bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscous Properties and Dynamic Electrooptical Performance in Twisted Nematic Displays of Several Liquid Crystal Classes
Authors: Gerber Paul R. , Schadt M.
Published: February 2015

The temperature dependence of the rotational viscosities of several physically markedly different binary mixtures belonging to ten different liquid crystal classes is measured. An attempt is made to correlate the results with class-specific structural properties such as hydrogenated rings, molecular polarity and structure of flexible side-chains. It is show that the measured small-scale dynamic properties of twist cells compare well with approximative theoretical calculations and experimentially determined class-specific material parameters. For the switching times corresponding to large-scale twist deformations heuristic approximations lead to satisfactory results.
Infrared Band-Shape Studies of Sulphate Glasses
Authors: Sundar H. G. K. , Parthasarathy R. , Rao K. J.
Published: February 2015

IR band-shape analysis has been carried out on the 620 cm-1 deformation band of the sulphate ion in several Na2SO4-K2SO4-ZnSO4 glasses. Variations of correlation times and second moments suggest that reorientational motions of sulphate ions begin to evolve prior to the glass-transition temperature. The correlation times may support a cluster model for the glass-transition.
Measurements of the Fluorescence Decay Time in Mixed Solutions Using Pulse Fluorometery
Authors: Bauer R. K. , Twardowski R.
Published: February 2015

The mean fluorescence decay time for rhodamine 6G (donor) in the presence of malachite green (acceptor) has been investigated using a pulse fluorometer. The experimental results have been compared with theoretical ones obtained earlier [1].
Topological Resonance Energy of Linear Polyaeenes
Authors: Gutman Ivan
Published: February 2015

A method for computation of the topological resonance energy (TRE) of linear polyacenes is described. When the length of the polyacene chain increases, TRE tends to 0.02 β units per π-electron, contrary to a previous prediction [1]. The ionization potential and the energy of the p-band of linear polyacenes are found to be excellently correlated with TRE.
Low Temperature Vibrational Relaxation of Gaseous CF3Cl, CF3Br, CHF2Cl, and CH3Cl
Authors: Kadibelban R. , Ahrens-Botzong R. , Hess P.
Published: February 2015

Ultrasonic absorption measurements are reported for gaseous CF3Cl, CF3Br, CHF2Cl, and CH3Cl between room temperature and the lower temperatures 163 K, 193 K, 198 K, and 213 K, respectively. Starting from a statistical point of view, the relaxation behavior is divided into three classes, which are associated with the positive, zero, and negative slope in a log(k) versus 1/T plot. On this basis the vibrational relaxation behavior of CF4, CF3Cl, CF3Br, CHF3, CHF2Cl, CH3Cl, NF3, PF3, and BF3 is discussed especially in the critical temperature to boiling point region. This temperature region is used as a reference for comparing different molecules.
Absolute Cross Sections for the Chemiluminescent and Chemiionizing Reactions Mg*(3P), Ca*(3P) + SOCl2
Authors: Kowalski Andrzej
Published: February 2015

The absolute cross sections for different electronic exit channels for the reactions Mg*(3P), Ca*(3P) + SOCl2 were measured in a beam-gas experiment. The chemiluminescence and chemiionization yields measured are low (total 2%) but equal or are even higher for some channels than those calculated from a statistical model.
Variational Calculation of the Lower Vibrational Energy Levels of the Ammonia Molecule
Authors: Bopp Philippe , McLaughlin Don R. , Wolfsberg Max
Published: February 2015

A variational calculation of the lower-lying vibrational energy levels of the ammonia molecule is performed, in which all six vibrational degrees of freedom are treated simultaneously. A literature potential is assumed for all non-inversion motions; a new inversion barrier potential with a barrier of 1616 cm-1 is determined by fitting experimental data.
Spherical Wave Treatment of Laue Case Rocking Curves
Authors: Bonse U. , Teworte R.
Published: February 2015

A spherical wave theory is given for the calculation of the observed fine structure of Laue case rocking curves [1 - 3] of a pair of perfect crystals.

It is shown that under the experimental condition of measuring simultaneously the full width of outgoing beams, the simple plane wave theory presented previously [1] yields identical results.
A Geometrical Correction for Precise Lattice Constant Determination
Authors: Bradaczek Hans , Leps Bernd , Uebach Wilhelm
Published: February 2015

A correction term for high precision lattice constant investigations has been derived, which is caused by geometrical and absorption effects. Surprisingly there is no dependence on absorption and extinction in the case of high absorption and/or “infinite” crystal thickness. Only the half width of the rocking curve has to be considered. In the case of low absorption and/or thin crystal, there are terms of higher order which still depend on p.t but can be neglected compared to the main effect.

