correctly describe the motion of the cyclic chain under the entangled conditions. Our results rather suggest the mutual relaxation of the cyclic chains, which underscore the necessity of developing a new model to describe the motion of cyclic polymer under the entangled conditions based on the mutual interaction of the chains.

Multiple ionization dynamics of molecules in intense laser fields

International Nuclear Information System (INIS)

Ichimura, Atsushi; Ohyama-Yamaguchi, Tomoko

2005-01-01

A classical field-ionization model is developed for sequential multiple ionization of diatomic and linear triatomic molecules exposed to intense (∼ 10 15 W/cm 2 ) laser fields. The distance R ion of Coulomb explosion is calculated for a combination of fragment charges, by considering nonadiabatic excitation followed by field ionization associated with the inner and outer saddle points. For diatomic molecules (N 2 , NO, and I 2 ), the model explains behaviors observed in experiments, as R ion (21→31) ion (21→22) between competing charge-asymmetric and symmetric channels, and even-odd fluctuation along a principal pathway. For a triatomic molecule CO 2 , a comparison of the model with an experiment suggests that charge-symmetric (or nearly symmetric) channels are dominantly populated. (author)

The role of chemometrics in single and sequential extraction assays: a review. Part II. Cluster analysis, multiple linear regression, mixture resolution, experimental design and other techniques.

Science.gov (United States)

Giacomino, Agnese; Abollino, Ornella; Malandrino, Mery; Mentasti, Edoardo

2011-03-04

Single and sequential extraction procedures are used for studying element mobility and availability in solid matrices, like soils, sediments, sludge, and airborne particulate matter. In the first part of this review we reported an overview on these procedures and described the applications of chemometric uni- and bivariate techniques and of multivariate pattern recognition techniques based on variable reduction to the experimental results obtained. The second part of the review deals with the use of chemometrics not only for the visualization and interpretation of data, but also for the investigation of the effects of experimental conditions on the response, the optimization of their values and the calculation of element fractionation. We will describe the principles of the multivariate chemometric techniques considered, the aims for which they were applied and the key findings obtained. The following topics will be critically addressed: pattern recognition by cluster analysis (CA), linear discriminant analysis (LDA) and other less common techniques; modelling by multiple linear regression (MLR); investigation of spatial distribution of variables by geostatistics; calculation of fractionation patterns by a mixture resolution method (Chemometric Identification of Substrates and Element Distributions, CISED); optimization and characterization of extraction procedures by experimental design; other multivariate techniques less commonly applied. Copyright © 2010 Elsevier B.V. All rights reserved.

Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

Science.gov (United States)

Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

2015-06-01

An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetics of the processes, plasma parameters, and output characteristics of a UV emitter operating on XeI molecules and iodine molecules and atoms

Energy Technology Data Exchange (ETDEWEB)

Shuaibov, A. K.; Grabovaya, I. A.; Minya, A. I.; Homoki, Z. T. [Uzhgorod National University (Ukraine); Kalyuzhnaya, A. G.; Shchedrin, A. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2011-03-15

A kinetic model of the processes occurring in the plasma of a high-power low-pressure gas-discharge lamp is presented, and the output characteristics of the lamp are described. The lamp is excited by a longitudinal glow discharge and emits the I{sub 2}(D Prime -A Prime ) 342-nm and XeI(B-X) 253-nm bands and the 206.2-nm spectral line of atomic iodine. When the emitter operates in a sealed-off mode on the p(He): p(Xe): p(I{sub 2}) = 400: 120: (100-200) Pa mixture, the fractions of the UV radiation power of iodine atoms, exciplex molecules of xenon iodide, and iodine molecules comprise 55, 10, and 35%, respectively. At the optimal partial pressure, the maximum total radiation power of the lamp reaches 37 W, the energy efficiency being about 15%.

Controlling the branching ratio of photodissociation using aligned molecules

DEFF Research Database (Denmark)

Larsen, J.J.; Wendt-Larsen, I.; Stapelfeldt, H.

1999-01-01

Using a sample of iodine molecules, aligned by a strong, linearly polarized laser pulse, we control the branching ratio of the I+I and I+I* photodissociation channels by a factor of 26. The control relies on selective photoexcitation of two potential curves that each correlate adiabatically...

Estudio de volumen molar y refracción molar de miscelas de triglicéridos (triacetina, tributirina o tricaprilina) y alcoholes (etanol, 1-butanol o 1-hexanol)

OpenAIRE

Rodríguez Rodríguez, M.; Galán Vallejo, M.; Muñoz Cueto, María J.

1992-01-01

Values of molar refraction for every studied mixtures show linear plots versus molar fractions of triglyceride. Values of molar volume show this behaviour, but only for tributyrin-butanol or tricaprylin-butanol miscellas. However, in tributyrin-ethanol mixtures, volume contractions have been found, whereas triacetin-butanol and tributyrin-hexanol show volume expansions. These facts are related to the mode of being structured of the alcohol and triglyceride molecules in mixtures. A linea...

Quadratic Blind Linear Unmixing: A Graphical User Interface for Tissue Characterization

OpenAIRE

Gutierrez-Navarro, O.; Campos-Delgado, D.U.; Arce-Santana, E. R.; Jo, Javier A.

2015-01-01

Spectral unmixing is the process of breaking down data from a sample into its basic components and their abundances. Previous work has been focused on blind unmixing of multi-spectral fluorescence lifetime imaging microscopy (m-FLIM) datasets under a linear mixture model and quadratic approximations. This method provides a fast linear decomposition and can work without a limitation in the maximum number of components or end-members. Hence this work presents an interactive software which imple...

Verifying reciprocal relations for experimental diffusion coefficients in multicomponent mixtures

DEFF Research Database (Denmark)

Medvedev, Oleg; Shapiro, Alexander

2003-01-01

The goal of the present study is to verify the agreement of the available data on diffusion in ternary mixtures with the theoretical requirement of linear non-equilibrium thermodynamics consisting in symmetry of the matrix of the phenomenological coefficients. A common set of measured diffusion...... coefficients for a three-component mixture consists of four Fickian diffusion coefficients, each being reported separately. However, the Onsager theory predicts the existence of only three independent coefficients, as one of them disappears due to the symmetry requirement. Re-calculation of the Fickian...... extended sets of experimental data and reliable thermodynamic models were available. The sensitivity of the symmetry property to different thermodynamic parameters of the models was also checked. (C) 2003 Elsevier Science B.V. All rights reserved....

Study of the In2O3 molecule in the free state and in the crystal

Science.gov (United States)

Kaplan, Ilya G.; Miranda, Ulises; Trakhtenberg, Leonid I.

2018-03-01

The nanomaterials based on the In2O3 molecule are widely used as catalysts and sensors among other applications. In the present study, we discuss the possibility of using nanoclusters of In2O3 as molecular photomotors. A comparative analysis of the electronic structure of the In2O3 molecule in the free state and in the crystal is performed. For the free In2O3 molecule the geometry of its lowest structures, V-shape and linear, was optimised at the CCSD(T) level, which is the most precise computational method applied up to date to study In2O3. Using experimental crystallographic data, we determined the geometry of In2O3 in the crystal. It has a zigzag, not symmetric structure and possesses a dipole moment with magnitude slightly smaller than that of the V-structure of the free molecule (the linear structure due to its symmetry has no dipole moment). According to the Natural Atomic population analysis, the chemical structure of the linear In2O3 can be represented as O = In-O-In = O; the V-shaped molecule has the similar double- and single-bond structure. The construction of nanoclusters from ´bricksʼ of In2O3 with geometry extracted from crystal (or nanoclusters extracted directly from crystal) and their use as photo-driven molecular motors are discussed.

The dipole moments of the linear polycarbon monosulfides

International Nuclear Information System (INIS)

Murakami, Akinori

1989-01-01

The dipole moments of the linear polycarbon monosulfides, CS, C 2 S and C 3 S molecule (radical)s were calculated by ab initio SCF-CI method. The equilibrium geometries of the C n S molecules were obtained by MP3 method using the 6-31G** basis set. From the split balencetype (MIDI-4) to the Huzinaga's well tempered extended type(WT) were used to evaluate dipole moments. Final results were obtained using the WT+2d basis set and CI calculation. The calculated dipole moment of the CS molecule, 1.96 debye, is in good agreement with experimental one. The dipole moment of the C 2 S radical is calculated to be 2.81 debye and 3.66 debye for C 3 S molecule. The calculated dipole moments of the C n S will be accurate with in 0.1 debye(5%)

Small and large deformation behaviour of mixtures of xanthan and enzyme modified galactomannans

NARCIS (Netherlands)

Kloek, W.; Luyten, H.; Vliet, van T.

1996-01-01

Small and large deformation properties of aqueous mixtures of xanthan with enzyme modified galactomannans at low ionic strength are discussed in terms of the theory of rubber elasticity and the structure of the galactomannans. The linear deformation region of the gels is small indicating that the

Correlation between the Inhibition of Positronium Formation by Scavenger Molecules, and Chemical Reaction Rate of Electrons with these Molecules in Nonpolar Liquids

DEFF Research Database (Denmark)

Levay, B.; Mogensen, O. E.

1977-01-01

a correlation between the inhibition coefficient and the chemical rate constant of electrons with scavenger molecules. We found that the dependence of the inhibition coefficient on the work function (VOo)f electrons in different liquids shows a very unusual behavior, similar to that recently found...... for the chemical rate constants of quasifree electrons with the same scavenger molecules. The inhibition coefficient as a function of Vo had a maximum for C2HsBr, while it increased monotonously with decreasing V, for CC14. The inhibition coefficient for C2H5Br in a 1:l molar tetramethylsilane......-n-tetradecane mixture was found to be greater than in both of the pure components. The clear correlation found between electron scavenging rate constants and positronium inhibition constitutes the severest test to date of the spur reaction model of positronium formation. The importance of the positron annihilation...

Augmenting Scheffe Linear Mixture Models With Squared and/or Crossproduct Terms

International Nuclear Information System (INIS)

Piepel, Gregory F.; Szychowski, Jeffrey M.; Loeppky, Jason L.

2001-01-01

A glass composition variation study (CVS) for high-level waste (HLW) stored at the Idaho National Engineering and Environmental Laboratory (INEEL) is being statistically designed and performed in phases over several years. The purpose of the CVS is to investigate and model how HLW-glass properties depend on glass composition within a glass composition region compatible with the expected range of INEEL HLW. The resulting glass property-composition models will be used to develop desirable glass formulations and other purposes. Phases 1 and 2 of the CVS have been completed so far, and are briefly described. The main focus of this paper is the CVS Phase 3 experimental design (test matrix). The Phase 3 experimental design was chosen to augment the Phase 1 and 2 data with additional data points, as well as to account for additional glass components of interest not studied in Phases 1 and/or 2. The paper describes how these Phase 3 experimental design augmentation challenges were addressed using the previous data, preliminary property-composition models, and statistical mixture experiment and optimal experimental design methods and software. The resulting Phase 3 experimental design of 30 simulated HAW glasses is presented and discussed

Retrieval of interatomic separations of molecules from laser-induced high-order harmonic spectra

Energy Technology Data Exchange (ETDEWEB)

Le, Van-Hoang; Nguyen, Ngoc-Ty [Department of Physics, University of Pedagogy, 280 An Duong Vuong, Ward 5, Ho Chi Minh City (Viet Nam); Jin, C; Le, Anh-Thu; Lin, C D [J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506 (United States)

2008-04-28

We illustrate an iterative method for retrieving the internuclear separations of N{sub 2}, O{sub 2} and CO{sub 2} molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible.

Effect of dipole polarizability on positron binding by strongly polar molecules

International Nuclear Information System (INIS)

Gribakin, G F; Swann, A R

2015-01-01

A model for positron binding to polar molecules is considered by combining the dipole potential outside the molecule with a strongly repulsive core of a given radius. Using existing experimental data on binding energies leads to unphysically small core radii for all of the molecules studied. This suggests that electron–positron correlations neglected in the simple model play a large role in determining the binding energy. We account for these by including the polarization potential via perturbation theory and non-perturbatively. The perturbative model makes reliable predictions of binding energies for a range of polar organic molecules and hydrogen cyanide. The model also agrees with the linear dependence of the binding energies on the polarizability inferred from the experimental data (Danielson et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 235203). The effective core radii, however, remain unphysically small for most molecules. Treating molecular polarization non-perturbatively leads to physically meaningful core radii for all of the molecules studied and enables even more accurate predictions of binding energies to be made for nearly all of the molecules considered. (paper)

Relative Permittivity of Carbon Dioxide + Ethanol Mixtures prediction by means of Artificial Neural Networks

Directory of Open Access Journals (Sweden)

Gonzalo Astray

2014-07-01

Full Text Available CO2 + ethanol mixtures have a huge scientific interest and enormous relevance for many industrial processes. Obtaining of their chemical and physical properties is a fundamental task. Relative permittivity (r of these mixtures is a key property because allows a better knowledge of the structure and the interactions in other media. In this work predictive values of relative permittivity (r of carbon dioxide + ethanol mixtures were obtained implementing artificial neural networks (ANNs. They are used successfully in very different fields; therefore it is a very useful tool. In this case the obtained results enhance the ones from the usual multiple linear regression analysis. In both cases mass fraction, pressure and temperature experimental data from a direct capacitance method were used.

Research of Deformation of Clay Soil Mixtures Mixtures

OpenAIRE

Romas Girkontas; Tadas Tamošiūnas; Andrius Savickas

2014-01-01

The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bear...

Deciding which chemical mixtures risk assessment methods work best for what mixtures

International Nuclear Information System (INIS)

Teuschler, Linda K.

2007-01-01

The most commonly used chemical mixtures risk assessment methods involve simple notions of additivity and toxicological similarity. Newer methods are emerging in response to the complexities of chemical mixture exposures and effects. Factors based on both science and policy drive decisions regarding whether to conduct a chemical mixtures risk assessment and, if so, which methods to employ. Scientific considerations are based on positive evidence of joint toxic action, elevated human exposure conditions or the potential for significant impacts on human health. Policy issues include legislative drivers that may mandate action even though adequate toxicity data on a specific mixture may not be available and risk assessment goals that impact the choice of risk assessment method to obtain the amount of health protection desired. This paper discusses three important concepts used to choose among available approaches for conducting a chemical mixtures risk assessment: (1) additive joint toxic action of mixture components; (2) toxicological interactions of mixture components; and (3) chemical composition of complex mixtures. It is proposed that scientific support for basic assumptions used in chemical mixtures risk assessment should be developed by expert panels, risk assessment methods experts, and laboratory toxicologists. This is imperative to further develop and refine quantitative methods and provide guidance on their appropriate applications. Risk assessors need scientific support for chemical mixtures risk assessment methods in the form of toxicological data on joint toxic action for high priority mixtures, statistical methods for analyzing dose-response for mixtures, and toxicological and statistical criteria for determining sufficient similarity of complex mixtures

Carbon Monoxide: An Essential Signalling Molecule

Science.gov (United States)

Mann, Brian E.

