bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Dielectric Relaxation in Solutions of 6CHBT in Nonpolar Medium
Authors: Kędziora P. , Jadżyn J. , Hellemans L.
Published: February 2015

The frequency dependence of the nonlinear dielectric increment was studied for benzene solutions of the nematogenic molecule 4-(trans-4'-n-hexylcyclohexyl)isothiocyanatobenzene (C6H13CyHx-Ph-N = C = S, 6CHBT) at 25°C. The increment was induced by a quasi-static electric field of high strength (107 V/m), and its relaxation was detected by an alternating field of low strength (102 V/m) in the fre-quency range 1 MHz-3 GHz. The results are discussed in the framework of Coffey's theory.
Structure and Thermodynamic Properties of Molten Rare Earth-Alkali Chloride Mixtures
Authors: Okamoto Yoshihiro , Ogawa Torn
Published: February 2015

The dependence of the enthalpy of mixing on the structure of molten rare earth-alkali chloride mixtures has been investigated by molecular dynamics simulation. The experimental enthalpy of the mixing with its negative and its dependence on the cation size was qualitatively reproduced. It became clear that the enthalpy of mixing depends on the structural features of short and medium range.
Al3+ Coordination in Cryolitic Melts: A Computer Simulation Study
Authors: Castiglione Michael J. , Ribeiro Mauro C. C. , Wilson Mark , Madden Paul A.
Published: February 2015

The structures of melts containing cryolite have proved difficult to confirm, despite decades of study, on account of the high temperatures and corrosiveness of these melts. Raman spectroscopy has so far provided the majority of the insight into the aluminium coordination environments, but some of its interpretations are still debated.

In this paper we present the results of MD simulations on various NaF-AlF3 liquid mixtures using published potentials developed for the solid state and published Raman spectra.
Estimation of Lattice Energies of Organic Molecular Crystals by Combination of Experimentally Determined and Quantum- Chemically Calculated Quantities: A New Value for the Lattice Energy of a-Glycine
Authors: Raabe Gerhard
Published: February 2015

A new value for the lattice energy of a-glycine was determined by combination of the experimentally measured heat of sublimation taken from literature and the quantum-chemically calculated energy difference Etot,gp - Etot,cry, where Etot,gp is the total energy of the most stable form of the compound in the gas phase (carboxylic acid) and Etot,cry the total energy of the molecule as it occurs in its crystalline form (betaine). At the highest levels of ab initio theory employed in this study this energy difference is -(28±2) kcal/mol, indicating that older work overestimated this difference significantly. The reason for the overestimation of this energy difference was determined by means of additional ab initio calculations. The lattice energy of -(67±2)kcal/mol obtained using the new value for Etot,gp - Etot,cry is significantly more positive than an older value of -103 kcal/mol frequently cited in the literature.
Collective Bursting in Populations of Intrinsically Nonbursting Neurons
Authors: Blank Daniel A. , Stoop Ruedi
Published: February 2015

We describe a novel type of bursting that we observe in simulations of large recurrent networks of biophysically plausible, intrinsically non-bursting neurons. The mechanism responsible for the bursting is a combination of excitatory feedback received from neighbouring neurons, together with an activity-dependent adaptation mechanism that slows down spiking. During the bursting phases, the firing patterns are not repeated and the lengths of the interburst intervals are varying. We develop a simple phenomenological model that captures most qualitative aspects of the observed collective bursting. We compare the parameter range leading to bursting in the phenomenological model, with parameter estimates from cortical anatomy and physiology, and conjecture that the discovered new type of bursting should also be observable in biological neocortical networks.
Isolated versus Condensed Anion Structure V: X-ray Structure Analysis and 81Br NQR of t-butylammonium tribromocadmate(II)-1/2 water, i-propylammonium tribromocadmate(II), and tris-trimethylammonium heptabromodicadmate(II)
Authors: Ishihara Hideta , Horiuchi Keizo , Dou Shi-qi , Gesing Thorsten M. , Buhl J.-Christian , Paulus Helmut , Svoboda Ingrid , Fuess Hartmut
Published: February 2015

The crystal structures of the condensed bromocadmate anions with chains built of [CdBr3]∞ were de-termined by X-ray structure analysis at 300 K. In addition, the temperature dependence of the 81Br NQR frequencies was observed. [(t-C4H9NH3)CdBr3]2-H2O (1) tallizes with a double Br bridged chain (monoclinic, P2/c, Z = 4, a = 1963.4(8), b 87.7(4), c 1432.1(6) pm, and ß= 110.66(2)°). Six 81Br NQR lines are observed at temperatures between 77 and 330 K. (i-C3H7NH-3)CdBr3 (2) crystalliz-es with a triple Br bridged chain (orthrhombic, Pbca, Z= 8, a = 1975.4(6), b = 1415.8(4), c = 690.1(2) pm). (2) shows three 81Br NQR lines at temperatures between 77 and 193 K. A phase transition occurs at 224 K. The structure of [(CH3)3 NH]3Cd2Br7] (3) was redetermined. (3) consists of a triple Br bridged chain and a discrete [CdBr4] tetrahedron (hexagonal, P63mc, Z= 8, a = 1483.5(2), c = 685.7(5) pm). The structure of (3) is identical to the one reported by Daoud, Perret, and Dusausoy, Acta Crystallogr., B35, 2718 (1979). Three 81Br NQR lines are observed at temperatures between 77 and 243 K.
On the Relativistic Invariance of Maxwell's Equation
Authors: Jefimenko Oleg D.
Published: February 2015

It is common knowledge that Maxwell's electromagnetic equations are invariant under relativistic transformations. However the relativistic invariance of Maxwell's equations has certain heretofore over-looked peculiarities. These peculiarities point out to the need of reexamining the physical significance of some basic electromagnetic formulas and equations.
Third-order Optical Nonlinearities of Higher Fullerene and Carbon Nanotube
Authors: Xie Rui-Hua , Rao Qin
Published: February 2015