The main reason for the correction is that the observed rocking curve is the result of a “true” rocking curve multiplied by a geometrical function which is not symmetrical with respect to the rocking angle. For high precision measurements (< 10-5) the application of the correction term is recommended.
X-Ray Extinction Theory in the Bragg Geometry
Authors: Kuriyama M. , Cohen G. G.
Published: February 2015

In view of the renewed interest in surface reflection x-ray topography, a unified theory for the Bragg geometry has been laid out to explain the different types of image formation from the scattering point of view. The means by which the photons “infiltrate” a real crystal have been studied. The theory suggests, for example, a mechanism for image contrast inversion in the Bragg geometry, and will also be found to be important in other topics of high current interest, such as x-ray standing wave surface analysis and x-ray inelastic scattering at the Bragg angle.
A Calculation of the Neutron (111,1̄1̄1/220) Three Beam Case
Authors: Treimer W.
Published: February 2015

After the development of a very common formalism for neutron three beam cases, a detailed investigation is given for the case (111, 1̄1̄1/220) and a comparisation with the (different) case (111, 1̄11/200) is presented. It is shown that the former case behaves different by concerning dispersion branches and reflection curves; both are asymmetric in respect to a wave incident in the exact Bragg direction and react more sensitive by upon small deviations of the incident wave from this direction. Simple formulae were found for the reflection curves of the intensities for all three beams behind a perfect crystal slab and the Pendellösung period.
An Ultra Small Angle Scattering Study of Hydrogen in Metals
Authors: Bader D. , Rauch H. , Zeilinger A.
Published: February 2015

A diffractometer using perfect crystals in symmetric Bragg arrangement, hence being useful for both neutron and X-ray radiation, has been built. The angular resolution of that instrument is better than 1 microradian, which corresponds to a scattering vector resolution of about 10-6 Å-1. This spectrometer was equipped with a laser light adjustment system which is sensitive to the relative angular position of the two perfect crystals. The spectrometer was used for the mea­surement of neutron scattering at very low angles of hydrated niobium and vanadium samples. The experimental results show an anomalously low attenuation of the neutrons when the metal-H sample is within the solubility a region. This property is explained by a lattice gas model of atomic H in the α-phase of the system. In the two phase region (α - β) a stronger attenuation of the neutron beam occurs due to the sample now being in an ordered interstitial solution phase.
Notizen: Comments on Sallhofers “Elementare Herleitung der Dirac-Gleichung”
Authors: Sexl Roman , Urbantke Helmuth
Published: February 2015

The transformation properties of the Dirac-equation derived by Sallhofer from electromagnetic principles are investigated.
Photoemission von Gd, Tb und den metallreichen Chloriden Gd2Cl3 und Tb2Cl3 / Photoemission of Gd, Tb and, the metal-rich chlorides Gd2Cl3 and Tb2Cl3
Authors: Ebbinghaus G. , Simon A. , Griffith A.
Published: February 2015

The photoelectron spectra (AlKα, Hell , Hei) of Gd, Tb, Gd2Cl3 and Tb2Cl3 are measured and discussed. They clearly indicate 4f7- and 4f8-configuration for the sesquihalides of Gd and Tb, respectively. In the case of Gd2Cl3 a band gap of approximately 1 eV is estimated.
First Experiences with Stark Effect Microwave Fourier Transform Spectroscopy
Authors: Bestmann G. , Dreizler H.
Published: February 2015

Measurements of the Stark effect by MWFT spectroscopy were not made up to now. We tested a modification of our spectrometer, which allows these measurements and opens this field also for MWFT spectroscopy.
Dislocations in Homoepitaxial Layers on "Dislocation Free" LEC-GaP Substrates
Authors: Umeno M. , Kawabe H. , Kokonoi T.
Published: February 2015

Dislocation structures in S-and N-doped homoepitaxial layers on GaP wafers are studied by high voltage electron microscopy. Many dislocations are introduced in the epilayer, even if the substrate is nearly dislocation free. The origins of the dislocations in this case are the microdefects, especially the perfect dislocation loops in the substrate. Dislocation dipoles are induced by dis-location half loops appearing at the epi-substrate interface and are classified into three types, two of which are concerned with the interactions of two dipoles in the epilayer, each interaction yielding a screw dislocation segment. The third type of dipole does not extend into the epilayer so far, but terminates and forms an elongated dislocation loop. The interactions and the terminations of dipoles decrease the density of the induced dislocations in proportion to the distances from the interface. The screw dislocations generated by the dipole interactions relax the torsional lattice distortion of the epilayer caused by dopant materials.
Experimental and Theoretical Studies on X-ray Plane Wave Images of a Dislocation in the Laue Case
Authors: Ishida H. , Miyamoto N. , Ishikawa T. , Kohra K.
Published: February 2015