Carbon monoxide (CO), like nitric oxide (NO), is an essential signalling molecule in humans. It is active in the cardiovascular system as a vasodilator. In addition, CO possesses anti-inflammatory, anti-apoptotic and anti-proliferative properties and protects tissues from hypoxia and reperfusion injury. Some of its applications in animal models include suppression of organ graft rejection and safeguarding the heart during reperfusion after cardiopulmonary bypass surgery. CO also suppresses arteriosclerotic lesions following angioplasty, reverses established pulmonary hypertension and mitigates the development of post-operative ileus in the murine small intestine and the development of cerebral malaria in mice as well as graft-induced intimal hyperplasia in pigs. There have been several clinical trials using air-CO mixtures for the treatment of lung-, heart-, kidney- and abdominal-related diseases. This review examines the research involving the development of classes of compounds (with particular emphasis on metal carbonyls) that release CO, which could be used in clinically relevant conditions. The review is drawn not only from published papers in the chemical literature but also from the extensive biological literature and patents on CO-releasing molecules (CO-RMs).

Thermodiffusion Coefficient Analysis of n-Dodecane /n-Hexane Mixture at Different Mass Fractions and Pressure Conditions

Science.gov (United States)

Lizarraga, Ion; Bou-Ali, M. Mounir; Santamaría, C.

2018-03-01

In this study, the thermodiffusion coefficient of n-dodecane/n-hexane binary mixture at 25 ∘C mean temperature was determined for several pressure conditions and mass fractions. The experimental technique used to determine the thermodiffusion coefficient was the thermograviational column of cylindrical configuration. In turn, thermophysical properties, such as density, thermal expansion, mass expansion and dynamic viscosity up to 10 MPa were also determined. The results obtained in this work showed a linear relation between the thermophysical properties and the pressure. Thermodiffusion coefficient values confirm a linear effect when the pressure increases. Additionally, a new correlation based on the thermodiffusion coefficient for n C12/n C6 binary mixture at 25 ∘C temperature for any mass fraction and pressures, which reproduces the data within the experimental error, was proposed.

Separation of molecular hydrogen isotope mixtures on zeolite NaX-3M

International Nuclear Information System (INIS)

Polevoj, A.S.; Yudin, I.P.

1984-01-01

The transfer unito height (TUH) have been determined at separation of the H 2 -D 2 mixture using zeolite NaX-3M depending on temperature and linear gas flow rate in the column. Experimentally the TUH value has been determined by the method of stepped variation of the concentration of one of the separated components at the entrance into the column and measurement of the substance front wash-out at the outlet. The results of determining TUH in the column of 10 mm diameter filled by the zeolite immobile layer with granules of 2-3 mm size show that with increasing the temperature from 77 K to 87.3 K TUH decreases while at constant temperature it increases with the growth of linear gas flow rate. The mentioned above circumstances testify to the essential contribution to the TUH value of the hydrogen diffusion process in the sorbent grain. The given TUH absolute values indicate the high rate of interphase isotope exchange at separation of the H 2 -D 2 mixture using NaX-3M zeolite

Zero-phonon-line emission of single molecules for applications in quantum information processing

Science.gov (United States)

Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

2005-07-01

A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

Study of intermolecular interactions in binary mixtures of 2-(dimethylamino)ethanol with methanol and ethanol at various temperatures

International Nuclear Information System (INIS)

Pandey, Puneet Kumar; Pandey, Vrijesh Kumar; Awasthi, Anjali; Nain, Anil Kumar; Awasthi, Aashees

2014-01-01

Graphical abstract: The densities and ultrasonic speeds of the binary mixtures over the entire composition range were measured at various temperatures at atmospheric pressure. The excess molar volumes, isentropic compressibilities, and molar isentropic compressions have been calculated. The variations of these parameters with composition and temperature are discussed. The IR spectra were recorded they further supported the conclusion drawn from excess parameters, which indicates the presence of intermolecular hydrogen bonding between the oxygen atom of DMAE molecules and hydrogen atom of methanol and ethanol molecules in these mixtures.. - Highlights: • The study reports density and ultrasonic velocity data of 2-(dimethylamino)ethanol + methanol/ethanol mixtures. • To elucidate the interactions in 2-(dimethylamino)ethanol + methanol/ethanol binary mixtures. • Provides information on nature and relative strength of interactions in these mixtures. • Correlates physicochemical properties with interactions in these mixtures. - Abstract: The densities, ρ and ultrasonic speeds, u of the binary mixtures of 2-(dimethylamino)ethanol (DMAE) with methanol/ethanol, including those of pure liquids, over the entire composition range were measured at 298.15, 308.15 and 318.15 K. From the experimental data, the excess molar volumes, V m E and excess isentropic compressibilities, κ s E have been calculated. The excess partial molar volumes, V ¯ m,1 E and V ¯ m,2 E and excess partial molar isentropic compressions, K ¯ s,m,1 E and K ¯ s,m,2 E over the whole composition range; and partial molar volumes, V ¯ m,1 ° and V ¯ m,2 ° , partial molar isentropic compressions, K ¯ s,m,1 ° and K ¯ s,m,2 ° , excess partial molar volumes, V ¯ m,1 °E and V ¯ m,2 °E , and excess partial molar isentropic compressions, K ¯ s,m,1 °E and K ¯ s,m,2 °E at infinite dilution have also been calculated. The variations of these parameters with composition and temperature are

Hydraulic properties of domestic bentonite-sand mixture as a backfill material in the high-level waste repository

Energy Technology Data Exchange (ETDEWEB)

Cho, Won Jin; Lee, Jae Owan; Kang, Chul Hyung [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-02-01

This study is intended to investigate the effect of dry density and sand content on hydraulic conductivities of bentonite-sand mixtures. The hydraulic conductivities of bentonite-sand mixtures with dry densities of 1.6 and 1.8 Mg/m{sup 3} are lower than 10{sup -11} m/s if their sand contents are less than 70 wt%. However at the sand content of 90 wt%, the hydraulic conductivities increase sharply. In the case of sand contents not exceeding 70 wt%, the logarithm of the hydraulic conductivity of bentonite-sand mixture increase linearly with increasing sand content. The hydraulic conductivity of the mixture can be explained using 'effective clay dry density' concept. 16 refs., 21 figs., 5 tabs. (Author)

Combustion of methane-oxygen and methane-oxygen-CFC mixtures initiated by a high-current slipping surface discharge

International Nuclear Information System (INIS)

Kossyi, I.A.; Silakov, V.P.; Tarasova, N.M.

2001-01-01

Results are presented from experimental studies of the destruction of chlorofluorocarbon (CF 2 Cl 2 ) molecules in a methane-oxygen (air) gas mixture whose combustion is initiated by a high-current slipping surface discharge. It is found that a three-component CH 4 + O 2 (air)+ CF 2 Cl 2 gas mixture (even with a considerable amount of the third component) demonstrates properties of explosive combustion involving chain reactions that are typical of two-component CH 4 + O 2 mixtures. Experiments show the high degree of destruction (almost complete decomposition) of chlorofluorocarbons contained in the mixture during one combustion event. The combustion dynamics is studied. It is shown that the combustion initiated by a slipping surface discharge has a number of characteristic features that make it impossible to identify the combustion dynamics with the formation of a combustion or detonation wave. The features of the effects observed can be related to intense UV radiation produced by a pulsed high-current surface discharge

Libraries for spectrum identification: Method of normalized coordinates versus linear correlation

International Nuclear Information System (INIS)

Ferrero, A.; Lucena, P.; Herrera, R.G.; Dona, A.; Fernandez-Reyes, R.; Laserna, J.J.

2008-01-01

In this work it is proposed that an easy solution based directly on linear algebra in order to obtain the relation between a spectrum and a spectrum base. This solution is based on the algebraic determination of an unknown spectrum coordinates with respect to a spectral library base. The identification capacity comparison between this algebraic method and the linear correlation method has been shown using experimental spectra of polymers. Unlike the linear correlation (where the presence of impurities may decrease the discrimination capacity), this method allows to detect quantitatively the existence of a mixture of several substances in a sample and, consequently, to beer in mind impurities for improving the identification

Uni- and tridimensional alignment of molecules by femto-second laser pulse

International Nuclear Information System (INIS)

Rouzee, Arnaud

2007-01-01

This thesis is devoted to the study of the alignment of linear and asymmetric top molecules generated by an intense laser pulse. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. We study theoretically and experimentally the effects of intensity, temperature and polarization of the electric field on produced alignment. If the field is linearly polarized, the interaction leads to the alignment of the most polarizable axis of the molecule. If the field is elliptically polarized, the pulse can generate a simultaneous alignment of the three principal axes of inertia of an asymmetric top molecule (3-D alignment). This alignment can be characterized experimentally using pump-probe techniques which exploit the optical properties of the medium. They require the use of a second pulse of low intensity temporally delayed. Three techniques were exploited during this thesis. The first technique measures a depolarization due to the birefringence of the medium when the molecules are aligned. The second is based on the defocusing of the pulse on a gradient of index created following the space variation of alignment with respect to the spatial profile of the field. The last involves the creation of a grading of index to the intersection of two intense pulses, which causes the diffraction of the probe. Finally, we show experimentally that the birefringence technique can be used to quantify the 3-D alignment of an asymmetric top molecule like ethylene. (author) [fr

Single-molecule study on polymer diffusion in a melt state: Effect of chain topology

KAUST Repository

Habuchi, Satoshi

2013-08-06

We report a new methodology for studying diffusion of individual polymer chains in a melt state, with special emphasis on the effect of chain topology. A perylene diimide fluorophore was incorporated into the linear and cyclic poly(THF)s, and real-time diffusion behavior of individual chains in a melt of linear poly(THF) was measured by means of a single-molecule fluorescence imaging technique. The combination of mean squared displacement (MSD) and cumulative distribution function (CDF) analysis demonstrated the broad distribution of diffusion coefficient of both the linear and cyclic polymer chains in the melt state. This indicates the presence of spatiotemporal heterogeneity of the polymer diffusion which occurs at much larger time and length scales than those expected from the current polymer physics theory. We further demonstrated that the cyclic chains showed marginally slower diffusion in comparison with the linear counterparts, to suggest the effective suppression of the translocation through the threading-entanglement with the linear matrix chains. This coincides with the higher activation energy for the diffusion of the cyclic chains than of the linear chains. These results suggest that the single-molecule imaging technique provides a powerful tool to analyze complicated polymer dynamics and contributes to the molecular level understanding of the chain interaction. © 2013 American Chemical Society.

Single-molecule study on polymer diffusion in a melt state: Effect of chain topology

KAUST Repository

Habuchi, Satoshi; Fujiwara, Susumu; Yamamoto, Takuya; Vá cha, Martin; Tezuka, Yasuyuki

2013-01-01

We report a new methodology for studying diffusion of individual polymer chains in a melt state, with special emphasis on the effect of chain topology. A perylene diimide fluorophore was incorporated into the linear and cyclic poly(THF)s, and real-time diffusion behavior of individual chains in a melt of linear poly(THF) was measured by means of a single-molecule fluorescence imaging technique. The combination of mean squared displacement (MSD) and cumulative distribution function (CDF) analysis demonstrated the broad distribution of diffusion coefficient of both the linear and cyclic polymer chains in the melt state. This indicates the presence of spatiotemporal heterogeneity of the polymer diffusion which occurs at much larger time and length scales than those expected from the current polymer physics theory. We further demonstrated that the cyclic chains showed marginally slower diffusion in comparison with the linear counterparts, to suggest the effective suppression of the translocation through the threading-entanglement with the linear matrix chains. This coincides with the higher activation energy for the diffusion of the cyclic chains than of the linear chains. These results suggest that the single-molecule imaging technique provides a powerful tool to analyze complicated polymer dynamics and contributes to the molecular level understanding of the chain interaction. © 2013 American Chemical Society.

Photoelectron angular distributions from strong-field ionization of oriented molecules

DEFF Research Database (Denmark)

Holmegaard, Lotte; Hansen, Jonas Lerche; Kalhøj, Line

2010-01-01

The combination of ultrafast light sources with detection of molecular-frame photoelectron angular distributions (MFPADs) is setting new standards for detailed interrogation of molecular dynamics. However, until recently measurement of MFPADs relied on determining the molecular orientation after...... ionization, which is limited to species and processes where ionization leads to fragmentation. An alternative is to fix the molecular frame before ionization. The only demonstrations of such spatial orientation involved aligned small linear nonpolar molecules. Here we extend these techniques to the general...... class of polar molecules. Carbonylsulphide and benzonitrile molecules, fixed in space by combined laser and electrostatic fields, are ionized with intense, circularly polarized 30-fs laser pulses. For carbonylsulphide and benzonitrile oriented in one dimension, the MFPADs exhibit pronounced anisotropies...

Thermodynamic and spectroscopic studies on binary mixtures of imidazolium ionic liquids in ethylene glycol

Energy Technology Data Exchange (ETDEWEB)

Kumar, Bhupinder [Department of Chemistry, Kurukshetra University, Kurukshetra 136119, Haryana (India); Singh, Tejwant; Rao, K. Srinivasa [Salt and Marine Chemicals Division, Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002 (India); Pal, Amalendu, E-mail: palchem@sify.com [Department of Chemistry, Kurukshetra University, Kurukshetra 136119, Haryana (India); Kumar, Arvind, E-mail: arvind@csmcri.org [Salt and Marine Chemicals Division, Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002 (India)

2012-01-15

Highlights: > Macroscopic and molecular level interactions of imidazolium ionic liquids in ethylene glycol have been determined. > V{sub m}{sup E} is positive over the whole composition range for all the investigated mixtures. > Multiple hydrogen bonding interactions are prevailing between unlike components in mixtures of varying strengths. > Microscopic level interactions are not reflected in the mixing macroscopic behaviour. - Abstract: The thermodynamic behaviour of imidazolium based ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride [C{sub 4}mim][Cl]; 1-octyl-3-methylimidazolium chloride [C{sub 8}mim][Cl], and 1-butyl-3-methylimidazolium methylsulfate [C{sub 4}mim][C{sub 1}OSO{sub 3}] in ethylene glycol [HOCH{sub 2}CH{sub 2}OH] (EG) have been investigated over the whole composition range at T = (298.15 to 318.15) K to probe the interactions in bulk. For the purpose, volumetric properties such as excess molar volume, V{sub m}{sup E}, apparent molar volume, V{sub {phi},i}, and its limiting values at infinite dilution, V{sub {phi},i}{sup {infinity}}, have been calculated from the experimental density measurements. The molecular scale interactions between ionic liquids and EG have been investigated through Fourier transform infrared (FTIR) and {sup 1}H NMR spectroscopy. The shift in the vibrational frequency for C-H stretch of aromatic ring protons of ILs and O-H stretch of EG molecules has been analysed. The NMR chemical shifts for various protons of RTILS or EG molecules and their deviations show multiple hydrogen bonding interactions of varying strengths between RTILs and EG in their binary mixtures.