Recent theoretical and experimental studies on the third-order optical nonlinearities of higher fullerenes including C70, C76, C84, C86, C90, C94 and C96 are briefly reviewed. The extended Su-Schrieffer-Heeger model is introduced and applied to study the third-order optical nonlinearity of chiral carbon nanotubes (CCN), where the average contribution Γ of one carbon atom to the third-order optical nonlinearity of each CCN is calculated and compared with that of a well characterized polyenic polymer. It is found that (i) the smaller the diameter of a CCN, the larger the average contribution Γ; (ii) the metallic CCN favors larger third-order optical nonlinearity than the semiconducting one; (iii) CCN can compete with the conducting polymer achieving a large third-order optical susceptibility. Also the doping effect on the second-order hyperpolarizability of a tubular fullerene is investigated. It is found that the doping effect increases greatly the magnitude of the second-order hyperpolarizability of tubular fullerene.
Mean Amplitudes of Vibration of the Novel SbF7
2-, BiF7
2- and Dianions
Authors: Baran E. J.
Published: February 2015

Mean amplitudes of vibration of the recently reported pentagonal bipyramidal SbF7
2- and BiF7
2- dianions were calculated from vibrational spectroscopic data, in the temperature range between 0 and 1000 K. The results are briefly discussed and some comparisons with related species are made.
High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)
Authors: Massalska-Arodź M. , Würflinger A. , Büsinga D.
Published: February 2015

DTA measurements of 4-n-butyl-thiocyanobiphenyl (4TCB) and ρ-cyano-ρ’-pentylphenyl-cyclohex-ane (5HCP) have been performed in the temperature range 220 K-390 K and pressures up to 400 MPa. For 4TCP a transition from a crystalline to a liquid crystal phase (probably smectic E) could be detect-ed at higher pressures > 90 MPa. The pressure dependence of the transition temperature has been estab-lished. At pressures lower than 88.7 MPa no transition of SmE into a crystal or into a glass has been found. For 5HCP only the melting curve was observed, in contrast to 5PCH, which displays a liquid crystalline nematic phase.
35NQR Spectra of Substituted N-(phenyl)-2-chloroacetamides
Authors: Gowda B. Thimme , Bhat D. Krishna , Fuess H. , Weiss Al.
Published: February 2015

Fifteen methyl-, nitro-, or mixed substituted N-(phenyl)-2-chloroacetamides were investigated by 35Cl NQR. The temperature dependence of the frequencies of the 3-methylphenyl and 2,6-dimethylphenyl derivatives were studied for the range 77 K<T<300 K. Only one ω C-Cl frequency was observed for the compound with the two exceptions. For N-(2-nitro,4-chlorophenyl)-2-chloroacetamide the observed values of 35.623 and 35.350 MHz were assigned to ω C-Cl and ring C-Cl, whereas the corresponding values are 36.254 and 34.815 MHz for N-(2-methyl, 3-chlorophenyl)-2-chloroacetamide. The experimental frequencies of all compounds have been compared with values estimated from NQR substituent parameters ‘k’ and the frequency of N-(phenyl)-2-chloroacetamide. The agreement is remarkably good with a maximum deviation of 1.64 MHz. Furthermore γ(35Cl) of all compounds has been correlated with Σki, and with the Hammett constants.
Mesophase and Glass Formation in Binary Systems of Caesium and Alkali-Earth Metal Butyrates
Authors: Mirnaya T. A. , Dradrah V. S. , Yaremchuk G. G.
Published: February 2015

The phase diagrams of the binary systems of non-mesomorphic components such as caesium-mag-nesium, caesium-calcium and caesium-barium butyrates have been studied by differential thermal analysis and hot stage polarization microscopy. Smectic liquid crystals are found in some composition ranges of the binaries with calcium and barium butyrates. The liquid crystal appearance in these systems is explained by the exhibition of latent mesomorphism of caesium butyrate. Glasses are obtained in all systems studied, the formation of vitreous optical anisotropic mesophase being revealed only for binary from caesium and barium butyrates.
Ammonium Ions Dynamics in NH4Br-Proton NMR T1 Measurements and Simulations
Authors: Goc R. , Wąsicki J. , Lewicki S.
Published: February 2015

Monte Carlo simulation of correlation functions for ammonium bromide have been carried out and the NMR relaxation times T1 resulting from these functions were calculated. Results of simulations are compared to experimental values of T1 measured in the temperature range 92 K to 292 K.
Tunneling Magnetoresistance in a Two-Layered La2-2xCa1+2xMn2O7Polycrystal
Authors: Zhou Tie-Jun , Yu Z. , Du Y. W.
Published: February 2015

By the sol-gel method, a polycrystal bulk of two-layered La2-2xCa1+2xMn2O7 with x = 0.2 was successfully synthesized. A high sensitive low-field TMR was found at low temperature.
Structure of Sputtered Amorphous Zr-Hf-Si Alloys
Authors: Pojtinger A. , Lamparter P. , Steeb S.
Published: February 2015

Amorphous (Zr,Hf)37Si63 alloys were produced by sputtering. Their total structure factors were determined by X-ray diffraction. Using the methods of isomorphous substitution and Reverse Monte Carlo simulation, the partial pair correlation functions were obtained. The results were compared with the partial functions of amorphous Ti40Si60. In the amorphous alloys under investigation the transition metal -metalloid correlation dominates the short range order.
On a Direct Superconducting Pairing Mechanism
Authors: Böhm Michael C. , Saal Christoph
Published: February 2015