Plane wave images of a dislocation in a silicon crystal were observed with (4̄04) diffraction of MoKα1 over a wide angular range. The fine structures consisting of five kinds of sub-images and their angular dependences were well simulated by the wave theory taking into account the finite angular spread and polarization states of the incident beam. The mechanism of the image formation is studied in terms of interbranch scattering, Eikonal theory and kinematical diffraction.
Experimentelle und semi-empirische Protonen-Hyperfein- kopplungen von 1.3-Benzodioxol-Radikal-Kationen und ihre Korrelation mit Reaktivitäten in elektrophilen Substitutionen
Authors: Fleischhauer Jörg , Ma Sun , Schleker Wolfgang , Gersonde Klaus , Twilfer Hans
Published: February 2015

The solution ESR X-band spectra of 1.3-benzodioxole (methylenedioxybenzene) (1), benzo- [1.2-d:4.5-d']bis[1.3]dioxole (2), benzo[1.2-d:3.4-d']bis[1.3]dioxole (3) and benzotris[1.3]dioxole (4) have been measured at room temperature. Hyperfine splitting constants of the aromatic ring protons of the compounds 1 - 3 have been determined. They have been correlated with the HOMO orbital densities of the adjacent carbon atoms and exhibit sufficient correspondence with the reactivities of these compounds in electrophilic substitution reactions. The splitting constants of all protons of the compounds 1 - 4 have been calculated by the INDO and HMO methods and have been compared with the experimental hyperfine values. By perturbation theory applied to the interactions between the π-MO'S of benzene and the dioxole fragment one can explain and understand the magnitudes of the experimental hyperfine splitting constants of the hydrogen atoms of these compounds. In particular, the hyperfine values of the methylene protons calculated by the HMO method are in good agreement with the experimental data.
Nuclear Magnetic Relaxation Induced by the Dynamics of Lattice Defects in Solids (7 = 3/2,I=2, and I= 5/2)
Authors: Becker K. D.
Published: February 2015

Results are presented for the relaxation of the nuclear magnetization via quadrupolar inter-actions caused by the dynamics of point-like lattice defects in cubic solids. For systems with nuclear spins I = 3/2, several aspects of the lineshape function of the absorption signal are con-sidered. The treatment includes the transition to the rigid lattice case, the presence of additional static quadrupolar interactions as well as the dynamic shift of the absorption, and saturation effects. For spins I = 2, expressions are given in detail for the parameters governing the relaxa-tion of the longitudinal and the transverse magnetization. For the I = 5/2 case, numerical results are presented for the same quantities accounting for complete and incomplete excitation of the spin system.
On the Decay of Symmetric Toroidal Dynamo Fields
Authors: Lortz Dietrich , Meyer-Spasche Rita
Published: February 2015

The “anti-dynamo” theorems for toroidal magnetic fields with axisymmetry and plane symmetry are generalized to the case of a compressible, time-dependent flow in a fluid with arbitrary conductivity
Electron Collisional Excitation of S XII
Authors: Saha H. P. , Trefftz E.
Published: February 2015

Atomic data have been obtained for the coronal ion S XII using the UCL program codes. Energy levels and radiative transition probabilities have been computed with different target descriptions allowing for configuration interaction and relativistic effects. Multi-configuration Hartree-Fock method is used to calculate the target wave functions. Collisional excitation cross sections between the 2 s2 2 p 2P0, 2s2p2 4P, 2D, 2S, 2P and the 2p3
4S0, 2D0, 2P0 eigenstates of S XII have been calculated using eight-state close coupling and distorted wave approximations with a target description employing a 3̄̄̄d̅ pseudo orbital. Collision strengths between the lowest five eigenstates of S XII have also been computed in five-state close coupling and distorted wave approximations for comparison. The results are compared with available theoretical work. It is found that the use of elaborate target wave functions and the choice of a more accurate scattering approximation may change the cross sections by more than 25% in some of the transitions
Numerische Simulation von Diffusionsprozessen mit nichtnegativitätserhaltenden konservativen Differenzenverfahren /
Authors: Gorenflo Rudolf , Kuban Angelika
Published: February 2015

After analyzing the general linear equation of diffusion (of a substance or of energy) with source term and given influx across the boundary we describe a method for constructing explicit and implicit conservative difference schemes which also preserve nonnegativity. We call a scheme “conservative” if via a convenient sum-analogue it does exactly imitate the conservation of a substance or energy. We concretize this method for the spatially two-dimensional heat equation in a rectangle with given influx. We also present a conservative implicit scheme with alternating directions
Leak Width of a Cusp-Confined Plasma
Authors: Knorr G. , Willis D.
Published: February 2015