Acenes, Heteroacenes and Analogous Molecules for Organic Photovoltaic and Field Effect Transistor Applications

Science.gov (United States)

Granger, Devin Benjamin

Polycyclic aromatic hydrocarbons composed of benzenoid rings fused in a linear fashion comprise the class of compounds known as acenes. The structures containing three to six ring fusions are brightly colored and possess band gaps and charge transport efficiencies sufficient for semiconductor applications. These molecules have been investigated throughout the past several decades to assess their optoelectronic properties. The absorption, emission and charge transport properties of this series of molecules has been studied extensively to elucidate structure-property relationships. A wide variety of analogous molecules, incorporating heterocycles in place of benzenoid rings, demonstrate similar properties to the parent compounds and have likewise been investigated. Functionalization of acene compounds by placement of groups around the molecule affects the way in which molecules interact in the solid state, in addition to the energetics of the molecule. The use of electron donating or electron withdrawing groups affects the frontier molecular orbitals and thus affects the optical and electronic gaps of the molecules. The use of bulky side groups such as alkylsilylethynyl groups allows for crystal engineering of molecular aggregates, and changing the volume and dimensions of the alkylsilyl groups affects the intermolecular interactions and thus changes the packing motif. In chapter 2, a series of tetracene and pentacene molecules with strongly electron withdrawing groups is described. The investigation focuses on the change in energetics of the frontier molecular orbitals between the base acene and the nitrile and dicyanovinyl derivatives as well as the differences between the pentacene and tetracene molecules. The differences in close packing motifs through use of bulky alkylsilylethynyl groups is also discussed in relation to electron acceptor material design and bulk heterojunction organic photovoltaic characteristics. Chapter 3 focuses on molecular acceptor and

Determination of bromide in aqueous solutions via the TlBr molecule using high-resolution continuum source graphite furnace molecular absorption spectrometry

Science.gov (United States)

Cacho, Frantisek; Machynak, Lubomir; Nemecek, Martin; Beinrohr, Ernest

2018-06-01

The paper describes the determination of bromide by evaluating the molecular absorption of thallium mono-bromide (TlBr) at the rotational line at 342.9815 nm by making use a high-resolution continuum source graphite furnace atomic absorption spectrometer. The effects of variables such as the wavelength, graphite furnace program, amount of Tl and the use of a modifier were investigated and optimized. Various chemical modifiers have been studied, such as Pd, Mg, Ag and a mixture of Pd/Mg. It was found that best results were obtained by using Ag which prevents losses of bromide during pyrolysis step through precipitation of bromide as AgBr. In this way, a maximum pyrolysis temperature of 400 °C could be used. The optimum molecule forming temperature was found to be 900 °C. Bromide concentrations in various water samples (CRM, bottled drinking water and tap water) were determined. The quantification was made by both linear calibration and standard addition techniques. The results were matched well those of the reference method. The calibration curve was linear in the range between 1 and 1000 ng Br with a correlation coefficient R = 0.999. The limit of detection and characteristic mass of the method were 0.3 ng and 4.4 ng of Br.

Combining measurements to estimate properties and characterization extent of complex biochemical mixtures; applications to Heparan Sulfate

Science.gov (United States)

Pradines, Joël R.; Beccati, Daniela; Lech, Miroslaw; Ozug, Jennifer; Farutin, Victor; Huang, Yongqing; Gunay, Nur Sibel; Capila, Ishan

2016-04-01

Complex mixtures of molecular species, such as glycoproteins and glycosaminoglycans, have important biological and therapeutic functions. Characterization of these mixtures with analytical chemistry measurements is an important step when developing generic drugs such as biosimilars. Recent developments have focused on analytical methods and statistical approaches to test similarity between mixtures. The question of how much uncertainty on mixture composition is reduced by combining several measurements still remains mostly unexplored. Mathematical frameworks to combine measurements, estimate mixture properties, and quantify remaining uncertainty, i.e. a characterization extent, are introduced here. Constrained optimization and mathematical modeling are applied to a set of twenty-three experimental measurements on heparan sulfate, a mixture of linear chains of disaccharides having different levels of sulfation. While this mixture has potentially over two million molecular species, mathematical modeling and the small set of measurements establish the existence of nonhomogeneity of sulfate level along chains and the presence of abundant sulfate repeats. Constrained optimization yields not only estimations of sulfate repeats and sulfate level at each position in the chains but also bounds on these levels, thereby estimating the extent of characterization of the sulfation pattern which is achieved by the set of measurements.

The mechanism of three-body process of energy transfer from excited xenon atoms to molecules

International Nuclear Information System (INIS)

Wojciechowski, K.; Forys, M.

1999-01-01

The mechanism of energy transfer from Xe(6 s[3/2] 1 ) resonance state (E=8.44 eV) and higher excited Xe(6p, 6p', 6 d) atoms produced in pulse radiolysis to molecules have been discussed. The analysis of the kinetic data for these processes shows that in the sensitized photolysis and radiolysis of Xe-M mixtures the excited atoms decay in 'ordinary' two-body reaction: Xe(6s[3/2] 1 0 )+M→products (r.1) and in fast 'accelerated' third order process: Xe(6s[3/2] 1 0 )+M+Xe→products (r.2) The discussion shows that three-body process occurs via reactions: Xe(6s[3/2] 1 0 )+Xe k w ↔ k d Xe 2 ** (r.2a) Xe 2 **+M k q →[Xe 2 M]*→products (r.2b) It was shown that this mechanism concerns also higher excited Xe atoms and can explain a similar process in He-M mixtures and suggests that it is a general mechanism of energy transfer in all irradiated rare gas-molecule systems

Thermodynamics of (1-alkanol + linear monoether) systems

International Nuclear Information System (INIS)

Gonzalez, Juan Antonio; Mozo, Ismael; Garcia de la Fuente, Isaias; Cobos, Jose Carlos; Riesco, Nicolas

2008-01-01

Densities, ρ, and speeds of sound, u, of systems formed by 1-heptanol, or 1-octanol, or 1-decanol and dibutylether have been measured at a temperature of (293.15, 298.15, and 303.15) K and atmospheric pressure using a vibrating tube densimeter and sound analyser Anton Paar model DSA-5000. The ρ and u values were used to calculate excess molar volumes, V E , and deviations from the ideal behaviour of the thermal expansion coefficient, Δα p and of the isentropic compressibilities, Δκ S . The available database on molar excess enthalpies, H E , and V E for (1-alkanol + linear monoether) systems was used to investigate interactional and structural effects in such mixtures. The enthalpy of the OH...O bonds is lower for methanol solutions, and for the remainder systems, it is practically independent of the mixture compounds. The V E variation with the chain length of the 1-alkanol points out the existence of structural effects for systems including longer 1-alkanols. The ERAS model is applied to the studied mixtures. ERAS represents quite accurately H E and V E data using parameters which consistently depend on the molecular structure

On electron attachment effect on characteristics of the DBD in chlorine and its mixtures with xenon

Science.gov (United States)

Avtaeva, S. V.

2017-11-01

The electron attachment effect on DBD characteristics in chlorine and its mixtures with xenon has been studied. Characteristics of the DBDs in pure chlorine and in xenon-chlorine mixtures with a chlorine fraction of 0.1-5% were modeled using the fluid model. It is shown that the electron attachment limits a magnitude of the DBD current, contributes to formation of multiple current spikes, appearance of a double layer near the dielectric surface and formation of XeCl* excimer molecules, and leads to a redistribution of the power deposited into the discharge: more power is deposited into ions and less power is deposited into electrons.

Simaltaneous determination of Paracetamol and Chlorzoxazone in authentic mixtures and capsules

International Nuclear Information System (INIS)

Wahbi, Abdel-Aziz M.; Gazy, Azza A.; Abdel-Razak, Omayma

2003-01-01

An investigation of the ethanolic extract of the pods of Albizzia Lebbeck (L.) Benth,afforded a Orthogonal functions ratio spectrophotometry has been developed and applied to the determination of paracetamol and chlorzoxazone in authentic mixtures and capsules. A basic computer program was used to facilitate the calculations behind the method. The methods have been validated. The accuracy as determined by the analysis of laboratory prepared mixture was found to be 99.0 to 100.3%with repeatabilty of less than 1% (RSD). Linearity ranges werefound to be 3.0-21.0 and 5.0-40.0ug per ml ,respectively. The methods were found to be robust to +-0.5nm shift in the wavelength scale. Certain ratios have been developed to prove specifcity. (author)

Highly Accurate Classification of Watson-Crick Basepairs on Termini of Single DNA Molecules

Science.gov (United States)

Winters-Hilt, Stephen; Vercoutere, Wenonah; DeGuzman, Veronica S.; Deamer, David; Akeson, Mark; Haussler, David

2003-01-01

We introduce a computational method for classification of individual DNA molecules measured by an α-hemolysin channel detector. We show classification with better than 99% accuracy for DNA hairpin molecules that differ only in their terminal Watson-Crick basepairs. Signal classification was done in silico to establish performance metrics (i.e., where train and test data were of known type, via single-species data files). It was then performed in solution to assay real mixtures of DNA hairpins. Hidden Markov Models (HMMs) were used with Expectation/Maximization for denoising and for associating a feature vector with the ionic current blockade of the DNA molecule. Support Vector Machines (SVMs) were used as discriminators, and were the focus of off-line training. A multiclass SVM architecture was designed to place less discriminatory load on weaker discriminators, and novel SVM kernels were used to boost discrimination strength. The tuning on HMMs and SVMs enabled biophysical analysis of the captured molecule states and state transitions; structure revealed in the biophysical analysis was used for better feature selection. PMID:12547778

Quantification of protein based on single-molecule counting by total internal reflection fluorescence microscopy with adsorption equilibrium

International Nuclear Information System (INIS)

Wang Lei; Xu Guang; Shi Zhikun; Jiang Wei; Jin Wenrui

2007-01-01

We developed a sensitive single-molecule imaging method for quantification of protein by total internal reflection fluorescence microscopy with adsorption equilibrium. In this method, the adsorption equilibrium of protein was achieved between solution and glass substrate. Then, fluorescence images of protein molecules in a evanescent wave field were taken by a highly sensitive electron multiplying charge coupled device. Finally, the number of fluorescent spots corresponding to the protein molecules in the images was counted. Alexa Fluor 488-labeled goat anti-rat IgG(H + L) was chosen as the model protein. The spot number showed an excellent linear relationship with protein concentration. The concentration linear range was 5.4 x 10 -11 to 8.1 x 10 -10 mol L -1

Diffusive transport of strontium-85 in sand-bentonite mixtures

International Nuclear Information System (INIS)

Gillham, R.W.; Robin, M.J.L.; Dytynyshyn, D.J.

1983-06-01

Diffusion experiments have been used to determine the transport of 85 Sr in sand-bentonite mixtures. The diffusion experiments were performed on one natural soil (Chalk River sand) and on seven mixtures of bentonite and silica sand, containing from 0 percent to 100 percent bentonite. Two non-reactive solutes ( 36 Cl and 3 H) and one reactive solute ( 85 Sr) were used in the study. The experiments with non-reactive solutes yielded estimates of tortuosity factors. Retardation factors were obtained from experimental porosities, experimental bulk densities, and from batch distribution coefficients (Ksub(d)). These Ksub(d) values are a simple way of describing the solute/medium reaction, and are based on the assumption that the cation-exchange reaction may be described by a linear adsorption isotherm passing through the origin. The results demonstrate that, for practical purposes and for our experimental conditions, the use of the distribution coefficient provides a convenient means of calculating the effective diffusion coefficient for 85 Sr. The porosity and bulk density were also found to have a considerable influence on the effective diffusion coefficient, through the retardation factor. Mixtures containing 5-10 percent bentonite were found to be more effective in retarding 85 Sr than either sand alone, or mixtures containing more bentonite. In the soils of higher bentonite content, the effect of increased cation-exchange capacity was balanced by a decreasing ratio of bulk density to porosity

A numerical study of blood flow using mixture theory

OpenAIRE

Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F.

2014-01-01

In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner–Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM® was developed and ...

PhyloBayes MPI: phylogenetic reconstruction with infinite mixtures of profiles in a parallel environment.

Science.gov (United States)

Lartillot, Nicolas; Rodrigue, Nicolas; Stubbs, Daniel; Richer, Jacques

2013-07-01

Modeling across site variation of the substitution process is increasingly recognized as important for obtaining more accurate phylogenetic reconstructions. Both finite and infinite mixture models have been proposed and have been shown to significantly improve on classical single-matrix models. Compared with their finite counterparts, infinite mixtures have a greater expressivity. However, they are computationally more challenging. This has resulted in practical compromises in the design of infinite mixture models. In particular, a fast but simplified version of a Dirichlet process model over equilibrium frequency profiles implemented in PhyloBayes has often been used in recent phylogenomics studies, while more refined model structures, more realistic and empirically more fit, have been practically out of reach. We introduce a message passing interface version of PhyloBayes, implementing the Dirichlet process mixture models as well as more classical empirical matrices and finite mixtures. The parallelization is made efficient thanks to the combination of two algorithmic strategies: a partial Gibbs sampling update of the tree topology and the use of a truncated stick-breaking representation for the Dirichlet process prior. The implementation shows close to linear gains in computational speed for up to 64 cores, thus allowing faster phylogenetic reconstruction under complex mixture models. PhyloBayes MPI is freely available from our website www.phylobayes.org.

Molecule Matters van der Waals Molecules

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan. Feature Article Volume 14 Issue 12 December 2009 pp 1210-1222 ...

Structures, Bonding, and Energetics of Potential Triatomic Circumstellar Molecules Containing Group 15 and 16 Elements.

Science.gov (United States)

Turner, Walter E; Agarwal, Jay; Schaefer, Henry F

2015-12-03

The recent discovery of PN in the oxygen-rich shell of the supergiant star VY Canis Majoris points to the formation of several triatomic molecules involving oxygen, nitrogen, and phosphorus; these are also intriguing targets for main-group synthetic inorganic chemistry. In this research, high-level ab initio electronic structure computations were conducted on the potential circumstellar molecule OPN and several of its heavier group 15 and 16 congeners (SPN, SePN, TePN, OPP, OPAs, and OPSb). For each congener, four isomers were examined. Optimized geometries were obtained with coupled cluster theory [CCSD(T)] using large Dunning basis sets [aug-cc-pVQZ, aug-cc-pV(Q+d)Z, and aug-cc-pVQZ-PP], and relative energies were determined at the complete basis set limit of CCSDT(Q) from focal point analyses. The linear phosphorus-centered molecules were consistently the lowest in energy of the group 15 congeners by at least 6 kcal mol(-1), resulting from double-triple and single-double bond resonances within the molecule. The linear nitrogen-centered molecules were consistently the lowest in energy of the group 16 congeners by at least 5 kcal mol(-1), due to the electronegative central nitrogen atom encouraging electron delocalization throughout the molecule. For OPN, OPP, and SPN, anharmonic vibrational frequencies and vibrationally corrected rotational constants are predicted; good agreement with available experimental data is observed.

A test of the mean density approximation for Lennard-Jones mixtures with large size ratios

International Nuclear Information System (INIS)

Ely, J.F.

1986-01-01

The mean density approximation for mixture radial distribution functions plays a central role in modern corresponding-states theories. This approximation is reasonably accurate for systems that do not differ widely in size and energy ratios and which are nearly equimolar. As the size ratio increases, however, or if one approaches an infinite dilution of one of the components, the approximation becomes progressively worse, especially for the small molecule pair. In an attempt to better understand and improve this approximation, isothermal molecular dynamics simulations have been performed on a series of Lennard-Jones mixtures. Thermodynamic properties, including the mixture radial distribution functions, have been obtained at seven compositions ranging from 5 to 95 mol%. In all cases the size ratio was fixed at two and three energy ratios were investigated, 22 / 11 =0.5, 1.0, and 1.5. The results of the simulations are compared with the mean density approximation and a modification to integrals evaluated with the mean density approximation is proposed

A nonlinear isobologram model with Box-Cox transformation to both sides for chemical mixtures.