We suggest that superconductivity can be traced back to a first-order interaction between the charge carriers which does not necessarily involve second-order electron-phonon coupling. For small molecular model systems it is demonstrated that the formation of Cooper pairs can lead to an attenuation of the destabilizing influence of the Pauli antisymmetry principle (PAP). We suggest that this attenuation of a fermionic quantum constraint is the driving force for the superconducting transition. Whenever the PAP is activated in single-particle hoppings of electrons, the corresponding moves reduce the electronic derealization; they raise the ensemble energy. The stability of a fermionic system is enhanced with decreasing influence of the PAP. Moves of Cooper pairs are not influenced by any quantum constraint of the intersite type. This behaviour differs from the well-known fermionic constraints. The quantum statistics of Cooper pairs is of a mixed type combining a fermionic on-site and a bosonic intersite behaviour. It coincides with the quantum statistics of so-called hard core bosonic ensembles. In the present work Cooper pair formation has been studied for smaller molecular models. The electronic Hamiltonian employed is of the two-parameter Hubbard-type. The solid state phenomenon superconductivity is correlated with the molecular concepts of “antiaromaticity” and “aromaticity”. Arguments are given which support the present interpretation.
Electrochemical Behavior of Ba2+ at Liquid Metal Cathodes in Molten Chlorides
Authors: Matsumiya Masahiko , Takano Masatoshi , Takagi Ryuzo , Fujita Reiko
Published: February 2015

The electrochemcal behavior of Ba2+ on several liquid metal electrodes (AI, Bi, Cd, Pb, Sn and Zn) in a NaCl-KCl equimolar solvent at 1000 K has been investigated by means of cyclic voltammetry and chronopotentiometry. The kinetic parameters and the diffusion coefficient for Ba2+ were determined by cyclic voltammetry with conventional, semi-integral, semi-differential methods and chronopotentiometry. It was revealed that on a liquid Pb electrode in the NaCl-KC1 system at 1000 K the quasi-reversible cathodic reaction Ba2+ + 2e- + Pb → BaPb takes place. In addition, the kinetic parameters and the diffusion coefficient agree well with the values determined by various electroanalyses. The possibility of alloy formation between Ba and Sn was also demonstrated in this paper.
On the Variable-coefficient Burgers-Hlavaty Equation
Authors: Gao Yi-Tian , Tian Bo
Published: February 2015

We study Hlavaty’s generalization of the Burgers equation containing certain coefficient functions. We obtain a new auto-Bäcklund transformation and a family of exact analytical solutions along with the constraints on those coefficients.
Further Measurements of the Zonar Distribution of 18O in Synthetic Quartz Crystals
Authors: Klemm A. , Roller K. , Hoemes S.
Published: February 2015

The isotop effect δ18OF -δ18Os, measured between the face F and the solvent S of synthetic quartz crystals, grown at 1 kbar and 550-700 K, has been estimated to be 5.4, 18O being enriched in the solid.
A Refined Ionic Model for Clusters Relevant to Molten Chloroaluminates
Authors: Akdeniz Z. , Tosi M. P.
Published: February 2015

A model of ionic interactions in neutral and ionized aluminium trichloride clusters, which accounts for ionic deformability through (i) effective valences and (ii) electrostatic and overlap polarizabilities, is evaluated for applications to classical simulation studies of the pure melt and of molten alkali chloroaluminates. The disposable parameters in the model are determined from the measured values of the bond length in the (AlCl4)- molecular ion and of an Al-Cl bond length and a vibrational frequency in the Al2Cl6 molecular dimer. The model is tested against the remaining available data from experiment and from quantum chemical calculations on molecular bond lengths, bond angles and vibrational frequencies for Al2Cl6 , (AlCl4)- and (Al 2Cl7)-clusters. Structural and dynamical properties are also evaluated for the (Al2Cl5)+ , AlCl3 and (AlCl2)+ clusters. The results for the energetics of dissociation, ion transfer and isomer excitation reactions are compared with as yet unpublished data obtained by P. Ballone in first-principles calculations by a density functional method. The overall quality of the tests supports the approximate validity and transferability of the model.
CP's Triple-bond Strength Experienced in its THz Spectrum
Authors: Klein H. , Klisch E. , Winnewisser G. , Königshofen A. , Hahn J.
Published: February 2015

The submillimeter-wave rotational spectrum of the CP radical in the electronic and vibrational ground state (X2Σ+) was recorded in the frequency region between 572 GHz and 1.05 THz, covering rotational quantum numbers from N = 11 up to 21. The CP radical has been produced by discharging CH4 over red phosphorus buffered with Ar at liquid nitrogen temperature. Analysis of the new rotational data of CP together with those available in the literature allows the derivation of an accurate set of molecular constants, including rotational, B0 = 23859.91521(28) MHz and the centrifugal distortion constant D0 = 39.8140(19) kHz, the fine structure and hyperfine structure parameters. The stiffness of the CP bond can be inferred by requiring only one distortion constant D0 to fit the measured rotational spectrum.
Thermodynamic Properties of Bosons in Symmetric Double-well Potentials
Authors: Choy J. , Liu K. L. , Lo C. F. , So F.
Published: February 2015

We study the thermodynamic properties and the Bose-Einstein condensation (BEC) for a finite num-ber N of identical non-interacting bosons in the field of a deep symmetric double-well potential (SDWP). The temperature dependence of the heat capacity C(T) at low temperatures is analyzed, and we derive several generic results which are valid when the energy difference between the first two excited states is sufficiently large. We also investigate numerically the properties of non-interacting bosons in three-dimensional superpositions of deep quartic SDWP's. At low temperatures, we find that C(T) displays microstructures which are sensitive to the value of N and the thermal variation of the condensate frac-tion shows a characteristic plateau. The origin of these features is discussed, and some general conclu-sions are drawn.
On the Ambiguity of Molecular Complexes Formed by Two Molecules
Authors: Kassi S. , Dreizler H.
Published: February 2015