The theoretical and numerical steady-state calculation of the width of an escaping plasma stream through a magnetic mirror solves the self-consistent potential and charge distribution for a low beta plasma. The leak width is obtained as the geometric mean of the ion and electron Lar-mor radius, also called hybrid width, in agreement with some experimental measurements. If the out-streaming plasma is unstable or collisional, the leak width can only larger, contrary to earlier results in the literature
Nonlinear Landau Damping of Alfvén Waves in a High β Plasma
Authors: Völk Heinrich J. , Cesarsky Catherine J.
Published: February 2015

A study is made of the nonlinear damping of parallel propagating Alfvén waves in a high β plasma. Two circularly polarized parallel propagating waves give rise to a beat wave, which in general contains both a longitudinal electric field component and a longitudinal gradient in the magnetic field strength. The wave damping is due to the interactions of thermal particles with these fields. If the amplitudes of the waves are low, a given wave (ω1, k1) is damped by the presence of all longer wavelength waves; thus, if the amplitudes of the waves in the wave spectrum increase with wave length, the effect of the longest waves is dominant.

However, when the amplitude of the waves is sufficiently high, the particles are trapped in the wave packets, and the damping rate may be considerably reduced. We calculate the induced electrostatic field, and examine the trapping of thermal particles in a pair of waves. Finally, we give examples of modified damping rates of a wave in the presence of a spectrum of waves, and show that, when the trapping is effective, the waves are mostly damped by their interactions with waves of comparable wavelengths
Monte Carlo Simulation of Neoclassical Transport in Axisymmetric and Ripple Tokamaks
Authors: Lötz W. , Nührenberg J.
Published: February 2015

Simple axisymmetric and ripple tokamak model fields are used to compute neoclassical trans-port coefficients by Monte Carlo simulation over a wide range of mean free paths in the approximation of small gyroradius. Further assumptions are a monoenergetic particle distribution which is only subject to pitch angle scattering and a vanishing electric field. Pfirsch-Schlüter, plateau, banana and ripple transport coefficients are obtained. In the ripple regime the description is unified by introducing the concept of an effective ripple. Cases in which ripple transport is diminished due to collisionless detrapping are observed
Collective Ion Acceleration by Relativistic Electron Rings in the Magnetosphere
Authors: Schumacher U. , Boswell R. W.
Published: February 2015

Calculations are presented which show that the collective acceleration of ions by rings of relativistic electrons seems feasible in the polar regions of a dipolar magnetospheric field. The well known magnetic field of the earth is taken as an example and it is found that with rings of electrons of only 4 MeV initial energy, deuterons can be accelerated up to energies of about 50 MeV from rest in a distance of one third of an earth radius. Although the drift motion of the electron rings across the magnetic field lines is negligible for latitudes greater than 45°, in the equatorial plane the ring drifts at constant altitude with a speed proportional to the local magnetic field index
Two Photon Ionization of Benzene in Methanol and Cyclohexane Solution
Authors: Tagawa S. , Beck G. , Schnabel W.
Published: February 2015

Irradiation of benzene with 15 ns flashes of 265 nm light caused ionization as evidenced by optical absorption measurements. In the case of dilute methanol solutions solvated electrons were formed. The yield depends on the intensity of the incident light I as ϕ (es̄olv) ∝ I1.8. In the case of cyclohexane solution dimer radical cations were detected by their absorption between 600 and 1100 nm. O2 enhances the yield of dimer cations because it scavenges electrons, thus impeding ion recombination.
Dielectric Behaviour of Ice Microcrystals Dispersed within Suspensions: A DTC Study
Authors: Pissis P. , Apekis L. , Christodoulides C. , Boudouris G.
Published: February 2015

The dielectric properties of water-in-oil (W/O) suspensions have been studied by means of the depolarization thermocurrent (DTC) method in the temperature range of 85-250 K. Two predominant peaks have been observed at about 140 and 225 K. Evidence has been obtained that the peak at 140 K and the dielectric absorption observed by many investigators at sub-zero temperatures in the kHz frequency range are due to the same relaxation mechanism.
Eisenionen als Spinsonden in CdGa2S4-Kristallen / Fe(III) Ions as Spin Probes in CdGa2S4 Crystals
Authors: Frick B. , Siebert D.
Published: February 2015

In EPR studies on Fe(III) ions in CdGa2S4 crystals, in accordance with the two different Ga sites two paramagnetic centers could be detected which differ widely in their axial parameter D. An investigation of the crystal field allowed a unique site assignment. A comparison with the Fe(III) resonances in CuGaS2 and AgGaS2 does show that the superposition model of Newman and Urban cannot be applied to CdGa2S4 with similar parameters as in the chalcopyrite structures. - A characteristic twinning could be revealed, similar to the “reversed cubic structure” in sphalerite.
Nuclear Magnetic Resonance of Amorphous Alloys CuxZr100-x(40≦x≦60)
Authors: Abart J. , Socher W. , Voitländer J.
Published: February 2015