Science.gov (United States)

Chen, D G; Pounds, J G

1998-12-01

The linear logistical isobologram is a commonly used and powerful graphical and statistical tool for analyzing the combined effects of simple chemical mixtures. In this paper a nonlinear isobologram model is proposed to analyze the joint action of chemical mixtures for quantitative dose-response relationships. This nonlinear isobologram model incorporates two additional new parameters, Ymin and Ymax, to facilitate analysis of response data that are not constrained between 0 and 1, where parameters Ymin and Ymax represent the minimal and the maximal observed toxic response. This nonlinear isobologram model for binary mixtures can be expressed as [formula: see text] In addition, a Box-Cox transformation to both sides is introduced to improve the goodness of fit and to provide a more robust model for achieving homogeneity and normality of the residuals. Finally, a confidence band is proposed for selected isobols, e.g., the median effective dose, to facilitate graphical and statistical analysis of the isobologram. The versatility of this approach is demonstrated using published data describing the toxicity of the binary mixtures of citrinin and ochratoxin as well as a new experimental data from our laboratory for mixtures of mercury and cadmium.

Genotoxic effects induced by the exposure to an environmental mixture of illicit drugs to the zebra mussel.

Science.gov (United States)

Parolini, Marco; Magni, Stefano; Castiglioni, Sara; Binelli, Andrea

2016-10-01

Despite the growing interest on the presence of illicit drugs in freshwater ecosystems, just recently the attention has been focused on their potential toxicity towards non-target aquatic species. However, these studies largely neglected the effects induced by exposure to complex mixtures of illicit drugs, which could be different compared to those caused by single psychoactive molecules. This study was aimed at investigating the genetic damage induced by a 14-day exposure to a realistic mixture of the most common illicit drugs found in surface waters worldwide (cocaine, benzoylecgonine, amphetamine, morphine and 3,4-methylenedioxymethamphetamine) on the zebra mussel (Dreissena polymorpha). The mixture caused a significant increase of DNA fragmentation and triggered the apoptotic process and micronuclei formation in zebra mussel hemocytes, pointing out its potential genotoxicity towards this bivalve species. Copyright © 2016 Elsevier Inc. All rights reserved.

Spectral luminescence studies of eosin solvation in water-alcohol mixtures

Energy Technology Data Exchange (ETDEWEB)

Ketsle, G.A.; Levshin, L.V.; Mel' nikov, G.V.; Saletskii, A.M.

1987-11-01

The authors investigate the effects of solvation of eosin molecules in binary water-propanol mixtures with the goal of assessing eosin as a candidate dye laser material. The fluorescence was measured with a Hitachi spectrofluorimeter and the absorption spectra were taken on a Specord spectrophotometer. Absorption and fluorescence were measured for different amounts of propanol in the solvent. Data are also given on excitation and de-excitation kinetics between ground and excited states. Values for quantum yields of fluorescence and phosphorescence, average excited state lifetime, and molecular volume of the dye with the solvated shell are tabulated.

I-optimal mixture designs

OpenAIRE

GOOS, Peter; JONES, Bradley; SYAFITRI, Utami

2013-01-01

In mixture experiments, the factors under study are proportions of the ingredients of a mixture. The special nature of the factors in a mixture experiment necessitates specific types of regression models, and specific types of experimental designs. Although mixture experiments usually are intended to predict the response(s) for all possible formulations of the mixture and to identify optimal proportions for each of the ingredients, little research has been done concerning their I-optimal desi...

An Image-Based Finite Element Approach for Simulating Viscoelastic Response of Asphalt Mixture

Directory of Open Access Journals (Sweden)

Wenke Huang

2016-01-01

Full Text Available This paper presents an image-based micromechanical modeling approach to predict the viscoelastic behavior of asphalt mixture. An improved image analysis technique based on the OTSU thresholding operation was employed to reduce the beam hardening effect in X-ray CT images. We developed a voxel-based 3D digital reconstruction model of asphalt mixture with the CT images after being processed. In this 3D model, the aggregate phase and air void were considered as elastic materials while the asphalt mastic phase was considered as linear viscoelastic material. The viscoelastic constitutive model of asphalt mastic was implemented in a finite element code using the ABAQUS user material subroutine (UMAT. An experimental procedure for determining the parameters of the viscoelastic constitutive model at a given temperature was proposed. To examine the capability of the model and the accuracy of the parameter, comparisons between the numerical predictions and the observed laboratory results of bending and compression tests were conducted. Finally, the verified digital sample of asphalt mixture was used to predict the asphalt mixture viscoelastic behavior under dynamic loading and creep-recovery loading. Simulation results showed that the presented image-based digital sample may be appropriate for predicting the mechanical behavior of asphalt mixture when all the mechanical properties for different phases became available.

Spin-orbit-coupled Bose-Einstein condensates of rotating polar molecules

Science.gov (United States)

Deng, Y.; You, L.; Yi, S.

2018-05-01

An experimental proposal for realizing spin-orbit (SO) coupling of pseudospin 1 in the ground manifold 1Σ (υ =0 ) of (bosonic) bialkali polar molecules is presented. The three spin components are composed of the ground rotational state and two substates from the first excited rotational level. Using hyperfine resolved Raman processes through two select excited states resonantly coupled by a microwave, an effective coupling between the spin tensor and linear momentum is realized. The properties of Bose-Einstein condensates for such SO-coupled molecules exhibiting dipolar interactions are further explored. In addition to the SO-coupling-induced stripe structures, the singly and doubly quantized vortex phases are found to appear, implicating exciting opportunities for exploring novel quantum physics using SO-coupled rotating polar molecules with dipolar interactions.

Thermodynamics of the extraction of Eu(III) and Am(III) with synergistic mixtures of thenoyltrifluoroacetone and a linear polyether

International Nuclear Information System (INIS)

Ensor, D.D.; Shah, A.H.

1983-01-01

The extractions of trivalent lanthanides and actinides by synergistic mixtures of thenoyltrifluoroacetone (HTTA) and a variety of neutral oxygen donors are well documented. The large increase in the extent of extraction of the metal ion into the organic phase is believed to occur by one of three possible mechanisms. The first involves the direct replacement of residual waters of hydration on the metal by the neutral donor. In the second proposed mechanism, the residual waters remain attached to the metal and the neutral oxygen donor hydrogen bond to the complex through the waters. The final mechanism assumes the complex is not hydrated and the addition of the neutral donor requires the metal to increase its coordination number. A recent review of the synergistic effect showed that the proper interpretation of the mechanism requires the measurement of ΔH and ΔS for the reaction. The synergistic capabilities of a linear polyether, 1,13-bis-[8-quinolyl]-1,4,7,10,13-pentaoxotridecane (K-5), in combination with HTTA to extract Am(III) and Eu(III) have been recently reported by the investigators. The presence of the K-5 in the organic phase not only increased the extraction of the trivalent metals, but also showed a preference for Am(III) over Eu(III). This result was surprising since most neutral donors do not alter the selectivity of HTTA. In an effort to better understand the synergistic mechanism of the K-5/HTTA system, the thermodynamic parameters have been measured by a temperature variation method, and results are reported in this paper. 7 references

An improved theoretical value for Zsub(eff) for low-energy positron-hydrogen-molecule scattering

International Nuclear Information System (INIS)

Armour, E.A.G.; Baker, D.J.

1986-01-01

The value of Zsub(eff), the effective number of electrons per molecule available to the positron for annihilation, is calculated for low-energy positron-hydrogen-molecule scattering using a scattering wavefunction containing terms in which the positron-electron distance is included linearly as a factor. The results at very low energy are much closer to the experimental value than any that have been obtained previously. (author)

Imitation learning of Non-Linear Point-to-Point Robot Motions using Dirichlet Processes

DEFF Research Database (Denmark)

Krüger, Volker; Tikhanoff, Vadim; Natale, Lorenzo

2012-01-01

In this paper we discuss the use of the infinite Gaussian mixture model and Dirichlet processes for learning robot movements from demonstrations. Starting point of this work is an earlier paper where the authors learn a non-linear dynamic robot movement model from a small number of observations....... The model in that work is learned using a classical finite Gaussian mixture model (FGMM) where the Gaussian mixtures are appropriately constrained. The problem with this approach is that one needs to make a good guess for how many mixtures the FGMM should use. In this work, we generalize this approach...... our algorithm on the same data that was used in [5], where the authors use motion capture devices to record the demonstrations. As further validation we test our approach on novel data acquired on our iCub in a different demonstration scenario in which the robot is physically driven by the human...

Statistical analysis of differential potentiometric precipitation titration data for a mixture of three heterovalent ions using linear characteristics

International Nuclear Information System (INIS)

Mar'yanov, B.M.; Zarubin, A.G.; Shumar, S.V.

2003-01-01

A computer-based method is proposed for data processing in the successive potentiometric precipitation titration of a three-component mixture of differently charged ions. The method was tested on the data of the titration of an artificial solution containing a mixture of Cd(II), Hg(II), and Te(IV) with diethyldithiocarbamate using a chalcogenide Cd-selective or a glassy-carbon indicator electrodes and was used for an analysis of the main components in a semiconductor material, namely, a solid solution of mercury and cadmium tellurides. For concentrations of test ions in the model solution from 7.5 x 10 -3 to 3 x 10 -4 M, the RSD value varies from 0.01 to 0.3; the determination error does not exceed 6 %. The RSD value for the semiconductor alloy lies in the range from 0.002 to 0.01 [ru

Thermodynamics of mixtures containing amines. IX. Application of the concentration-concentration structure factor to the study of binary mixtures containing pyridines

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, Juan Antonio, E-mail: jagl@termo.uva.es [G.E.T.E.F. Dpto Termodinamica y Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071 (Spain); Cobos, Jose Carlos; Garcia de la Fuente, Isaias; Mozo, Ismael [G.E.T.E.F. Dpto Termodinamica y Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071 (Spain)

2009-10-10

Binary mixtures formed by a pyridine base and an alkane, or an aromatic hydrocarbon, or a 1-alkanol have been studied in the framework of the concentration-concentration structure factor, S{sub CC}(0), formalism. Deviations between experimental data and those provided by the DISQUAC model are discussed. Systems containing alkanes are characterized by homocoordination. In pyridine + alkane mixtures, S{sub CC}(0) decreases with the chain length of the longer alkanes, due to size effects. For a given alkane, S{sub CC}(0) also decreases with the number of CH{sub 3}- groups in the pyridine base. This has been interpreted assuming that the number of amine-amine interactions available to be broken upon mixing also decreases similarly, probably as steric hindrances exerted by the methyl groups of the aromatic amine increase with the number of these groups. Homocoordination is higher in mixtures with 3,5-dimethylpyridine than in those with 2,6-dimethylpyridine. That is, steric effects exerted by methyl groups in positions 3 and 5 are stronger than when they are in positions 2 and 6. Similarly, from the application of the DISQUAC (dispersive-quasichemical) model, it is possible to conclude that homocoordination is higher in systems with 3- or 4-methylpyridine than in those involving 2-methylpyridine. Systems including aromatic hydrocarbons are nearly ideal, which seems to indicate that there is no specific interaction in such solutions. Mixtures with 1-alkanols show heterocoordination. This reveals the existence of interactions between unlike molecules, characteristic of alkanol + amine mixtures. Methanol systems show the lowest S{sub CC}(0) values due, partially, to size effects. This explains the observed decrease of homocoordination in such solutions in the order: pyridine > 2-methylpyridine > 2,6-dimethylpyridine. Moreover, as the energies of the OH-N hydrogen bonds are practically independent of the pyridine base considered when mixed with methanol, it suggests that

Charge exchange of excited mesic atoms of hydrogen isotopes in triple collisions with molecules

International Nuclear Information System (INIS)

Men'shikov, L.I.; Ponomarev, L.I.

1985-01-01

At high densities of deuterium-tritium mixture the probability for the occurrence of the isotope-exchange reaction (dμ)/sub n/+t → d+(tμ)/sub n/ from the excited states of n mesic atoms of deuterium is high in the triple collisions of mesic atoms with the molecules of hydrogen isotopes. This reaction should be taken into account in describing the kinetics of muon catalysis

Densities and viscosities of the mixtures (formamide + 2-alkanol): Experimental and theoretical approaches

International Nuclear Information System (INIS)

Almasi, Mohammad

2014-01-01

Graphical abstract: Viscosity deviations △η vs. mole fraction of FA, for binary mixtures of FA with (□) 2-PrOH, (●) 2-BuOH, (■) 2-PenOH, (◀) 2-HexOH, (◊) 2-HepOH at T = 298.15 K. The solid curves were calculated from Redlich–Kister type equation. -- Highlights: • Densities and viscosities of the mixtures (formamide + 2-alkanols) were measured. • Experiments were performed over the entire mole fraction at four temperatures. • SAFT and PC-SAFT were applied to predict the volumetric behavior of mixtures. • PRSV equation of state (EOS) has been used to predict the binary viscosities. -- Abstract: Densities and viscosities of binary liquid mixtures of formamide (FA) with polar solvents namely, 2-PrOH, 2-BuOH, 2-PenOH, 2-HexOH, and 2-HepOH, have been measured as a function of composition range at temperatures (298.15, 303.15, 308.15, 313.15) K and ambient pressure. From experimental data, excess molar volumes, V m E and viscosity deviations Δη, were calculated and correlated by Redlich–Kister type function. The effect of temperature and chain-length of the 2-alkanols on the excess molar volumes and viscosity deviations are discussed in terms of molecular interaction between unlike molecules. The statistical associating fluid theory (SAFT), and perturbed chain statistical associating fluid theory (PC-SAFT) were applied to correlate and predict the volumetric behavior of the mixtures. The best predictions were achieved with the PC-SAFT equation of state. Also the Peng–Robinson–Stryjek–Vera equation of state has been used to predict the viscosity of binary mixtures

A fitting program for potential energy surfaces of bent triatomic molecules

International Nuclear Information System (INIS)

Searles, D.J.; Nagy-Felsobuki, E.I. von

1992-01-01

A program has been developed in order to fit analytical power series expansions (Dunham, Simon-Parr-Finlan, Ogilvie and their exponential variants) and Pade approximants to discrete ab initio potential energy surfaces of non-linear triatomic molecules. The program employs standard least-squares fitting techniques using the singular decomposition method in order to dampen the higher-order coefficients (if deemed necessary) without significantly degrading the fit. The program makes full use of the symmetry of a triatomic molecule and so addresses the D 3h , C 2v and C S cases. (orig.)

Separation of benzene from mixtures with water, methanol, ethanol, and acetone: highlighting hydrogen bonding and molecular clustering influences in CuBTC

NARCIS (Netherlands)

Gutiérrez-Sevillano, J.J.; Calero, S.; Krishna, R.

2015-01-01

Configurational-bias Monte Carlo (CBMC) simulations are used to establish the potential of CuBTC for separation of water/benzene, methanol/benzene, ethanol/benzene, and acetone/benzene mixtures. For operations under pore saturation conditions, the separations are in favor of molecules that partner

Free radical generation by non-equilibrium atmospheric pressure plasma in alcohol-water mixtures: an EPR-spin trapping study

Science.gov (United States)

Uchiyama, Hidefumi; Ishikawa, Kenji; Zhao, Qing-Li; Andocs, Gabor; Nojima, Nobuyuki; Takeda, Keigo; Krishna, Murali C.; Ishijima, Tatsuo; Matsuya, Yuji; Hori, Masaru; Noguchi, Kyo; Kondo, Takashi

2018-03-01

Free radical species in aqueous solution—various alcohol-water reaction mixtures—by exposure to non-equilibrium cold atmospheric pressure Ar plasma (CAP), were monitored using electron paramagnetic resonance spin-trapping techniques with 3, 5-dibromo-4-nitrosobenzene sulfonate as a water soluble nitroso spin trap. The major radical species were formed by H-abstraction from alcohol molecules due to ·OH radicals. In the ethanol-water mixture ·CH2CH2OH produced by H abstraction from CH3 group of the ethanol and ·CH3 radicals were detected. The latter was due to the decomposition of unstable CH3·CHOH to form the ·CH3 radicals and the stable formaldehyde by C-C bond fission. These intermediates are similar to those observed by reaction with ·OH radicals generation in the H2O2-UV photolysis of the reaction mixtures. The evidence of ·CH3 radical formation in the pyrolytic decomposition of the reaction mixtures by exposure to ultrasound or in methane irradiated with microwave plasma have been reported previously. However, the pyrolytic ·CH3 radicals were not found in both plasma and H2O2-UV photolysis condition. These results suggests that free radicals produced by Ar-CAP are most likely due to the reaction between abundant ·OH radicals and alcohol molecules.