We present a general consideration how many structural conformers are compatible with one set of rotational constants if one rotational spectrum of a dimer is investigated. A selection of a certain con-former should be guided by the investigation of isotopomers, quantum chemical calculations or other arguments.
Foreign Gas Broadening Studies of the J' ←J = 1← 0 Rotational Line of CO by Frequency and Time Domain Techniques
Authors: Nissen N. , Doose J. , Guarnieri A. , Mäder H. , Markov V. N. , Golubyatnikov G. Yu. , Leonov I.I. , Shanin V. N. , Krupnov A. F.
Published: February 2015

The collisional broadening of the J '← J = 1 ← 0 rotational line of carbon monoxide by the buffer gases He, Ne, Ar, Kr, CO, N2, O2 , and air has been studied at room temperature. Two different experimental techniques in time- and frequency-domain, respectively, were used. The obtained data are in good agreement. Time-domain investigations on the temperature dependence of the foreign gas broadening parameters are also presented.
Heat Capacity of K3LnCl6 Compounds with Ln = La, Ce, Pr, Nd
Authors: Gaune-Escard M. , Rycerz L.
Published: February 2015

The heat capacities of the solid and liquid K3LnCl6 compounds (Ln = La, Ce, Pr, Nd) have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. Their temperature dependence is discussed in terms of the phase transitions of these compounds as reported in literature. The heat capacity increases and decreases strongly in the vicinity of a phase transition but else varies smoothly. The Cp data were fitted by an equation which provides a satisfactory representation up to the temperatures of Cp discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained compare satisfactorily with these experimental data.
High Resolution FTIR Spectrum of Chlorofluoroethyne, FCCCl, Below 1000 Cm—1. Analysis of the υ3, υ4 υ5, 2υ4, υ4 + υ5 and 2υ5 Bands, and ab initio Calculations
Authors: Bürger H. , Senzlober M. , Thiel W. , Breidung J.
Published: February 2015

High resolution infrared spectra of FCCCl have been measured and analyzed by polynomial methods. In the region below 350 cm-1 , the analysis is straightforward and yields parameters for the υ4 = 1 and υ5 = 1 states. Between 350 and 800 cm-1 there are strong anharmonic interactions in the 2υ5/υ4 + υ5/υ3/2υ4 tetrad which have been unravelled with the use of a model that employs ab initio interaction constants. Observed and theoretically predicted wavenumbers are in excellent agreement for all bands studied.
Determination of Multiple Steady States in an Active Membrane Transport Model
Authors: Li Hsing-Ya
Published: February 2015

A necessary and sufficient condition is applied to determine the possibility of multiple positive steady states in a complex, active membrane transport model with a cycle, which is performed by pump pro-teins coupled to a source of metabolic energy. A set of rate constants and two corresponding steady states are computed. Hysteresis phenomena are observed. A signature of multiplicity is derived, which can be applied in mechanism identifications if steady-state concentrations for some species are measured. The bifurcation of multiple steady states is also displayed.
35Cl NQR Spectra of Substituted N-(Phenyl)-2,2,2-Trichloroacetamides
Authors: Gowda B. Thimme , Bhat D. Krishna , Fuess Hartmut , Weiss Alarich
Published: February 2015

Several substituted acetamides, XyC6H5_ y NHCOCCl3 (X=CH3 , NO2 , or Br and y= 1 or 2) have been synthesized and studied by NQR. The effect of ring substitution on the average υ(35Cl) NQR of the trichloroacetyl group is not substantial, but it affects the crystal structure of the substituted com-pounds. The NQR spectra of XyC6H5-y NHCOCCl 3 (where Xy =4-CH3 , 4-NO2 , and 2,3-(CH3)2) show six 35Cl NQR frequencies, each indicating the presence of two molecules in their respective asym-metric units. The temperature dependence of υ(35Cl) NQR of N-(4-methylphenyl)-2,2,2-trichloroacet-amide reveals that it undergoes a first order phase transition around 205 K. Its spectrum shows six lines up to 205 K and three lines thereafter. The latter triplet part of the spectrum fades out around 250 K due to librational motions in the crystal lattice, as the torsional motions of the CCl3 group are easily excit-ed. The 35Cl NQR spectra of all the methylsubstituted amides have been compared with those of the corresponding chlorosubstituted compounds. Generally there is no systematic variation of the mean val-ues of υ(35Cl) NQR or the trichloroacetyl group with the substituents in the phenyl ring. The ω C-Cl frequencies of the trichloroacetyl group of all the v-substituted N-(phenyl)-2,2,2-trichloroacetamides have been estimated using NQR substituent parameters (k) and the frequencies of N-(phenyl)-2,2,2-tri-chloroacetamide. Agreement between these values and the experimental frequencies is quite good. The υ(35Cl) NQR of these amides has also been correlated with Σki of the substituents. Further υ(35Cl) NQR spectra of mono-and trichloroacetamides have been correlated.
Lineshape Analysis of 2D NMR and NQR Nutation Spectra of Integer and Half-Integer Quadrupolar Nuclei
Authors: Velikite N. , Sinyavsky N. , Maćkowiak M.
Published: February 2015

A lineshape analysis of the NMR and NQR powder nutation spectra of integer and half-integer quadrupolar nuclei is presented. Simulated NMR nutation spectra of spin I = 1 and 3 nuclei are reported. For I = 1 the formulas for the singularities of the NMR nutation powder patterns as a functions of η, e2Qq and 7B x are given. The NQR nutation powder patterns for spin I = 3/2, 5/2, 7/2, and 9/2 for different induced transitions are calculated, and some experimental aspects of the method are discussed. A universal empirical formula to facilitate the determination of the asymmetry parameter from the NQR nutation frequency singularities for any arbitrary spin or transition is found. The NQR nutation spectra for half-integer and integer spins are compared. For integer spins the two-frequency excitation of the nutation spectrum is analysed. Application of the 2D-nutation lineshape analysis for the determination of the quadrupole interaction parameters is emphasised.
New Mechanism for Facile Charge Transport in Polypeptides
Authors: Baranov L. Ya. , Schlag E. W.
Published: February 2015