91Zr-and 63Cu-NMR measurements of the amorphous alloys CuxZr100-x(40≦x≦60) are reported. By comparison of the experimental quadrupole disturbed spectra with simulated spectra of the amorphous alloys a short range order can be deduced, which is similar to the local lattice symmetry of the corresponding crystalline compounds. Furthermore the Knight shift of both nuclei in the alloys could be determined.
Determination of a High Potential Barrier Hindering Internal Rotation from the Ground State Spectrum The Methylbarrier of cis-Propanal
Authors: Hardy J. A. , Cox A. P. , Fliege E. , Dreizler H.
Published: February 2015

The barrier hindering internal rotation of the methyl group was determined by analysing the splittings of rotational lines in the ground state. So model errors are minimized. The assignment was checked by double resonances and a centrifugal distortion analysis.
Molecular Dynamics Simulation of an Aqueous MgCl2 Solution. Structural Results
Authors: Dietz W. , Riede W. O. , Heinzinger K.
Published: February 2015

A molecular dynamics simulation of a 1.1 molal aqueous MgCl2 solution has been performed employing the central force model for water. The effective pair potentials for ion-water have been derived from ab initio calculations. The basic box with a sidelength of 18.30 Å contained 200 water molecules, 8 anions and 4 cations, corresponding to an experimental density of 1.079 g/cm3 . The simulation extended over about 3.3 picoseconds at an average temperature of 309 K. The structure of the solution is described by radial distribution functions and the orientation of the water molecules in respect to physically meaningful directions. Values for the dielectric constant and hydration energies have been calculated. The strong influences of the twofold charged magnesium ion on the geometry of the water molecules and the structure of the hydration shell is discussed in comparison with the results of a previous simulation of a 2.2 molal NaCl solution.
Magnetic Susceptibility of Pressed Powders of Some Rare-Earth Iron Garnets
Authors: Yadava V. R. , Verma B. K. , Tripathi A. K. , Lai H. B.
Published: February 2015

The molar magnetic susceptibilities (χм) of spherical balls of rare-earth iron garnets REIG's, with RE = Y, Gd, Dy, Ho, Er and Yb, prepared from pellets pressed at pressures ranging from 2 to 8 × 107 kg m-2 , have been measured in the temperature range 300-900 K. It is found that χмα exp( - f), where f is the pore fraction of the pressed balls. It has also been observed that χм for a particular garnet at a fixed temperature increases from powder through pressed material to single crystal. REIG's reveal typical ferrimagnetic behaviour with the ferrimagnetic Curie temperature (Tc) lying in the range 550-570 K for single crystals. In general, for pressed material Tc increases linearly with density. The χм
-1 vs, T variation has been analysed using molecular field theory. It has been found that for T ≫ Tc the magnetic ions behave as if they were almost free and yield a magneton number very close to their free ion value.
Effect of Temperature on the Mechanoluminescence of Coumarin Crystals
Authors: Chandra B. P. , Deshmukh N. G.
Published: February 2015

The mechanoluminescence of coumarin crystals is studied. It is found that mechanoluminescence decreases sharply with temperature near the melting point and that it may be a useful probe for studying the behaviour of crystals near the melting points.
EPR of Cu2+ in Ferroelectric LiH3(SeO2)2 Single Crystals
Authors: Waseem Mohd. , Dayal R. , Jain Vimal Kumar
Published: February 2015

The electron paramagnetic resonance of Cu2+ in ferroelectric LiH3(SeO3)2 has been studied at 298 K in X-band. The Cu2+ appears to substitute Li+ in the lattice with the z-axis nearly along the Li-O(6) bond direction. The spectra have been analysed using the spin-Hamiltonian appropriate for Cu2+ in orthorhombic symmetry.
Influence of O2 on the 535.0 nm Thallium Line
Authors: Lisicki E. , Bielski A. , Szudy J.
Published: February 2015

The effect of molecular oxygen on the broadening and shift of the 535.0 nm Tl line resulting from the photodissociation of thallium iodide vapour was studied at low densities of O2. The broadening and shift coefficients were determined.
Pressure Dependence of the Nematic State Temperature of a Compensated Cholesteric Liquid Crystal
Authors: Pollmann P. , Wiege B.
Published: February 2015