Molecule Matters van der Waals Molecules

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan. Feature Article Volume 15 Issue 7 July 2010 pp 667-674. Fulltext. Click here to view fulltext PDF. Permanent link:

Molecule database framework: a framework for creating database applications with chemical structure search capability.

Science.gov (United States)

Kiener, Joos

2013-12-11

Research in organic chemistry generates samples of novel chemicals together with their properties and other related data. The involved scientists must be able to store this data and search it by chemical structure. There are commercial solutions for common needs like chemical registration systems or electronic lab notebooks. However for specific requirements of in-house databases and processes no such solutions exist. Another issue is that commercial solutions have the risk of vendor lock-in and may require an expensive license of a proprietary relational database management system. To speed up and simplify the development for applications that require chemical structure search capabilities, I have developed Molecule Database Framework. The framework abstracts the storing and searching of chemical structures into method calls. Therefore software developers do not require extensive knowledge about chemistry and the underlying database cartridge. This decreases application development time. Molecule Database Framework is written in Java and I created it by integrating existing free and open-source tools and frameworks. The core functionality includes:•Support for multi-component compounds (mixtures)•Import and export of SD-files•Optional security (authorization)For chemical structure searching Molecule Database Framework leverages the capabilities of the Bingo Cartridge for PostgreSQL and provides type-safe searching, caching, transactions and optional method level security. Molecule Database Framework supports multi-component chemical compounds (mixtures).Furthermore the design of entity classes and the reasoning behind it are explained. By means of a simple web application I describe how the framework could be used. I then benchmarked this example application to create some basic performance expectations for chemical structure searches and import and export of SD-files. By using a simple web application it was shown that Molecule Database Framework

Laser separation of nitrogen isotopes by the IR+UV dissociation of ammonia molecules

International Nuclear Information System (INIS)

Apatin, V M; Klimin, S A; Laptev, V B; Lokhman, V N; Ogurok, D D; Pigul'skii, S V; Ryabov, E A

2008-01-01

The separation of nitrogen isotopes is studied upon successive single-photon IR excitation and UV dissociation of ammonia molecules. The excitation selectivity was provided by tuning a CO 2 laser to resonance with 14 NH 3 molecules [the 9R(30) laser line] or with 15 NH 3 molecules [the 9R(10) laser line]. Isotopic mixtures containing 4.8% and 0.37% (natural content) of the 15 NH isotope were investigated. The dependences of the selectivity and the dissociation yield for each isotopic component on the buffer gas pressure (N 2 , O 2 , Ar) and the ammonia pressure were obtained. In the limit of low NH 3 pressures (0.5-2 Torr), the dissociation selectivity α(15/14) for 15 N was 17. The selectivity mechanism of the IR+UV dissociation is discussed and the outlook is considered for the development of the nitrogen isotope separation process based on this approach. (laser isotope separation)

Single-Molecule Rotational Switch on a Dangling Bond Dimer Bearing.

Science.gov (United States)

Godlewski, Szymon; Kawai, Hiroyo; Kolmer, Marek; Zuzak, Rafał; Echavarren, Antonio M; Joachim, Christian; Szymonski, Marek; Saeys, Mark

2016-09-27

One of the key challenges in the construction of atomic-scale circuits and molecular machines is to design molecular rotors and switches by controlling the linear or rotational movement of a molecule while preserving its intrinsic electronic properties. Here, we demonstrate both the continuous rotational switching and the controlled step-by-step single switching of a trinaphthylene molecule adsorbed on a dangling bond dimer created on a hydrogen-passivated Ge(001):H surface. The molecular switch is on-surface assembled when the covalent bonds between the molecule and the dangling bond dimer are controllably broken, and the molecule is attached to the dimer by long-range van der Waals interactions. In this configuration, the molecule retains its intrinsic electronic properties, as confirmed by combined scanning tunneling microscopy/spectroscopy (STM/STS) measurements, density functional theory calculations, and advanced STM image calculations. Continuous switching of the molecule is initiated by vibronic excitations when the electrons are tunneling through the lowest unoccupied molecular orbital state of the molecule. The switching path is a combination of a sliding and rotation motion over the dangling bond dimer pivot. By carefully selecting the STM conditions, control over discrete single switching events is also achieved. Combined with the ability to create dangling bond dimers with atomic precision, the controlled rotational molecular switch is expected to be a crucial building block for more complex surface atomic-scale devices.

Laser Raman spectroscopy of the effect of solvent on the low-frequency oscillations of organic molecules

Science.gov (United States)

Brandt, N. N.; Chikishev, A. Yu.; Dolgovskii, V. I.; Lebedenko, S. I.

2007-09-01

The effect of solvent on low-frequency oscillations is studied using an example of the 1,1,2,2-tetrachloroethane (TCE) and 1,1,2,2-tetrabromoethane (TBE) molecules, which exhibit torsional oscillations in the terahertz range. Dimethylsulfoxide (DMSO) and carbon tetrachloride (CTC) are used as solvents. It is demonstrated that a decrease in the concentration of the substance under study in the TBE/CTC, TCE/DMSO, and TCE/CTC mixtures leads to a frequency shift of the low-frequency oscillation. The shift is not observed in the TBE/DMSO mixture but a decrease in the TBE concentration causes significant broadening of the low-frequency line.

Decoupling Linear and Nonlinear Associations of Gene Expression

KAUST Repository

Itakura, Alan

2013-05-01

The FANTOM consortium has generated a large gene expression dataset of different cell lines and tissue cultures using the single-molecule sequencing technology of HeliscopeCAGE. This provides a unique opportunity to investigate novel associations between gene expression over time and different cell types. Here, we create a MatLab wrapper for a powerful and computationally intensive set of statistics known as Maximal Information Coefficient, and then calculate this statistic for a large, comprehensive dataset containing gene expression of a variety of differentiating tissues. We then distinguish between linear and nonlinear associations, and then create gene association networks. Following this analysis, we are then able to identify clusters of linear gene associations that then associate nonlinearly with other clusters of linearity, providing insight to much more complex connections between gene expression patterns than previously anticipated.

Decoupling Linear and Nonlinear Associations of Gene Expression

KAUST Repository

Itakura, Alan

2013-01-01

The FANTOM consortium has generated a large gene expression dataset of different cell lines and tissue cultures using the single-molecule sequencing technology of HeliscopeCAGE. This provides a unique opportunity to investigate novel associations between gene expression over time and different cell types. Here, we create a MatLab wrapper for a powerful and computationally intensive set of statistics known as Maximal Information Coefficient, and then calculate this statistic for a large, comprehensive dataset containing gene expression of a variety of differentiating tissues. We then distinguish between linear and nonlinear associations, and then create gene association networks. Following this analysis, we are then able to identify clusters of linear gene associations that then associate nonlinearly with other clusters of linearity, providing insight to much more complex connections between gene expression patterns than previously anticipated.

Dynamic viscosity versus probe-reported microviscosity of aqueous mixtures of poly(ethylene glycol)

International Nuclear Information System (INIS)

Bhanot, Chhavi; Trivedi, Shruti; Gupta, Arti; Pandey, Shubha; Pandey, Siddharth

2012-01-01

Highlights: ► Aqueous polymer mixtures, non-toxic media of huge industrial importance, are investigated. ► Bulk viscosity of aqueous. PEG mixtures is shown to vary widely with composition and temperature. ► T-dependent viscosity follows Arrhenius behavior suggesting aqueous PEGs to be Newtonian fluids. ► Microviscosity sensed by a fluorescence ratiometric probe is estimated and correlated with viscosity. ► Microviscosity correlates well with bulk viscosity at higher PEG concentrations. - Abstract: Correlation between the dynamic viscosity (η) and the microviscosity of a hybrid green medium constituted of water and poly(ethylene glycol) (PEG) of average molar mass (200, 400, and 600) g · mol −1 , respectively, is explored over the temperatures range (10 to 90) °C across the complete composition regime. The microviscosity is obtained using a fluorescence probe 1,3-bis-(1-pyrenyl)propane (BPP), which is manifested through the ratio of the monomer-to-intramolecular excimer intensities (I M /I E ). Aqueous PEG mixtures are observed to behave similar to Newtonian fluids as the temperature dependence of dynamic viscosity follows Arrhenius-type behavior. Surprisingly, a simple and convenient linear dependence of ln η with wt% PEG of the mixture is established. The BPP I M /I E is observed, in general, to increase with the bulk dynamic viscosity of the mixture having >10 wt% PEG suggesting a good correlation between the bulk dynamic viscosity and BPP-reported microviscosity when the viscosity of the aqueous PEG mixture is relatively high.

Nonlinear vs. linear biasing in Trp-cage folding simulations

Energy Technology Data Exchange (ETDEWEB)

Spiwok, Vojtěch, E-mail: spiwokv@vscht.cz; Oborský, Pavel; Králová, Blanka [Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Technická 3, Prague 6 166 28 (Czech Republic); Pazúriková, Jana [Institute of Computer Science, Masaryk University, Botanická 554/68a, 602 00 Brno (Czech Republic); Křenek, Aleš [Institute of Computer Science, Masaryk University, Botanická 554/68a, 602 00 Brno (Czech Republic); Center CERIT-SC, Masaryk Univerzity, Šumavská 416/15, 602 00 Brno (Czech Republic)

2015-03-21

Biased simulations have great potential for the study of slow processes, including protein folding. Atomic motions in molecules are nonlinear, which suggests that simulations with enhanced sampling of collective motions traced by nonlinear dimensionality reduction methods may perform better than linear ones. In this study, we compare an unbiased folding simulation of the Trp-cage miniprotein with metadynamics simulations using both linear (principle component analysis) and nonlinear (Isomap) low dimensional embeddings as collective variables. Folding of the mini-protein was successfully simulated in 200 ns simulation with linear biasing and non-linear motion biasing. The folded state was correctly predicted as the free energy minimum in both simulations. We found that the advantage of linear motion biasing is that it can sample a larger conformational space, whereas the advantage of nonlinear motion biasing lies in slightly better resolution of the resulting free energy surface. In terms of sampling efficiency, both methods are comparable.

Combustion characteristics of nanoaluminum, liquid water, and hydrogen peroxide mixtures

Energy Technology Data Exchange (ETDEWEB)

Sabourin, J.L.; Yetter, R.A. [The Pennsylvania State University, Department of Mechanical and Nuclear Engineering, University Park, PA 16801 (United States); Risha, G.A. [The Pennsylvania State University, Division of Business and Engineering, Altoona, PA 16601 (United States); Son, S.F. [Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907 (United States); Tappan, B.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2008-08-15

An experimental investigation of the combustion characteristics of nanoaluminum (nAl), liquid water (H{sub 2}O{sub (l)}), and hydrogen peroxide (H{sub 2}O{sub 2}) mixtures has been conducted. Linear and mass-burning rates as functions of pressure, equivalence ratio ({phi}), and concentration of H{sub 2}O{sub 2} in H{sub 2}O{sub (l)} oxidizing solution are reported. Steady-state burning rates were obtained at room temperature using a windowed pressure vessel over an initial pressure range of 0.24 to 12.4 MPa in argon, using average nAl particle diameters of 38 nm, {phi} from 0.5 to 1.3, and H{sub 2}O{sub 2} concentrations between 0 and 32% by mass. At a nominal pressure of 3.65 MPa, under stoichiometric conditions, mass-burning rates per unit area ranged between 6.93 g/cm{sup 2} s (0% H{sub 2}O{sub 2}) and 37.04 g/cm{sup 2} s (32% H{sub 2}O{sub 2}), which corresponded to linear burning rates of 9.58 and 58.2 cm/s, respectively. Burning rate pressure exponents of 0.44 and 0.38 were found for stoichiometric mixtures at room temperature containing 10 and 25% H{sub 2}O{sub 2}, respectively, up to 5 MPa. Burning rates are reduced above {proportional_to}5 MPa due to the pressurization of interstitial spaces of the packed reactant mixture with argon gas, diluting the fuel and oxidizer mixture. Mass burning rates were not measured above {proportional_to}32% H{sub 2}O{sub 2} due to an anomalous burning phenomena, which caused overpressurization within the quartz sample holder, leading to tube rupture. High-speed imaging displayed fingering or jetting ahead of the normal flame front. Localized pressure measurements were taken along the sample length, determining that the combustion process proceeded as a normal deflagration prior to tube rupture, without significant pressure buildup within the tube. In addition to burning rates, chemical efficiencies of the combustion reaction were determined to be within approximately 10% of the theoretical maximum under all conditions

Surface-enhanced resonance Raman scattering spectroscopy of single R6G molecules

Institute of Scientific and Technical Information of China (English)

Zhou Zeng-Hui; Liu Li; Wang Gui-Ying; Xu Zhi-Zhan

2006-01-01

Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal silver clusters has been studied. Based on the great enhancement of the Raman signal and the quench of the fluorescence, the SERRS spectra of R6G were recorded for the samples of dye colloidal solution with different concentrations. Spectral inhomogeneity behaviours from single molecules in the dried sample films were observed with complementary evidences, such as spectral polarization, spectral diffusion, intensity fluctuation of vibrational lines and even "breathing" of the molecules. Sequential spectra observed from a liquid sample with an average of 0.3 dye molecules in the probed volume exhibited the expected Poisson distribution for actually measuring 0, 1 or 2 molecules. Difference between the SERRS spectra of R6G excited by linearly and circularly polarized light were experimentally measured.

Quantum turnstile operation of single-molecule magnets

International Nuclear Information System (INIS)

Moldoveanu, V; Dinu, I V; Tanatar, B; Moca, C P

2015-01-01

The time-dependent transport through single-molecule magnets coupled to magnetic or non-magnetic electrodes is studied in the framework of the generalized master equation method. We investigate the transient regime induced by the periodic switching of the source and drain contacts. If the electrodes have opposite magnetizations the quantum turnstile operation allows the stepwise writing of intermediate excited states. In turn, the transient currents provide a way to read these states. Within our approach we take into account both the uniaxial and transverse anisotropy. The latter may induce additional quantum tunneling processes which affect the efficiency of the proposed read-and-write scheme. An equally weighted mixture of molecular spin states can be prepared if one of the electrodes is ferromagnetic. (paper)

Evaporative and Convective Instabilities for the Evaporation of a Binary Mixture in a Bilayer System

Science.gov (United States)

Guo, Weidong; Narayanan, Ranga

2006-11-01

Evaporative convection in binary mixtures arises in a variety of industrial processes, such as drying of paint and coating technology. There have been theories devoted to this problem either by assuming a passive vapor layer or by isolating the vapor fluid dynamics. Previous work on evaporative and convective instabilities in a single component bilayer system suggests that active vapor layers play a major role in determining the instability of the interface. We have investigated the evaporation convection in binary mixtures taking into account the fluid dynamics of both phases. The liquid mixture and its vapor are assumed to be confined between two horizontal plates with a base state of zero evaporation but with linear vertical temperature profile. When the vertical temperature gradient reaches a critical value, the evaporative instability, Rayleigh and Marangoni convection set in. The effects of vapor and liquid depth, various wave numbers and initial composition of the mixture on the evaporative and convective instability are determined. The physics of the instability are explained and detailed comparison is made between the Rayleigh, Marangoni and evaporative convection in pure component and those in binary mixtures.