An electronic hole migration accross a polypeptide chain is discussed with special reference to new ab initio computational results and to the experimental observations of Weinkauf et al. on the charge photoinjection into the polypeptide backbone. New mechanistic details for this efficient charge transport process are proposed. The process is viewed as a vibronically induced hole hopping between local aminoacid sites driven by large amplitude torsional motions of the floppy backbone.
Local Correlation's Potential for Noise Reduction and Symbolic Partitions
Authors: Kern A. , Steeb W.-H. , Stoop R.
Published: February 2015

We investigate local correlation dimension-based noise-cleaning of time series, where points having anomalously large dimensions are iteratively removed from the reconstructed attractor. We find an optimal range for the number of iterations in which the algorithm yields good results. Choosing non-local ranges for the linear regression yields a new method for finding nonhyperbolic tangency points. The method is also applicable for noisy systems with unknown dynamics; in this case, noise facilitates the detection of the points.
Nuclear Quadrupole Interactions in Cadmium Complexes: Semiempirical and ab initio Calculations
Authors: Hemmingsen Lars , Ryde Ulf , Bauer Rogert
Published: February 2015

Semiempirical calculations, based on the so-called angular overlap model, have been compared with ab initio methods (MP2) for the calculation of nuclear quadrupole interactions (NQI’s) in cadmium complexes with biologically relevant ligands (H2O, OH-, cysteinate, carboxylate, and imidazole). The assumptions on which the semiempirical model is based have been tested and the comparison indicates that: 1) A change in the Cd-ligand bond length by 0.1 A may change the electric field gradient (EFG) by about 0.2 a. u.. A simple scheme to incorporate such effects in the semiempirical method is suggested. 2) The effect of ligand-ligand interactions is up to about 0.2 a. u. for the largest diagonal element of the EFG tensor for the tested complexes, and such effects can significantly influence the so-called asymmetry parameter. 3) The position of non-coordinating atoms on the ligands can in some cases (e. g. the hydrogen atoms of water) significantly influence the EFG. The combined effect of non-coordinating atoms and ligand-ligand interactions may cause deviations of up to 0.35 a.u. between ab initio and the semiempirical calculations. 4) In the semiempirical model each ligand is characterised by one parameter, the so-called partial nuclear quadrupole interaction. This parameter has been evaluated by ab initio calculations, and agreement was found within about 0.2 a. u. (≈ 40 Mrad/s) for all ligands except imidazole. 5) A change in the coordination number from 2 to 6 may change the partial NQI by about 0.3 a. u.
The Physical and Molecular Properties of New Low Melting Nematics with Negative Dielectric Anisotropy
Authors: Dąbrowski R. , Jadżyna J. , Dziaduszek J. , Stolarz Z. , Czechowski G. , Kasprzyk M.
Published: February 2015

The paper presents some basic physical properties (static electric permittivities, refraction indices, density and viscosity) of 2-chloro-4-n’-alkylphenyl esters of 4-n-alkylbicyclo[2,2,2] octane-1-carboxylic acids (n’=7, n = 5 and 7) which are, at room temperature, nematics with a negative dielectric an-isotropy. On the basis of temperature dependence of the principal static permittivities ε‖(T) and e⊥(T) of the nematics, using the Maier-Meier equations, the angle between the dipole moment vector and the long axis of mesogenic molecules, the apparent molecular dipole moment square pl μ2
app(T), and the nematic order parameter S(T) were determined.
High Pressure Dielectric Studies of a Substance with the Smectic A1 Phase
Authors: Urban Stanisław , Würflinger Albert
Published: February 2015

The results of dielectric studies of 5-n-hexyl-2-(4'-isothiocyanato)-l,3-dioxane (6DBT) in the smectic A, phase at pressures up to 150 MPa and temperatures up to 340 K are presented. The low frequen-cy relaxation time τ|| (p, T) yields the activation volume Δ# V|| = RT(∂|| In τ||/p)T and activation enthalpy Δ# H|| = R(∂In τ||/∂T-1)p. The calculated values of these parameters are compared with those ob-tained recently for n-octyl-cyanobiphenyl (8CB) forming the smectic Ad phase. In the case of 6DBT both these quantities are practically constant, whereas those for 8CB decrease, when going away from the phase transitions isotropic -smectic A1 (6DBT) or nematic -smectic Ad (8CB). These differences support our earlier conclusion that increase of pressure leads to a breaking of the antiparallel associa-tions of cyanobiphenyl molecules in the smectic as well as in the nematic phases.
Laser Ignition of an Isentropically Compressed Dense Z-Pinch
Authors: Winterberg F.
Published: February 2015

A dense z-pinch generated by a high voltage discharge over a corrugated helical sawtooth-shaped capillary tube with a solid DT core, is by shear flow stabilized against the m = 0 and m= 1 magnetohydrodynamic instabilities, and by rotational flow against the Rayleigh-Taylor instability. The shear-and rotational flow result from jet formation by the corrugated surface. A programmed voltage pulse can then isentropically compress the DT core to high densities, and if ignited at one end by a petawatt laser pulse, a thermonuclear detonation wave can be launched propagating along the z-pinch channel. The proposed z-pinch burn should also work without tritium as a thermonuclear detonation wave in deuterium.
Investigations on a Universal Relationship Between Optical Emission and Absorption of Complex Molecules in Liquid Solutions
Authors: Kawski A. , Bojarski P. , Kukliński B.
Published: February 2015