At a certain temperature Tn (nematic temperature) a mixture of two cholesteric components which separately form helices of opposite senses behaves like a nematic. An inversion of the helical structure occurs when passing Tn, from a right-handed to a left-handed structure or vice versa. In the temperature-pressure space such compensated mixtures therefore will exhibit an inversion line which - on the basis of optical rotatory power measurements under high pressure - is presented for the first time.
The Electronic Structure of Closed Shell Metallocenes in the Ground State and in the Cationic Hole-States
Authors: Böhm Michael C.
Published: February 2015

The electronic structure of tne closed shell metallocenes bis(π-cyclopentadienyl)magnesium (1), bisbenzene chromium (2), ferrocene (3) and cyclopentadienyl benzene manganese (4) has been studied in the ground state as well as in the low-lying cationic states. The computational framework is a semiempirical INDO Hamiltonian, the theoretical framework for the investigation of the cationic hole-states is the Green's function method. The calculated ionization energies are compared with the photoelectron (PE) spectra of the four closed shell metallocenes. The interrelation between theoretically determined reorganization energies and the localization properties of the orbital wave functions or the nature of the transition metal center is analyzed. General rules concerning the validity of Koopman's theorem in transition metal complexes are formulated.
Ab Initio Calculation of Molecular Properties of Cyanopolyynes, H—(C≡C)n—CN
Authors: Ha Tae-Kyu , Nguyen Minh Tho
Published: February 2015

Results of ab initio SCF calculations on cyanopolyynes, H-(C ≡ C)n-CN with n up to 7 are reported. Calculated rotational constants and one-electron properties are compared with the available experimental values. The effects of the C ≡ C chain length on the physical properties are discussed.
Notizen: WKBJ Calculation of the Energy Levels of an Anquartic Potential
Authors: Kesarwani R. N. , Varshni Y. P.
Published: February 2015

A new anquartic potential is proposed. The pattern of its eigenvalues is calculated by using the four-term WKBJ approximation. The results are shown graphically and are compared with those found for another anquartic potential studied in a previous paper.
On Electro- and Thermomigration and Thermoelectric Transport Coefficients in Metals
Authors: Bohn H.-J. , Simon G.
Published: February 2015

The system of coupled Boltzmann transport equations for electrons, phonons and impurities in metals is set up and solved with special interest for the effect of the cross-coupling terms. General expressions for the effective charge in electromigration and heat of transport in thermomigration are given. The cross-coupling terms in the transport equations lead to a number of corrections in the thermoelectric transport coefficients. Noteworthy is the result that the resistance by impurities depends now on the temperature. The investigation is restricted to high temperatures, isotropic dependence of the energies of electrons and phonons on wave number vector, and to normal scattering processes of phonons.
Electronic Structure of Solvent-Polarity Indicators. Solvatochromism and Tautomeric Epuilibria of Styryl-Merocyanines
Authors: Abd-El-Mottaleb M. S. A.
Published: February 2015

Solvatochromic and halochromic behaviour of two unsymmetrical merocyanine-type dyes, namely 2-[2′- and 4′-hydroxystyryl]-pyridinium methiodide, are studied.

In alcoholic and hydrogen-bond-acceptor (HBA) solvents their visible absorption spectra exhibit an additional long-wavelength band suggesting the existence of tautomeric equilibria in their solutions. The tautomeric equilibrium constants in triethanolamine-acetone mixed solvents are determined.

Quantum mechanical MO method PPP-π-SCF-CI is used to calculate the electronic spectra and the underlying keto-enol-tautomeric stability. Deprotonation of the OH group is shown to provide destabilization in binding energy in excess of 5 eV in agreement with the experimental results indicating that these indicators exist mainly as protonated species (enol form) in their solutions.

Furthermore, solvent-induced changes in the ground-state electronic structures are examined by means of 1H-NMR spectroscopy and the PPP calculations.
Microwave and Millimeterwave Spectrum of Bromofluoroacetylene (Br—C≡C—F)
Authors: Andolfatto M. , Kleibömer B. , Guarnieri A.
Published: February 2015

The microwave and millimeterwave spectra of Bromofluoroacetylene 79Br-C ≡ C-F and 81Br-C ≡ C-F in natural abundance have been investigated. The molecule has been found to be linear. The rotational constant, the centrifugal distortion constants Do, the Bromine quadrupole coupling constant and the electrical dipole moment have been determined.