Thermal neutron diffusion parameters in homogeneous mixtures

Energy Technology Data Exchange (ETDEWEB)

Drozdowicz, K.; Krynicka, E. [Institute of Nuclear Physics, Cracow (Poland)

1995-12-31

A physical background is presented for a computer program which calculates the thermal neutron diffusion parameters for homogeneous mixtures of any compounds. The macroscopic absorption, scattering and transport cross section of the mixture are defined which are generally function of the incident neutron energy. The energy-averaged neutron parameters are available when these energy dependences and the thermal neutron energy distribution are assumed. Then the averaged diffusion coefficient and the pulsed thermal neutron parameters (the absorption rare and the diffusion constant) are also defined. The absorption cross section is described by the 1/v law and deviations from this behaviour are considered. The scattering cross section can be assumed as being almost constant in the thermal neutron region (which results from the free gas model). Serious deviations are observed for hydrogen atoms bound in molecules and a special study in the paper is devoted to this problem. A certain effective scattering cross section is found in this case on a base of individual exact data for a few hydrogenous media. Approximations assumed for the average cosine of the scattering angle are also discussed. The macroscopic parameters calculated are averaged over the Maxwellian energy distribution for the thermal neutron flux. An information on the input data for the computer program is included. (author). 10 refs, 4 figs, 5 tabs.

Thermal neutron diffusion parameters in homogeneous mixtures

International Nuclear Information System (INIS)

Drozdowicz, K.; Krynicka, E.

1995-01-01

A physical background is presented for a computer program which calculates the thermal neutron diffusion parameters for homogeneous mixtures of any compounds. The macroscopic absorption, scattering and transport cross section of the mixture are defined which are generally function of the incident neutron energy. The energy-averaged neutron parameters are available when these energy dependences and the thermal neutron energy distribution are assumed. Then the averaged diffusion coefficient and the pulsed thermal neutron parameters (the absorption rare and the diffusion constant) are also defined. The absorption cross section is described by the 1/v law and deviations from this behaviour are considered. The scattering cross section can be assumed as being almost constant in the thermal neutron region (which results from the free gas model). Serious deviations are observed for hydrogen atoms bound in molecules and a special study in the paper is devoted to this problem. A certain effective scattering cross section is found in this case on a base of individual exact data for a few hydrogenous media. Approximations assumed for the average cosine of the scattering angle are also discussed. The macroscopic parameters calculated are averaged over the Maxwellian energy distribution for the thermal neutron flux. An information on the input data for the computer program is included. (author). 10 refs, 4 figs, 5 tabs

Nonlinear Structured Growth Mixture Models in Mplus and OpenMx

Science.gov (United States)

Grimm, Kevin J.; Ram, Nilam; Estabrook, Ryne

2014-01-01

Growth mixture models (GMMs; Muthén & Muthén, 2000; Muthén & Shedden, 1999) are a combination of latent curve models (LCMs) and finite mixture models to examine the existence of latent classes that follow distinct developmental patterns. GMMs are often fit with linear, latent basis, multiphase, or polynomial change models because of their common use, flexibility in modeling many types of change patterns, the availability of statistical programs to fit such models, and the ease of programming. In this paper, we present additional ways of modeling nonlinear change patterns with GMMs. Specifically, we show how LCMs that follow specific nonlinear functions can be extended to examine the presence of multiple latent classes using the Mplus and OpenMx computer programs. These models are fit to longitudinal reading data from the Early Childhood Longitudinal Study-Kindergarten Cohort to illustrate their use. PMID:25419006

Evaluation of gas migration characteristics of compacted and saturated Ca-bentonite mixture

International Nuclear Information System (INIS)

Tanaka, Yukihisa; Hironaga, Michihiko

2014-01-01

In the current concept of near-surface pit disposal for low level radioactive waste, compacted bentonite mixture will be used as an engineered barrier mainly for inhibiting migration of radioactive nuclides. Hydrogen gas can be generated inside the engineered barrier mainly by the chemical interaction between aluminum and the alkaline component of cement, or water. If the gas generation rate exceeds the diffusion rate of gas molecules inside of the compacted bentonite mixture, gas will accumulate in the void space inside of the compacted bentonite mixture until its pressure becomes large enough for it to enter the compacted bentonite mixture as a discrete gaseous phase. It is expected to be not easy for gas to entering into the compacted bentonite mixture as a discrete gaseous phase because the pore of the compacted bentonite mixture is so minute. Therefore in this study, the gas migration characteristics and the effect of gas migration on the hydraulic conductivity of the compacted Ca-bentonite mixture are investigated by the gas migration tests. The effect of stress state on the migration characteristics is also investigated by the gas migration tests and by parametric study using the model of two phase flow through deformable porous media, which was originally developed by CRIEPI. Results of this study imply that : (1) Large gas breakthrough pressure, which is defined as a rapid increase of amount of discharged gas, is affected by initial stress conditions as well as Ca-bentonite content of the mixture. (2) Hydraulic conductivity measured after the large gas breakthrough is substantially the same that measured before the gas migration test. (3) Axial stress change and volume change of the specimen during the gas migration test can be reproduced by the numerical simulation using the model of two-phase flow through deformable porous media, which was originally developed by CRIEPI. (4) Gas migration of a small scale model is numerically simulated to investigate the

Excess Volumes and Excess Isentropic Compressibilities of Binary Liquid Mixtures of Trichloroethylene with Esters at 303.15 K

Science.gov (United States)

Ramanaiah, S.; Rao, C. Narasimha; Nagaraja, P.; Venkateswarlu, P.

2015-11-01

Exces volumes, VE, and excess isentropic compressibilities, κSE, have been reported as a function of composition for binary liquid mixtures of trichloroethylene with ethyl acetate, n-propyl acetate, and n-butyl acetate at 303.15 K. Isentropic compressibilities are calculated using measured sound speeds and density data for pure components and for binary mixtures. Excess volumes and excess isentropic compressibilities are found to be negative for the three systems studied over the entire composition range at 303.15 K, whereas these values become more negative with an increase of carbon chain length. The results are discussed in terms of intermolecular interactions between unlike molecules.

Linearly Polarized IR Spectroscopy Theory and Applications for Structural Analysis

CERN Document Server

Kolev, Tsonko

2011-01-01

A technique that is useful in the study of pharmaceutical products and biological molecules, polarization IR spectroscopy has undergone continuous development since it first emerged almost 100 years ago. Capturing the state of the science as it exists today, "Linearly Polarized IR Spectroscopy: Theory and Applications for Structural Analysis" demonstrates how the technique can be properly utilized to obtain important information about the structure and spectral properties of oriented compounds. The book starts with the theoretical basis of linear-dichroic infrared (IR-LD) spectroscop

A turbulence model in mixtures. First part: Statistical description of mixture

International Nuclear Information System (INIS)

Besnard, D.

1987-03-01

Classical theory of mixtures gives a model for molecular mixtures. This kind of model is based on a small gradient approximation for concentration, temperature, and pression. We present here a mixture model, allowing for large gradients in the flow. We also show that, with a local balance assumption between material diffusion and flow gradients evolution, we obtain a model similar to those mentioned above [fr

Aligned deposition and electrical measurements on single DNA molecules

International Nuclear Information System (INIS)

Eidelshtein, Gennady; Kotlyar, Alexander; Hashemi, Mohtadin; Gurevich, Leonid

2015-01-01

A reliable method of deposition of aligned individual dsDNA molecules on mica, silicon, and micro/nanofabricated circuits is presented. Complexes of biotinylated double stranded poly(dG)–poly(dC) DNA with avidin were prepared and deposited on mica and silicon surfaces in the absence of Mg 2+ ions. Due to its positive charge, the avidin attached to one end of the DNA anchors the complex to negatively charged substrates. Subsequent drying with a directional gas flow yields DNA molecules perfectly aligned on the surface. In the avidin–DNA complex only the avidin moiety is strongly and irreversibly bound to the surface, while the DNA counterpart interacts with the substrates much more weakly and can be lifted from the surface and realigned in any direction. Using this technique, avidin–DNA complexes were deposited across platinum electrodes on a silicon substrate. Electrical measurements on the deposited DNA molecules revealed linear IV-characteristics and exponential dependence on relative humidity. (paper)

Molecular Orientation in Two Component Vapor-Deposited Glasses: Effect of Substrate Temperature and Molecular Shape

Science.gov (United States)

Powell, Charles; Jiang, Jing; Walters, Diane; Ediger, Mark

Vapor-deposited glasses are widely investigated for use in organic electronics including the emitting layers of OLED devices. These materials, while macroscopically homogenous, have anisotropic packing and molecular orientation. By controlling this orientation, outcoupling efficiency can be increased by aligning the transition dipole moment of the light-emitting molecules parallel to the substrate. Light-emitting molecules are typically dispersed in a host matrix, as such, it is imperative to understand molecular orientation in two-component systems. In this study we examine two-component vapor-deposited films and the orientations of the constituent molecules using spectroscopic ellipsometry, UV-vis and IR spectroscopy. The role of temperature, composition and molecular shape as it effects molecular orientation is examined for mixtures of DSA-Ph in Alq3 and in TPD. Deposition temperature relative to the glass transition temperature of the two-component mixture is the primary controlling factor for molecular orientation. In mixtures of DSA-Ph in Alq3, the linear DSA-Ph has a horizontal orientation at low temperatures and slight vertical orientation maximized at 0.96Tg,mixture, analogous to one-component films.

Endogenous molecules released by haemocytes receiving Sargassum oligocystum extract lead to downstream activation and synergize innate immunity in white shrimp Litopenaeus vannamei.

Science.gov (United States)

Shi, Yin-Ze; Chen, Jiann-Chu; Chen, Yu-Yuan; Kuo, Yi-Hsuan; Li, Hui-Fang

2018-05-01

White shrimp Litopenaeus vannamei haemocytes receiving immunostimulating Sargassum oligocystum extract (SE) caused necrosis in haemocyte cells, which released endogenous EM-SE molecules. This study examined the immune response of white shrimp L. vannamei receiving SE and EM-SE in vitro and in vivo. Shrimp haemocytes receiving SE exhibited degranulation, changes in cell size and cell viability, necrosis and a release of EM-SE. Shrimp haemocytes receiving SE, EM-SE, and the SE + EM-SE mixture (SE + EM-SE) increased their phenoloxidase (PO) activity which was significantly higher in shrimp haemocytes receiving the SE + EM-SE mixture. Furthermore, shrimp haemocytes receiving EM-SE showed degranulation and changes in cell size and cell viability. Shrimp receiving SE, EM-SE, and SE + EM-SE all increased their immune parameters, phagocytic activity, clearance efficiency and resistance to Vibrio alginolyticus, being significantly higher in shrimp receiving SE + EM-SE. Meanwhile, the recombinant lipopolysaccharide- and β-1,3-glucan binding protein of L. vannamei (rLvLGBP) was bound to SE, EM-SE, and SE + EM-SE. We conclude that in shrimp haemocytes receiving a non-self molecule, SE in dying cells released EM-SE which led to downstream activation and synergization of the immune response. This study demonstrated that the innate immunity of shrimp was elicited and enhanced by a mixture of endogenous molecules and exogenous substances (or immunostimulants). Copyright © 2018 Elsevier Ltd. All rights reserved.

A Coarse-Grained Molecular Dynamics Study of DLPC, DMPC, DPPC, and DSPC Mixtures in Aqueous Solution

Directory of Open Access Journals (Sweden)

Roghayeh Abedi Karjiban

2013-01-01

Full Text Available The structural and dynamics properties of the bilayer comprising 128 molecules of dipalmitoylphosphatidylcholine (DPPC, dilauroylphosphatidylcholine (DLPC, dimyristoylphosphatidylcholine (DMPC, and distearoylphosphatidylcholine (DSPC in water were investigated using a coarse-grained molecular dynamics (CG-MD simulation technique. The model mixture system was simulated at 298 K under semi-isotropic pressure conditions. The aggregation was initiated from the random configurations followed by the formation of a bilayer over a period of 500 ns. The calculated values of the area per lipid, thickness, and lateral diffusion for the mixed model were different from when a single lipid was used. Our results confirmed that the chain length of the lipid molecules strongly affects the phospholipid bilayer’s physical properties.

Generation of thermodynamic data for organic liquid mixtures from molecular simulations

DEFF Research Database (Denmark)

Christensen, Steen; Peters, Günther H.j.; Hansen, Flemming Yssing

2007-01-01

Fluctuation solution theory (FST) is employed to analyze results of molecular dynamics (MD) simulations of liquid mixtures. The objective is to generate parameters for macroscopic thermodynamic property models. Two benchmark systems, benzene-methyl acetate at 303.15 K and benzene-ethanol at 298.......15 K, are used. MD simulations are performed in the isobaric-isothermal ensemble (NPT) at the respective temperatures and at a pressure of 1 atm. We use the CHARMM27 force field at different mixing ratios. We sample positions to determine the binary (between the centers-of-mass of molecules of a pair...

Controlling translational motion of neutral molecules in inhomogeneous electric fields

International Nuclear Information System (INIS)

Yamakita, Yoshihiro

2006-01-01

Hydrogen molecules are excited to Rydberg states with n=16, 17 in the presence of inhomogeneous field of an electric dipole by a vacuum ultraviolet-ultraviolet double resonance scheme. The large dipole moment produced in Stark eigenstates leads to strong forces on the molecules in the inhomogeneous electric field. Deflection and deceleration are demonstrated for a pulsed supersonic beam containing the H 2 molecules in the n=16, 17, N + =2, M J =0 Rydberg states. The Rydberg states are found to survive for over 100 μs after the dipole field is switched off. The Rydberg states have a special stability with respect to decay by predissociation. Complete deceleration to the zero mean velocity is numerically demonstrated for H 2 molecules in the higher linear low-field-seeking n=16, M J =0 Rydberg states by using a symplectic integrator of the fourth order. The calculations show that the initial velocity of 900 ms -1 with translational temperature 1 K is decelerated to 0 ms -1 with 13 mK. (author)

Strength and microstructure characteristics of the recycled rubber tire-sand mixtures as lightweight backfill.

Science.gov (United States)

Zhang, Tao; Cai, Guojun; Duan, Weihong

2018-02-01

The disposal of scrap rubber tires has induced critical environmental issue worldwide due to the rapid increase in the number of vehicles. Recycled scrap tires as a construction material in civil engineering have significant environmental benefits from a waste management perspective. A systematic study that deals with strength and microstructure characteristics of the rubber-sand mixtures is initiated, and mechanical response of the mixtures is discussed in this investigation. Experiments were conducted to evaluate the effects of rubber fraction on the basic properties including mass density (ρ), stress-strain characteristics, shear strength, and unconfined compression strength (q u ) of the rubber-sand mixtures. Additionally, scanning electron microscopy (SEM) was carried out to reveal the microstructure characteristics of the mixtures with various rubber fractions. A discussion on the micromechanics of the mixtures also was conducted. This study demonstrates that the ρ, friction angle, and q u decrease linearly with an increase in rubber fraction, whereas shear strain at peak increases. The stress-strain characteristics of the rubber-sand mixtures shift from brittle to ductile as the rubber fraction increase. These changes are attributed to remarkably lower stiffness and higher compressibility of the rubber particle compared with those of the conventional mineral aggregates. With an increase in the rubber fraction, the mechanical response of rubber-sand mixtures exhibits two types: sand-like material and rubber-like material. Rubber particle possesses the capacity to prevent the contacted sand particles from sliding at lower rubber fraction, whereas it transmits the applied loadings as the rubber fraction increased. This outcome reinforces the practicability of using recycled rubber tire-sand mixtures as a lightweight backfill in subbase/base applications.