Based on a universal relationship between the extinction coefficient and the fluorescence intensity in their overlapping region, local temperatures T* higher than the ambient T were determined for short-lived luminescent molecules of lifetimes from 7 ps to 77 ps. The reason for such a local temperature T*, which holds also during the emission process, is the non-establishment of statistical equilibrium over the vibrational levels of excited molecules. It is found that the intensity distribution in the fluorescence band depends slightly on the wavelength of the excitating light, which evidences the lack of thermal equilibrium with the vicinal surrounding.
Some Aspects of General Relativistic Vortex Dynamics and Ertel's Identity
Authors: Schröder Wilfried , Treder Hans-Jürgen
Published: February 2015

According to Erters identity and Ertel's vorticity theorem some aspects on general relativistic vortex dynamics and relationships are discussed in detail.
Molecular Motion in Tetraphenyltin Studied by NMR
Authors: Pajzderska A. , Wąsicki J. , Lewicki S.
Published: February 2015

NMR second moment and spin-lattice relaxation times in the laboratory (60 and 25 MHz) and in the

rotating frame (B1 = 2.1 mT) were studied for polycrystalline tetraphenyltin Sn(C6H5)4 in a wide temperature
range. Two kinds of motions were detected: isotropic rotation of whole molecules and reorientations/
oscillations of phenyl rings. A dependence of the potential energy of the molecule in the crystal
on the angle of the phenyl ring rotation about the Sn-C bond was obtained on the basis of atom-atom
calculations. The amplitude of the ring-oscillations at 133 K was estimated as ± 7°. Below room temperature
the magnetisation recovery is significantly non-exponential, which may be interpreted as due
to the correlated motion of phenyl rings.
Conformational Stability and Structural Determination of Vinyldichlorosilane by ab initio Calculations
Authors: Qtaitat Mohammad A.
Published: February 2015

The Conformational stability and barriers of interconversion between the eis and gauche conformers of vinyldichlorosilane, CH2CHSiHCl2 , have been studied using ab initio calculations employing the RHF/3-21G* and RHF/6-31G* basis sets. The eis conformer was found to be more stable than the gauche one by 45 cm-1 (539 J/mol) and 140 cm-1 (1.68 kJ/mol) from the RHF/3-21G* and RHF/6-31G* basis sets, respectively. Additionally, the structural parameters of both rotamers have been calculated. These results are compared with results of related molecules.
Mössbauer Spectroscopic Study of Fe2O3 Nanoparticles Dispersed over a Silica Matrix
Authors: Cannas Carla , Concas Giorgio , Musinu Anna , Piccaluga Giorgio , Spano Giorgio
Published: February 2015

A series of Fe2O3 -SiO2 nanocomposites (9 -33 wt% of Fe2O3) has been prepared by a sol-gel method and submitted to thermal treatments at 300 -900 °C. The samples were characterized by X-ray diffraction and Mössbauer Spectroscopy measurements. Superparamagnetic behavior is exhibited by all the samples, indicating that the size of iron oxide grains is in the nanometer range (4-6 nm). Increase of iron content and temperature treatment give rise to a small particle growth, while the spread of sizes around the average value increases with the iron concentration. The Mössbauer spectra, at all the explored compositions, show a very steep increase of the peak width by treatment temperature at 900 °C, indicating the formation of the ferrimagnetic γ-Fe2O3 phase from the antiferromagnetic amorphous Fe2O3 phase, which dominates in the samples treated at lower temperatures. The samples at 28.5% and 33.2%, treated at 900 °C, also show a component of γ-Fe2O3 in the blocked state at room temperature. Moreover, the growth of the particles favours the formation of other oxide phases (α and ε phase) along with the γ phase.
Ionic Dynamics in LiNO2 Studied by 7Li and 15N Solid NMR
Authors: Honda Hisashi , Ishimaru Shin'ich , Ikeda Ryuichi
Published: February 2015

The temperature dependences of 7Li and 15N NMR spin-lattice relaxation times and spectra in LiNO2 were measured in the range 120 K -473 K (m.p.). The 180°-flip motion of NO2-- ions along or perpendicular to the molecular C2 -axis and the self-diffusion of Li+ ions (activation energies of 42 -44 and 100 kJ mol-1 , respectively) were observed in this range. From the comparison of the observed activation parameters with those reported for plastic phases of alkali metal nitrites, a new characteristic of the plastic crystal was obtained.
Local Structure of Europium Sites in Oxide Glasses by Nuclear Gamma Resonance
Authors: Concas Giorgio , Spano Giorgio , Carrada Marzia , Bettinelli Marco , Speghini Adolfo
Published: February 2015

The symmetry and disorder of the Eu3+ site was investigated in some phosphate and borate glasses by means of 151Eu Mössbauer spectroscopy. The quadrupole interaction parameter, which is due to the distortion of the Eu site compared to a cubic symmetry, has been measured together with the asymmetry parameter, which points out the absence of a threefold or fourfold axis of symmetry at the rare earth site. The correlation of the isomer shift with the optical basicity of the glass indicates a covalent component with 6s character in the Eu-O bond. The axial component of the electric field gradient at the Eu site is also correlated with the optical basicity.
Auto-Bäcklund Transformation and Solitary-wave Solutions to Non- integrable Generalized Fifth-order Nonlinear Evolution Equations
Authors: Hong Woo-Pyo , Jung Young-Dae
Published: February 2015

We show that the application of the truncated Painlevé expansion and symbolic computation leads to a new class of analytical solitary-wave solutions to the general fifth-order nonlinear evolution equations which include Lax, Sawada-Kotera (SK), Kaup-Kupershmidt (KK), and Ito equations. Some explicit solitary-wave solutions are presented.
Localized Vibration-Formation by Driving Raman Active Molecular Vibrations
Authors: Huang Qing
Published: February 2015