Some r0-structures have been calculated assuming different values for the C ≡ C distance.
Uniformly Constructing a Series of Nonlinear Wave and Coefficient Functions’ Soliton Solutions and Double Periodic Solutions for the (2 + 1)-Dimensional Broer-Kaup-Kupershmidt Equation
Authors: Chen Yong , Wang Qi , Lang Yanghuai
Published: February 2015

By using a new more general ansatz with the aid of symbolic computation, we extended the unified algebraic method proposed by Fan [Computer Phys. Commun. 153, 17 (2003)] and the improved extended tanh method by Yomba [Chaos, Solitons and Fractals 20, 1135 (2004)] to uniformly construct a series of soliton-like solutions and double-like periodic solutions for nonlinear partial differential equations. The efficiency of the method is demonstrated on the (2+1)-dimensional Broer-Kaup- Kupershmidt equation.
Exact Traveling Wave Solutions for the Modified Kawahara Equation
Authors: Elgarayhi Ahmed
Published: February 2015

The mapping method is used with the aid of the symbolic computation system Mathematica for constructing exact solutions of the modified Kawahara equation. By this method the modified Kawahara equation is investigated and new exact traveling wave solutions are obtained. The solutions obtained in this paper include Jacobi elliptic solutions, combined Jacobi elliptic solutions, solitary wave solutions, periodic wave solutions, trigonometric solutions and rational solutions.
Partitioning of π-Electrons in Rings of Fibonacenes
Authors: Gutman Ivan , Balaban Alexandru T. , Randić Milan , Kiss-Tóth Christian
Published: February 2015

The partitioning of π-electrons into rings of benzenoid hydrocarbons is examined in the case of fibonacenes. It is demonstrated that the π-electron contents (ECs) of the hexagons of fibonacenes satisfy the following peculiar regularities: Let h be the number of hexagons, and EC(i) the electron content of the i-th hexagon. Then EC(i) is maximal for i = 1 and i = h, and minimal for i = 2 and i = h−1 . Going from the end towards the center of the fibonacene chain, EC(1) >EC(3)> EC(5)> · · · and EC(2)< EC(4) <EC(6) <· · · and EC(1)> EC(2)< EC(3) >EC(4) EC(6) <· · · . For large values of h, the asymptotic values of EC(1) and EC(2) are 5.146 and 3.798, whereas of the central ring(s) 4 π-electrons.
The D2h Distortion around the Cu2+ Center in Cu0.5Zr2(PO4)3 Single Crystals
Authors: Du Y. Huang, M. L. , Ni C. , Wen J. F.
Published: February 2015

A formula for the calculation of the three g factors of 3d9 ions in an orthorhombic field D2h has been derived. Using it to investigate the EPR g factors of the Cu2+ ions in single crystals of Cu0.5Zr2(PO4)3, the variation of the g factors on changing the angle α between the x- and y-axis has been explained. According to that, it can be confirmed that the angle α of the D2h distortion is about 62.6°. PACS: 71.70C; 76.30F
Exact Jacobian Elliptic Function Solutions To The Double Sine-Gordon Equation
Authors: Fu Zuntao , Liu Shikuo , Liu Shida
Published: February 2015

In this paper, two transformations are introduced to solve the double sine-Gordon equation by using knowledge of the elliptic equation and Jacobian elliptic functions. It is shown that different transformations can be applied to obtain more kinds of solutions to the double sine-Gordon equation. PACS: 03.65.Ge
Painlevé Properties And Exact Solutions Of The Generalized Coupled Kdv Equations
Authors: Ye Li-Jun , Lin Ji
Published: February 2015

The generalized coupled Korteweg-de Vries (GCKdV) equations as one case of the four-reduction of the Kadomtsev-Petviashvili (KP) hierarchy are studied in details. The Painlevé properties of the model are proved by using the standard Weiss-Tabor-Carnevale (WTC) method, invariant, and perturbative Painlev´e approaches. The meaning of the negative index k = −2 is shown, which is indistinguishable from the index k = −1. Using the standard and nonstandard Painlevé truncation methods and the Jacobi elliptic function expansion approach, some types of new exact solutions are obtained.
The Generation Of Lump Solitons By A Bottom Topography In A Surface-Tension Dominated Flow
Authors: Lu Zhiming , Liu Yulu
Published: February 2015

The generation of lump solitons by a three-dimensional bottom topography is numerically investigated by use of a forced Kadomtsev-Petviashvili-I (KP-I) equation. The numerical method is based on the third order Runge-Kutta method and the Crank-Nicolson scheme. The main result is the pairwise periodic generation of two pairs of lump-type solitons downstream of the obstacle. The pair with the smaller amplitude is generated with a longer period and moves in a larger angle with respect to the positive x-axis than the one with the larger amplitude. Furthermore, the effects of the detuning parameter on the generation and evolution of lumps are studied. Finally the waves propagating upstream of the obstacle are also briefly investigated.
Multiobjective Optimization Of An Extremal Evolution Model
Authors: Elettreby Mohamed Fathey
Published: February 2015

We propose a two-dimensional model for a co-evolving ecosystem that generalizes the extremal coupled map lattice model. The model takes into account the concept of multiobjective optimization. We find that the system is self-organized into a critical state. The distribution of avalanche sizes follows a power law.
Vibrational Properties of Tellurium Tetrachloride
Authors: Baran Enrique J.
Published: February 2015