Spontaneous radiation of a chiral molecule located near a half-space of a bi-isotropic material

Science.gov (United States)

Guzatov, D. V.; Klimov, V. V.; Poprukailo, N. S.

2013-04-01

Analytical expressions for the rate of spontaneous emission from a chiral (optically active) molecule located near a half-space occupied by a chiral (bi-isotropic) material have been obtained and analyzed in detail. It is established that the rates of spontaneous emission from the "right" and "left" enantiomers of molecules occurring near the chiral medium may significantly differ in cases of chiral materials with (i) both negative dielectric permittivity and magnetic permeability (DNG metamaterial) and (ii) negative permeability and positive permittivity (MNG metamaterial). Based on this phenomenon, DMG and MNG metamaterials can be used to create devices capable of separating right and left enantiomers in racemic mixtures.

Spontaneous radiation of a chiral molecule located near a half-space of a bi-isotropic material

Energy Technology Data Exchange (ETDEWEB)

Guzatov, D. V., E-mail: vklimov@sci.lebedev.ru [Yanka Kupala Grodno State University (Belarus); Klimov, V. V., E-mail: klimov256@gmail.com [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Poprukailo, N. S. [Yanka Kupala Grodno State University (Belarus)

2013-04-15

Analytical expressions for the rate of spontaneous emission from a chiral (optically active) molecule located near a half-space occupied by a chiral (bi-isotropic) material have been obtained and analyzed in detail. It is established that the rates of spontaneous emission from the 'right' and 'left' enantiomers of molecules occurring near the chiral medium may significantly differ in cases of chiral materials with (i) both negative dielectric permittivity and magnetic permeability (DNG metamaterial) and (ii) negative permeability and positive permittivity (MNG metamaterial). Based on this phenomenon, DMG and MNG metamaterials can be used to create devices capable of separating right and left enantiomers in racemic mixtures.

Spontaneous radiation of a chiral molecule located near a half-space of a bi-isotropic material

International Nuclear Information System (INIS)

Guzatov, D. V.; Klimov, V. V.; Poprukailo, N. S.

2013-01-01

Analytical expressions for the rate of spontaneous emission from a chiral (optically active) molecule located near a half-space occupied by a chiral (bi-isotropic) material have been obtained and analyzed in detail. It is established that the rates of spontaneous emission from the “right” and “left” enantiomers of molecules occurring near the chiral medium may significantly differ in cases of chiral materials with (i) both negative dielectric permittivity and magnetic permeability (DNG metamaterial) and (ii) negative permeability and positive permittivity (MNG metamaterial). Based on this phenomenon, DMG and MNG metamaterials can be used to create devices capable of separating right and left enantiomers in racemic mixtures.

Modelling the Preferential Solvation of Ferulic Acid in {2-Propanol (1 + Water (2} Mixtures at 298.15 K

Directory of Open Access Journals (Sweden)

Abolghasem Jouyban 1,2, Fleming Martínez 3 *

2017-12-01

Full Text Available Background: Recently Haq et al. reported the equilibrium solubility in {2-propanol (1 + water (2} mixtures at several temperatures with some numerical correlation analysis. Nevertheless, no attempt was made to evaluate the preferential solvation of this compound by the solvents. Methods: Preferential solvation of ferulic acid in the saturated mixtures at 298.15 K was analyzed based on the inverse Kirkwood-Buff integrals as described in the literature. Results: Ferulic acid is preferentially solvated by water in water-rich mixtures (0.00 < x1 < 0.19 but preferentially solvated by 2-propanol in mixtures with composition 0.19 < x1 < 1.00. Conclusion: These results could be interpreted as a consequence of hydrophobic hydration around the non-polar groups of the solute in the former case (0.00 < x1 < 0.19. Moreover, in the last case (0.19 < x1 < 1.00, the observed trend could be a consequence of the acid behavior of ferulic acid in front to 2-propanol molecules because this cosolvent is more basic than water as described by the respective solvatochromic parameters.

Novel linear polymers able to inhibit bacterial quorum sensing.

Science.gov (United States)

Cavaleiro, Eliana; Duarte, Ana Sofia; Esteves, Ana Cristina; Correia, António; Whitcombe, Michael J; Piletska, Elena V; Piletsky, Sergey A; Chianella, Iva

2015-05-01

Bacterial phenotypes, such as biofilm formation, antibiotic resistance and virulence expression, are associated with quorum sensing. Quorum sensing is a density-dependent regulatory system of gene expression controlled by specific signal molecules, such as N-acyl homoserine lactones (AHLs), produced and released by bacteria. This study reports the development of linear polymers capable to attenuate quorum sensing by adsorption of AHLs. Linear polymers were synthesized using MMA as backbone monomer and methacrylic acid and itaconic acid as functional monomers. Two different quorum sensing-controlled phenotypes, Vibrio fischeri bioluminescence and Aeromonas hydrophila biofilm formation, were evaluated to test the polymers' efficiency. Results showed that both phenotypes were significantly affected by the polymers, with the itaconic acid-containing material being more effective than the methacrylic acid one. The polymer inhibitory effects were reverted by the addition of lactones, confirming attenuation of quorum sensing through sequestration of signal molecules. The polymers also showed no cytotoxicity when tested using a mammalian cell line. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-molecule imaging reveals topological isomer-dependent diffusion by 4-armed star and dicyclic 8-shaped polymers

KAUST Repository

Habuchi, Satoshi

2015-04-21

Diffusion dynamics of topological isomers of polymer molecules was investigated at the single-molecule level in a melt state by employing the fluorophore-incorporated 4-armed star and the corresponding doubly-cyclized, 8-shaped poly(THF) chains. While the single-molecule fluorescence imaging experiment revealed that the diffusion of the 4-armed star polymer was described by a single Gaussian distribution, the diffusion of the 8-shaped polymer exhibited a double Gaussian distribution behaviour. We reasoned that the two 8-shaped polymeric isomers have distinct diffusion modes in the melt state, although ensemble-averaged experimental methods cannot detect differences in overall conformational state of the isomers. The single-molecule experiments suggested that one of the 8-shaped polymeric isomer, having the horizontally oriented form, causes an efficient threading with the linear matrix chains which leads to the slower diffusion compared with the corresponding 4-armed star polymer, while the other 8-shaped polymeric isomer, having the vertically oriented form, displayed faster diffusion by the suppression of effective threading with the linear matrix chains due to its contracted chain conformation.

Magnetic field modification of ultracold molecule-molecule collisions

International Nuclear Information System (INIS)

Tscherbul, T V; Suleimanov, Yu V; Aquilanti, V; Krems, R V

2009-01-01

We present an accurate quantum mechanical study of molecule-molecule collisions in the presence of a magnetic field. The work focuses on the analysis of elastic scattering and spin relaxation in collisions of O 2 ( 3 Σ g - ) molecules at cold (∼0.1 K) and ultracold (∼10 -6 K) temperatures. Our calculations show that magnetic spin relaxation in molecule-molecule collisions is extremely efficient except at magnetic fields below 1 mT. The rate constant for spin relaxation at T=0.1 K and a magnetic field of 0.1 T is found to be as large as 6.1x10 -11 cm -3 s -1 . The magnetic field dependence of elastic and inelastic scattering cross sections at ultracold temperatures is dominated by a manifold of Feshbach resonances with the density of ∼100 resonances per Tesla for collisions of molecules in the absolute ground state. This suggests that the scattering length of ultracold molecules in the absolute ground state can be effectively tuned in a very wide range of magnetic fields. Our calculations demonstrate that the number and properties of the magnetic Feshbach resonances are dramatically different for molecules in the absolute ground and excited spin states. The density of Feshbach resonances for molecule-molecule scattering in the low-field-seeking Zeeman state is reduced by a factor of 10.

Tunneling induced dark states and the controllable resonance fluorescence spectrum in quantum dot molecules

International Nuclear Information System (INIS)

Tian, Si-Cong; Tong, Cun-Zhu; Ning, Yong-Qiang; Qin, Li; Liu, Yun; Wan, Ren-Gang

2014-01-01

Optical spectroscopy, a powerful tool for probing and manipulating quantum dots (QDs), has been used to investigate the resonance fluorescence spectrum from linear triple quantum dot molecules controlled by tunneling, using atomic physics methods. Interesting features such as quenching and narrowing of the fluorescence are observed. In such molecules the tunneling between the quantum dots can also induce a dark state. The results are explained by the transition properties of the dressed states generated by the coupling of the laser and the tunneling. Unlike the atomic system, in such quantum dot molecules quantum coherence can be induced using tunneling, requiring no coupling lasers, which will allow tunneling controllable quantum dot molecules to be applied to quantum optics and photonics. (paper)

Fast Arc-Annotated Subsequence Matching in Linear Space

DEFF Research Database (Denmark)

Bille, Philip; Gørtz, Inge Li

2010-01-01

is deleted any arc with an endpoint in that base is also deleted. Arc-annotated strings where the arcs are "nested" are a natural model of RNA molecules that captures both the primary and secondary structure of these. The arc-preserving subsequence problem for nested arc-annotated strings is basic primitive...... for investigating the function of RNA molecules. Gramm et al. [ACM Trans. Algorithms 2006] gave an algorithm for this problem using O(nm) time and space, where m and n are the lengths of P and Q, respectively. In this paper we present; a new algorithm using O(nm) time and O(n+m,) space, thereby matching...... the previous time bound while significantly reducing the space from a quadratic term to linear. This is essential to process large RNA molecules where the space is a likely to be a bottleneck. To obtain our result we introduce several novel ideas which may be of independent interest for related problems on arc...

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon

Science.gov (United States)

Malinina, A. A.; Malinin, A. N.

2015-03-01

Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (λmax = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/ N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10-15 m3/s.

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon

Energy Technology Data Exchange (ETDEWEB)

Malinina, A. A., E-mail: alexandr-malinin@rambler.ru; Malinin, A. N. [Uzhhorod National University (Ukraine)

2015-03-15

Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (λ{sub max} = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10{sup −15} m{sup 3}/s.

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon

International Nuclear Information System (INIS)

Malinina, A. A.; Malinin, A. N.

2015-01-01

Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (λ max = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10 −15 m 3 /s

Analytical method validation of GC-FID for the simultaneous measurement of hydrocarbons (C2-C4) in their gas mixture

OpenAIRE

Oman Zuas; Harry budiman; Muhammad Rizky Mulyana

2016-01-01

An accurate gas chromatography coupled to a flame ionization detector (GC-FID) method was validated for the simultaneous analysis of light hydrocarbons (C2-C4) in their gas mixture. The validation parameters were evaluated based on the ISO/IEC 17025 definition including method selectivity, repeatability, accuracy, linearity, limit of detection (LOD), limit of quantitation (LOQ), and ruggedness. Under the optimum analytical conditions, the analysis of gas mixture revealed that each target comp...

New insights into the microemulsion-based chromatographic NMR resolution mechanism and its application to fragrance/flavor molecules

Science.gov (United States)

Hoffman, Roy E.; Aserin, Abraham; Garti, Nissim

2012-07-01

The NMR chromatography method is applied to a class of molecules with similar physical properties. We correlate the separation ability of microemulsions to the physical properties of the analyzed molecules. Flavor and aroma compounds are very widespread. Compositional analysis is in many cases tedious. Any new method of analysis is always useful and challenging. Here we show a new application to a class of fragrance molecules, with only a moderate variation in their chemical and physical characteristics. Up to 11 selected compounds in one mixture are resolved in one spectrum by NMR chromatography, despite the similarity of the compounds. The differences between O/W and W/O microemulsions and their resolution mechanism as applied to fragrance molecules are explained in terms of hydrophilicity and lipophilicity and effective critical packing parameters of the microemulsions. The observed diffusion rates are shown to correlate with solvation parameters. These results can be used to estimate the diffusion rates of molecules to be separated, allowing selection of the microemulsion or NMR chromatography solvent appropriate for each specific application.

PCR-based detection of a rare linear DNA in cell culture

Directory of Open Access Journals (Sweden)

Saveliev Sergei V.

2002-01-01

Full Text Available The described method allows for detection of rare linear DNA fragments generated during genomic deletions. The predicted limit of the detection is one DNA molecule per 107 or more cells. The method is based on anchor PCR and involves gel separation of the linear DNA fragment and chromosomal DNA before amplification. The detailed chemical structure of the ends of the linear DNA can be defined with the use of additional PCR-based protocols. The method was applied to study the short-lived linear DNA generated during programmed genomic deletions in a ciliate. It can be useful in studies of spontaneous DNA deletions in cell culture or for tracking intracellular modifications at the ends of transfected DNA during gene therapy trials.

PCR-based detection of a rare linear DNA in cell culture.

Science.gov (United States)

Saveliev, Sergei V.

2002-11-11

The described method allows for detection of rare linear DNA fragments generated during genomic deletions. The predicted limit of the detection is one DNA molecule per 10(7) or more cells. The method is based on anchor PCR and involves gel separation of the linear DNA fragment and chromosomal DNA before amplification. The detailed chemical structure of the ends of the linear DNA can be defined with the use of additional PCR-based protocols. The method was applied to study the short-lived linear DNA generated during programmed genomic deletions in a ciliate. It can be useful in studies of spontaneous DNA deletions in cell culture or for tracking intracellular modifications at the ends of transfected DNA during gene therapy trials.

The mechanisms associated with the development of hypertension after exposure to lead, mercury species or their mixtures differs with the metal and the mixture ratio.

Science.gov (United States)

Wildemann, Tanja M; Siciliano, Steven D; Weber, Lynn P

2016-01-02

Hypertension is considered to be the most important risk factor for the development of cardiovascular diseases. Beside life-style risk factors, exposure to lead and mercury species are increasingly discussed as potential risk factors. Although there are a few previous studies, the underlying mechanism by which exposure to lead and mercury disturb blood pressure regulation is not currently understood. Potential mechanisms are oxidative stress production, kidney damage and activation of the renin-angiotensin system (RAS), all of which can interact to cause dysregulation of blood pressure. Male rats (Wistar) were exposed to lead, inorganic mercury, methylmercury or two mixtures of all three metals for four weeks through the drinking water. The two mixture ratios were based on ratios of known reference values or environmental exposure from the literature. To investigate the potential mechanism of actions, blood pressure was measured after four weeks and compared to plasma nitrotyrosine or reduced/oxidized glutathione levels in liver as markers for oxidative stress. Plasma renin and angiotensin II levels were used as markers for RAS activation. Finally, kidney function and injury were assessed via urinary and plasma creatinine levels, creatinine clearance and urinary kidney-injury molecule (KIM-1). While exposure to lead by itself increased oxidative stress and kidney damage along with blood pressure, inorganic mercury did not affect blood pressure or any end-point examined. Conversely, methylmercury instead increased RAS activation along with blood pressure. Surprisingly, when administered as mixtures, lead no longer increased oxidative stress or altered kidney function. Moreover, the mixture based on an environmental ratio no longer had an effect on blood pressure, while the reference value ratio still retained an increase in blood pressure. Based on our results, the prominent mechanism of action associated with the development of hypertension seems to be oxidative

A framework for ecological risk assessment of metal mixtures in aquatic systems.