This paper presents a new approach to localize molecular vi-brations. By analyzing YX2 type molecules we show that lo-calized vibrations can be created if we stimulate a set of the molecule's Raman-active normal modes properly by lasers.
Temperature Independent Isotropic EPR Spectra of [(CH3)4N]2MnCl4 and [(CH3)4N]2FeCl4 Single Crystals
Authors: Köksal F. , Bahadir Ş. , Başaran E. , Yerli Y.
Published: February 2015

Electron paramagnetic resonance of [(CH3)4N]2MnCl4 and [(CH3)4N]2FeCl4 single crystals was studied between 20 and 400 K. The peak-to-peak derivative linewidths of these crystals seem not to change in this temperature interval and approximately 100 mT for [(CH3)4N]2MnCl4 and ~20 mT for [(CH3)4N]2FeCl4 .The spectra were found to be isotropic, with g = 2.0039 for [(CH3)4N]2MnCl4 and g = 2.0042 for [(CH3)4N]2FeCl4 .This temperature independence is attributed to isotropic strong ex-change interactions of Mn2- and Fe2+ nuclei, and it seems that hindered rotation of the MnCl4
2- and FeCl4
2- tetrahedra does not occur in this temperature interval.
On Diffusion in Some Biological and Economic Systems
Authors: Ahmed E. , Hassanb S. Z.
Published: February 2015

It is argued that diffusion in biological and economical systems is better modelled by Cattaneo's equation where memory effects are included. Reaction diffusion equations using Cattaneo's system are derived for prisoner's dilemma (PD) and hawk-dove (HD) games. Nonlinear wave solutions are derived for them. As expected the asymptotic solution for the PD case is insufficient. Hence a cellular automata motivated by Cattaneo's system is used to show the existence of cooperation in the case of local game.
Calculation of the Proton Affinities of Primary, Secondary, and Tertiary Amines Using Semiempirical and ab initio Methods
Authors: Raabe Gerhard , Wang Yuekui , Fleischhauer Jörg
Published: February 2015

The proton affinities of some primary, secondary, and tertiary amines have been calculated with different semiempirical and nonempirical quantum chemical methods. We were particularly interested in the question which of the most popular semiempirical methods yield good overall correlations between calculated and experimental values and, therefore, allow a reliable prediction of hitherto unknown proton affinities. We found that some of the most frequently used semiempirical methods result in good correlations only within the groups of primary, secondary and tertiary amines, while the overall correlation is even worse than the one obtained with the noniterative EHT method. Among the more recent methods which allow geometry optimizations (MINDO/3, MNDO, AMI, PM3, MSINDO) the best results have been calculated with the MSINDO method. Testing for the influence of geometry optimization we surprisingly found that two of these methods (MINDO/3, AMI) perform even better when geometry optimizations are omitted and standard bonding parameters are used instead. Superior results, however, have been obtained with the CNDO/2- and the INDO method. Finally, the best correlations between semiempirically calculated and experimental proton affinities have been achieved with the spectroscopic parametrizations of these methods, CNDO/2S and INDO/2S, respectively. The correlations resulting in these cases are close to those reached at the ZPE+MP2/6-31 l++G**//HF/6-311++G** level of ab initio theory and with a comparable DFT method. A preliminary investigation revealed that an improvement in the semiempirical calculation of proton affinities might be obtained if different Uμμ parameters are used for the nitrogen atoms of primary, secondary, and tertiary amines.
Observation of Carbonyl Fluoride, Ketene, Acetic Acid and Fluorocarbene Produced by an Electric Discharge within a Nozzle by Molecular Beam Fourier Transform Microwave Spectroscopy. A Reaction via a Cycloaddition for Carbonyl Fluoride and Keten?
Authors: Sutter D. H. , Dreizler H.
Published: February 2015

A molecular beam Fourier transform microwave spectrometer, designed for the study of chemical reactions within electrical discharges, is described in detail. Applications include the production of carbonyl fluoride, ketene, acetic acid, and difluorocarbene. For the production of carbonyl fluoride and ketene with 1,1-difluoroethylene and carbon dioxide as precursor molecules a reaction path via a 2+2 cycloaddition is proposed.
Cl NQR Spectra of N-(substitutedphenyl)-2,2-dichloroacetamides and Correlation of 35 Cl NQR γCl(ω) of Substituted N-Phenyl- Chloroacetamides XyC6H5-yNHCOR (X = Cl or CH3 , y = 1 or 2, R = CH2Cl, CHCl2 or CCl3)
Authors: Thimme Gowda B. , Arun Kumar B. H. , Fuess Hartmut
Published: February 2015

To study the effect of electron donating or repelling group substitution in the phenyl ring on the γ(35 Cl NQR of Cl(ω)) of the dichloroacetyl group, several N-(methylsubstituted-phenyl)-2,2-dichloroacetamides have been synthesised, characterised and their 35 Cl NQR frequencies mea-sured at 77 K. All the substituted amides, except N-(2,5-dimethylphenyl)-2,2-dichloro-acetamide, show two ω-C-Cl frequencies in the range of 37.009 -38.014 MHz. N-(2,5-dimethylphenyl)-2,2-dichloroacetamide shows one u-C-C 1 NQR frequency at 37.50 MHz for the two chlorine atoms present. The two atoms may be crystallographically equivalent. The frequencies of all the methyl-substituted dichloroacetamides have been compared and correlated alongwith the corresponding chloro substituted-phenyl dichloroacetamides. The γ(35 C1 NQR) of Cl(ω) of all the N-(substituted-phenyl)-2,2-dichloroacetamides have been correlated with the NQR substituent parameters (κi), assuming additivity of the substituent effects. The frequencies are also correlated with Hammett a. The effect of ring substitution on the average 35 Cl NQR Cl(ω) frequencies of the dichloroacetyl group is not substantial, but it affects the crystal structures of the substituted compounds. Using the Ki values for various groups and ω-C-Cl NQR frequencies of N-(phenyl)-2,2-dichloroacetamide (37.195 and 37.596 MHz), 7(35 C1 NQR) of all the N-(methyl and chlorosubstitutedphenyl)-2,2-dichloroacetamides have been estimated. Similar calculations are extended to all the N-(methyl and chlorosubstitutedphenyl)-2-chloroacetamides and -2,2,2-trichloroacetamides. There is a rea-sonably good agreement between the computed and the experimental values for all the three groups of compounds. Further, γ(35 Cl NQR of Cl(ω) of all the substituted N-phenyl-chloroacetamides represented by the general formula XyC6H5- y NHCOR (where X = Cl, or CH3 , y = 1 or 2 and R = CH 2 Cl, CHCl2 or CCl3) are compared. The γ(35Cl NQR of Cl(ω)) of the substituted N-(phenyl)-2,2-dichloroacetamides lie between the frequencies of the corresponding substituted N-(phenyl)-2-chloroacetamides and substituted N-(phenyl)-2,2,2-trichloroacetamides.
Electron Paramagnetic Resonance Study of Cu 2+ in CdCa (CH3COO) 4 • 6H2O Single Crystal
Authors: Kalkan Hüsey in , Senel Ismet
Published: February 2015

The Electron Paramagnetic Resonance spectra of Cu 2+ in CdCa (CH3COO)4 • 6H2O (cadmium calcium tetraacetate hexahydrate) powder and single crystal have been recorded at 300 and 133 K. The angular variation of the spectra indicated the substitution of the host Cd 2+ with Cu 2+ . The observed values of the g and A hyperfine tensors were found to be temperature dependent, and this dependence is discussed and explained on the basis of dynamic Jahn-Teller effects. The spin-Hamiltonian parameters were found to be axial symmetric at room temperature, whereas they showed deviations from axial symmetry at low temperature. The g and A tensors where found to be coaxial within the limits of experimental errors, and the ground state wave functions of the complex at 300 and 133 K have been constructed.
Oxygen-17 Nuclear Magnetic Resonance of Organic Solids
Authors: Dong Shuan , Yamada Kazuhiko , Wu Gang
Published: February 2015

We report solid-state 17O NMR determinations of the oxygen chemical shift (CS) and electric field gradient (EFG) tensors for a series of 17O-enriched organic compounds containing various functional groups. In several cases, analysis of the n O magic-angle-spinning (MAS) and static NMR spectra yields both the magnitude and relative orientations of the 17O CS and EFG tensors. We also demonstrate the feasibility of solid-state 17O NMR as a potentially useful technique for studying molecular structure and hydrogen bonding.
Quadrupole Interaction of 172Yb and 168Er Nuclei in the First Excited 2+ State
Authors: Królas K. , Rams M. , Wojtkowska J.
Published: February 2015

We have measured the hyperfine interactions in YbVO4 and YbPO4 using 172Yb perturbed angular correlation spectroscopy for 90 -1094 keV and 1094 -79 keV γ-γ cascades. The quadrupole interaction frequency varied with temperature from 0 to 2 GHz. Precise information was obtained from both cascades independently even using the cascade with the intermediate state of the half life as short as 1.6 ns.
Hyperfine Interactions at 181Ta in Hf2Ni7 and Zr2Ni7
Authors: Marszałek M. , Saitovitch H. , Silva P. R. J.
Published: February 2015

We report on a time differential perturbed angular correlations (TDPAC) study of the hyperfine interactions at 181Ta in Hf2Ni7 and Zr2Ni7. The samples were prepared by arc melting proper amounts of constituents together with a small amount of Hf containing radioactive 181Hf atoms. A further heat treatment was necessary to obtain samples of the required crystal structure (monoclinic symmetry in the C2/m space group). As known, two non-equivalent lattice sites of Hf/Zr metal exist in this structure.

The PAC measurements were performed at 20 - 1123 K. Two quadrupole interactions were observed, corresponding to two possible crystallographic positions of the probe atom in the studied structure. The electric quadrupole interaction parameters at 181Ta in Hf2Ni7 are υQ1(300K) = 586.7(65) MHz with η1 = 0.79(4) and υQ2(300K) = 466.8(41) MHz with η2 = 0.20(3), and in Zr2Ni7 they are υQ1(300K) = 498.4(22) MHz with η1 = 1.0 and υQ2(300K) = 418.0(50) MHz with η2 = 0.35(3). The presence of a magnetic interaction, reported in the literature, was not confirmed.
Spin Diffusion in Pure Multiple-Pulse NQR
Authors: Furman G. B. , Goren S. D. , Panich A. M. , Shames A. I.
Published: February 2015

We present a detailed theoretical and experimental NQR multiple-pulse spin-locking study of spin-lattice relaxation and spin diffusion processes in the presence of paramagnetic impurities in solids. The obtained diffusion equation was obtained allows to find the time dependence of the magnetization in the effective field. The spin lattice relaxation times were calculated, both for direct and diffusion regimes, as functions of the correlation time and multiple-pulse parameters. Measurements of relaxation times in rotating frame allow to determine the diffusion coefficient and the radius of the diffusion barrier in γ-irradiated polycrystalline samples of NaCIO3.
Optimization of NQR Pulse Parameters using Feedback Control
Authors: Schiano J. L. , Blauch A. J. , Ginsberg M. D.
Published: February 2015

A new method for increasing the probability of detecting nuclear resonance signals is demon-strated experimentally. It is well known that the detection of signals with a low signal to noise ratio (SNR) results in missed detections of false alarms. In situations where the noise is correlated or where limited data is averaging, it may not be possible to achieve a desired SNR through averaging alone. We present an alternative approach in which a feedback algorithm automatically adjusts pulse parameters so that the SNR and probability of correct detection are increased. Experimental results are presented for the detection of 14N NQR signals.