Science.gov (United States)

Nys, Charlotte; Van Regenmortel, Tina; Janssen, Colin R; Oorts, Koen; Smolders, Erik; De Schamphelaere, Karel A C

2018-03-01

Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. We combined existing data on chronic metal mixture toxicity at the species level with species sensitivity distribution (SSD)-based in silico metal mixture risk predictions at the community level for mixtures of Ni, Zn, Cu, Cd, and Pb, to develop a tiered risk assessment scheme for metal mixtures in freshwater. Generally, independent action (IA) predicts chronic metal mixture toxicity at the species level most accurately, whereas concentration addition (CA) is the most conservative model. Mixture effects are noninteractive in 69% (IA) and 44% (CA) and antagonistic in 15% (IA) and 51% (CA) of the experiments, whereas synergisms are only observed in 15% (IA) and 5% (CA) of the experiments. At low effect sizes (∼ 10% mixture effect), CA overestimates metal mixture toxicity at the species level by 1.2-fold (i.e., the mixture interaction factor [MIF]; median). Species, metal presence, or number of metals does not significantly affect the MIF. To predict metal mixture risk at the community level, bioavailability-normalization procedures were combined with CA or IA using SSD techniques in 4 different methods, which were compared using environmental monitoring data of a European river basin (the Dommel, The Netherlands). We found that the simplest method, in which CA is directly applied to the SSD (CA SSD ), is also the most conservative method. The CA SSD has median margins of safety (MoS) of 1.1 and 1.2 respectively for binary mixtures compared with the theoretically more consistent methods of applying CA or IA to the dose-response curve of each species individually prior to estimating the fraction of affected species (CA DRC or IA DRC ). The MoS increases linearly with an increasing number of metals, up to 1.4 and 1.7 for quinary mixtures (median) compared with CA DRC and IA DRC

Tunnel current across linear homocatenated germanium chains

International Nuclear Information System (INIS)

Matsuura, Yukihito

2014-01-01

The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended σ-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant β, which is defined as e −βL , of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge–Ge bond length is longer than the Si–Si bond length

Cooperative Effects of Zwitterionic-Ionic Surfactant Mixtures on the Interfacial Water Structure Revealed by Sum Frequency Generation Vibrational Spectroscopy.

Science.gov (United States)

Pan, Xuecong; Yang, Fangyuan; Chen, Shunli; Zhu, Xuefeng; Wang, Chuanyi

2018-05-08

Cooperative effects of a series of equimolar binary zwitterionic-ionic surfactant mixtures on the interfacial water structure at the air-water interfaces have been studied by sum frequency generation vibrational spectroscopy (SFG-VS). For zwitterionic surfactant palmityl sulfobetaine (SNC 16 ), anionic surfactant sodium hexadecyl sulfate (SHS), and cationic surfactant cetyltrimethylammonium bromide (CTAB) with the same length of alkyl chain, significantly enhanced ordering of interfacial water molecules was observed for the zwitterionic-anionic surfactant mixtures SNC 16 -SHS, indicating that SNC 16 interacts more strongly with SHS than with CTAB because of the strong headgroup-headgroup electrostatic attraction for SNC 16 -SHS. Meanwhile, the SFG amplitude ratio of methyl and methylene symmetric stretching modes was used to verify the stronger interaction between SNC 16 and SHS. The conformational order indicator increased from 0.64 for SNC 16 to 7.17 for SNC 16 -SHS but only 0.94 for SNC 16 -CTAB. In addition, another anionic surfactant sodium dodecyl sulfate (SDS) was introduced to study the influence of chain-chain interaction. Decreased SFG amplitude of interfacial water molecules for SNC 16 -SDS was observed. Therefore, both the headgroup-headgroup electrostatic interaction and chain-chain van der Waals attractive interaction of the surfactants play an important role in enhancing the ordering of interfacial water molecules. The results provided experimental and theoretical bases for practical applications of the surfactants.

Application of fuzzy logic to determine the odour intensity of model gas mixtures using electronic nose

Science.gov (United States)

Szulczyński, Bartosz; Gębicki, Jacek; Namieśnik, Jacek

2018-01-01

The paper presents the possibility of application of fuzzy logic to determine the odour intensity of model, ternary gas mixtures (α-pinene, toluene and triethylamine) using electronic nose prototype. The results obtained using fuzzy logic algorithms were compared with the values obtained using multiple linear regression (MLR) model and sensory analysis. As the results of the studies, it was found the electronic nose prototype along with the fuzzy logic pattern recognition system can be successfully used to estimate the odour intensity of tested gas mixtures. The correctness of the results obtained using fuzzy logic was equal to 68%.

Chemical-physical characterization of a binary mixture made of a photosensitive azobenzene derivative and a smectogen

Czech Academy of Sciences Publication Activity Database

Borello, E.; Cifelli, M.; Duce, C.; Galli, G.; Tine, M.R.; Hamplová, Věra; Ambrozic, G.; Domenici, V.

2015-01-01

Roč. 614, č. 1 (2015), s. 54-61 ISSN 1542-1406 R&D Projects: GA ČR GA13-14133S; GA MŠk(CZ) 7AMB14PL035 Grant - others:AVČR(CZ) M100101204; AVČR(CZ) M100101211 Institutional support: RVO:68378271 Keywords : liquid crystalline mixture * nematic * smectic A * photosensitive molecules * DSC * 2HNMR Subject RIV: CC - Organic Chemistry Impact factor: 0.532, year: 2015

Thermodynamic and morphological analysis of eutectic formation of CBZ-L-Asp and L-PheOMe.HCl mixtures

International Nuclear Information System (INIS)

Kim, Hyun Jung; Kim, Jong Hoon; Youn, Sung Hun; Shin, Chul Soo

2006-01-01

The eutectic melting of a CBZ-L-Asp/L-PheOMe.HCl model mixture was investigated in kinetic, thermal, thermodynamic, rheological, and morphological aspects. From TX-phase diagrams, the eutectic composition was determined to be 0.55 M fraction of CBZ-L-Asp. The highest melting rate and the lowest apparent viscosity in the range of 55-75 deg. C were obtained at the eutectic composition. Using Arrhenius plots of melting rates and apparent viscosities, minimum activation energies in the range of 60-80 deg. C were obtained at the eutectic composition, whereas maximum values were attained below 60 deg. C. At the eutectic composition, the maximum heat of fusion, the lowest excess free energy, and the highest excess entropy values were observed by differential scanning calorimetry (DSC). A highly homogeneous morphology due to rearrangement of molecules was observed in the eutectic mixture via scanning electron microscopy and X-ray diffraction analysis. IR spectra revealed that hydrogen bonding in the mixture increases during eutectic melting

Non-linear osmosis

Science.gov (United States)

Diamond, Jared M.

1966-01-01

1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall-bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes. 2. As in many other tissues, water flow was found to vary with gradient in a markedly non-linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow. 3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186-825 m-osM. 4. The resistance to water flow was the same when the gall-bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities. 5. Of the theories advanced to explain non-linear osmosis in other tissues, flow-induced membrane deformations, unstirred layers, asymmetrical series-membrane effects, and non-osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non-linear osmosis in rabbit gall-bladder is due to a decrease in water permeability with increasing osmolarity. 6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered. PMID:5945254

Detecting high-density ultracold molecules using atom–molecule collision

International Nuclear Information System (INIS)

Chen, Jun-Ren; Kao, Cheng-Yang; Chen, Hung-Bin; Liu, Yi-Wei

2013-01-01

Utilizing single-photon photoassociation, we have achieved ultracold rubidium molecules with a high number density that provides a new efficient approach toward molecular quantum degeneracy. A new detection mechanism for ultracold molecules utilizing inelastic atom–molecule collision is demonstrated. The resonant coupling effect on the formation of the X 1 Σ + g ground state 85 Rb 2 allows for a sufficient number of more deeply bound ultracold molecules, which induced an additional trap loss and heating of the co-existing atoms owing to the inelastic atom–molecule collision. Therefore, after the photoassociation process, the ultracold molecules can be investigated using the absorption image of the ultracold rubidium atoms mixed with the molecules in a crossed optical dipole trap. The existence of the ultracold molecules was then verified, and the amount of accumulated molecules was measured. This method detects the final produced ultracold molecules, and hence is distinct from the conventional trap loss experiment, which is used to study the association resonance. It is composed of measurements of the time evolution of an atomic cloud and a decay model, by which the number density of the ultracold 85 Rb 2 molecules in the optical trap was estimated to be >5.2 × 10 11 cm −3 . (paper)

Parental exposure to natural mixtures of POPs reduced embryo production and altered gene transcription in zebrafish embryos.

Science.gov (United States)

Lyche, Jan L; Grześ, Irena M; Karlsson, Camilla; Nourizadeh-Lillabadi, Rasoul; Berg, Vidar; Kristoffersen, Anja B; Skåre, Janneche U; Alestrøm, Peter; Ropstad, Erik

2013-01-15

Determination of toxicity of complex mixtures has been proposed to be one of the most important challenges for modern toxicology. In this study we performed genome wide transcriptome profiling to assess potential toxicant induced changes in gene regulation in zebrafish embryos following parental exposure to two natural mixtures of persistent organic pollutants (POPs). The mixtures used were extracted from burbot (Lota lota) liver originating from two lakes (Lake Mjøsa and Lake Losna) belonging to the same freshwater system in Norway. The dominating groups of contaminants were polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane metabolites (DDTs). Because both mixtures used in the present study induced similar effects, it is likely that the same toxicants are involved. The Mjøsa mixture contains high levels of PBDEs while this group of pollutants is low in the Losna mixture. However, both mixtures contain substantial concentrations of PCB and DDT suggesting these contaminants as the predominant contributors to the toxicity observed. The observed effects included phenotypic traits, like embryo production and survival, and gene transcription changes corresponding with disease and biological functions such as cancer, reproductive system disease, cardiovascular disease, lipid and protein metabolism, small molecule biochemistry and cell cycle. The changes in gene transcription included genes regulated by HNF4A, insulin, LH, FSH and NF-κB which are known to be central regulators of endocrine signaling, metabolism, metabolic homeostasis, immune functions, cancer development and reproduction. The results suggest that relative low concentrations of the natural mixtures of POPs used in the present study might pose a threat to wild freshwater fish living in the lakes from which the POPs mixtures originated. Copyright © 2012 Elsevier B.V. All rights reserved.

Non-Linear MDT Drift Gases like Ar/CO2

CERN Document Server

Aleksa, Martin

1998-01-01

Detailed measurements and simulations have been performed, investigating the properties of Ar/CO2 mixtures as a MDT drift gas. This note presents these measurements and compares them to other drift gases that have been simulated using GARFIELD, HEED and MAGBOLTZ.This note also describes systematic errors to be considered in the operation of precision drift chambers using such gases. In particular we analyze effects of background rate variations, gas-density changes, variations of the gas composition, autocalibration, magnetic field differences and non-concentricity of the wire. Their impact on the reconstructed muon momentum resolution was simulated with DICE/ATRECON.The different properties of linear and non-linear drift gases and their relative advantages and disadvantages are discussed in detail.

Properties of LiBF4 and LiAsF6 solutions in mixtures of tetrahydrofuran and 2-methyltetrahydrofuran

International Nuclear Information System (INIS)

Plakhotnik, A.V.; Tovmash, N.F.; Mishustin, A.I.; Kokunov, Yu.V.

1993-01-01

Solutions of lithium tetrafluoroborate and hexafluoroarsenate in mixtures of tetrahydrofuran and 2-methyltetrahydrofuran were studies by the methods of conductometry, densimetry, viscosimetry and measurement of spin-lattice relaxation rate on 7 Li nuclei. Considerable ifluence of anion nature was ascertained. Assumptions are made on the presence of cooperative interaction involving formation of the structures from solvent molecules and salt ions

Dependence of energy per molecule on sputtering yields with reactive gas cluster ions

International Nuclear Information System (INIS)

Toyoda, Noriaki; Yamada, Isao

2010-01-01

Gas cluster ions show dense energy deposition on a target surface, which result in the enhancement of chemical reactions. In reactive sputtering with gas cluster ions, the energy per atom or molecule plays an important role. In this study, the average cluster size (N, the number of atoms or molecules in a cluster ion) was controlled; thereby the dependences of the energy per molecule on the sputtering yields of carbon by CO 2 cluster ions and that of Si by SF 6 /Ar mixed gas cluster ions were investigated. Large CO 2 cluster ions with energy per molecule of 1 eV showed high reactive sputtering yield of an amorphous carbon film. However, these ions did not cause the formation of large craters on a graphite surface. It is possible to achieve very low damage etching by controlling the energy per molecule of reactive cluster ions. Further, in the case of SF 6 /Ar mixed cluster ions, it was found that reactive sputtering was enhanced when a small amount of SF 6 gas (∼10%) was mixed with Ar. The reactive sputtering yield of Si by one SF 6 molecule linearly increased with the energy per molecule.

Giant Magnetoresistance in Carbon Nanotubes with Single-Molecule Magnets TbPc2.

Science.gov (United States)

Krainov, Igor V; Klier, Janina; Dmitriev, Alexander P; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang; Gornyi, Igor V

2017-07-25

We present experimental results and a theoretical model for the gate-controlled spin-valve effect in carbon nanotubes with side-attached single-molecule magnets TbPc 2 (Terbium(III) bis-phthalocyanine). These structures show a giant magnetoresistance up to 1000% in experiments on single-wall nanotubes that are tunnel-coupled to the leads. The proposed theoretical model combines the spin-dependent Fano effect with Coulomb blockade and predicts a spin-spin interaction between the TbPc 2 molecules, mediated by conducting electrons via the charging effect. This gate-tuned interaction is responsible for the stable magnetic ordering of the inner spins of the molecules in the absence of magnetic field. In the case of antiferromagnetic arrangement, electrons with either spin experience the scattering by the molecules, which results in blocking the linear transport. In strong magnetic fields, the Zeeman energy exceeds the effective antiferromagnetic coupling and one species of electrons is not scattered by molecules, which leads to a much lower total resistance at the resonant values of gate voltage, and hence to a supramolecular spin-valve effect.

Fabrication of Low Noise Borosilicate Glass Nanopores for Single Molecule Sensing.

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Jayesh A Bafna

Full Text Available We show low-cost fabrication and characterization of borosilicate glass nanopores for single molecule sensing. Nanopores with diameters of ~100 nm were fabricated in borosilicate glass capillaries using laser assisted glass puller. We further achieve controlled reduction and nanometer-size control in pore diameter by sculpting them under constant electron beam exposure. We successfully fabricate pore diameters down to 6 nm. We next show electrical characterization and low-noise behavior of these borosilicate nanopores and compare their taper geometries. We show, for the first time, a comprehensive characterization of glass nanopore conductance across six-orders of magnitude (1M-1μM of salt conditions, highlighting the role of buffer conditions. Finally, we demonstrate single molecule sensing capabilities of these devices with real-time translocation experiments of individual λ-DNA molecules. We observe distinct current blockage signatures of linear as well as folded DNA molecules as they undergo voltage-driven translocation through the glass nanopores. We find increased signal to noise for single molecule detection for higher trans-nanopore driving voltages. We propose these nanopores will expand the realm of applications for nanopore platform.