On the basis of the most recently reported spectroscopic data on vibrational modes in TeCl4 and structural parameters of TeCl4, an estimation of its main force constants complemented with the calculation of mean amplitudes of vibration in a wide temperature range have been performed. Also thermodynamic functions for the ideal gaseous state of the molecule calculated, using the statistical mechanics approach.
Physical Properties of a New Type of Molten Electrolytes, FeCl3-DMSO2
Authors: Yang Chao-Chen , Shu Min-Fong
Published: February 2015

Some physical properties of ferric chloride-dimethyl sulfone (FeCl3-DMSO2) melts were investigated. The phase diagram was determined by differential scanning calorimeter and thermogravimetric analyzer. The electric conductivity, measured with computerized direct-current method, increased with increasing temperature and DMSO2 content. The conductivity was maximal (0.02149 S/cm) at 115 °C for 30 mol% FeCl3. The densities of all melts decreased with increasing temperature and DMSO2 content. The equivalent conductivities were given by Λ = κMmix/ρ, where Mmix is the mean equivalent weight of the binary melts. These equivalent conductivities were fitted by the equationΛ =Λoexp(−EΛ /RT), where the activation energies EΛ were 8.63, 22.94, 25.92 kJ/mol for 30, 40, 50 mol% FeCl3, respectively.
Dopant Concentration Effect on NiO-Doped Sodium Metaphosphate Glasses: A Combined X-Ray Absorption Fine Structure (XAFS) and UV/VIS/NIR Spectroscopic Investigation
Authors: Brendebach Boris , Glaum Robert , Funke Michael , Reinauer Felix , Hormes Josef , Modrow Hartwig
Published: February 2015

NiO-doped sodium metaphosphate glasses (NaPO3)1−χ(NiO)χ (0.008 ≤ χ ≤ 0.30) show a color shift from yellow to orange-brown with increasing NiO concentration. XANES and EXAFS spectra of these glasses suggest the presence of [NiIIO6] groups as chromophores. EXAFS (Ni K-edge) analysis of the NiO-doped phosphate glasses including an evaluation of higher coordination shells leads to dav(Ni-O) = 2.06(2) Å. Evidence is provided for an increased connectivity of [NiIIO6] chromophores at higher NiO concentration in the glasses. A decrease in the intensity of the main absorption edge with increasing nickel oxide concentration is observed. This systematic decrease is attributed to a change in the bonding characteristics between nickel(II) and the coordinating phosphate groups from mainly ionic to a small but significant contribution of covalent bonding. A similar effect is observed in the electronic absorption spectra of glasses showing a decrease of the Racah parameter B for the Ni2+ ions.
Magnetic Field Effects On Surface Ion Plasma Wave In Semi-Bounded Magnetized Dusty Plasmas
Authors: Lee Myoung-Jae , Jung Young-Dae
Published: February 2015

The effects of magnetic field strength on low-frequency surface ion plasma wave are investigated in semi-bounded magnetized dusty plasmas. The dispersion relation of the surface ion plasma wave is obtained by the plasma dielectric function with the specular reflection boundary condition. The results show that a transition from linear increase into the final level, i. e., the occurrence of a wave resonance. At a given frequency the phase velocity stays almost constant as long as the frequency remains below the respective resonance frequency.
Exact Complexiton Solutions of the (2+1)-Dimensional Burgers Equation
Authors: Chen Yong , Wang Qi
Published: February 2015

Based on two different Riccati equations with different parameters, many new types of complexiton solutions to the (2+1)-dimensional Burgers equation are investigated. Such complexiton solutions obtained possess various combinations of trigonometric periodic and hyperbolic function solutions, various combinations of trigonometric periodic and rational function solutions, various combinations of hyperbolic and rational function solutions. - PACS numbers: 02.30.Ik, 05.45.Yv
New Types of Interactions between Solitons of the (2+1)-Dimensional Broer-Kaup-Kupershmidt Equation
Authors: Dai Chao-Qing , Meng Jian-Ping , Zhang Jie-Fang
Published: February 2015

By means of the extended homogeneous balance method and the variable separation approach, more general variable separation solutions of the (2+1)-dimensional Broer-Kaup-Kupershmidt equation are obtained. Based on the variable separation solution and by selecting appropriate functions, new types of interactions between the multi-valued and the single-valued solitons, such as compactonlike semi-foldon and compacton, peakon-like semi-foldon and peakon, and bell-like semi-foldon and dromion, are investigated. Meanwhile, we also discuss the phase shift of these interactions. - PACS: 02.30.Jr, 02.30.Ik
Dynamics of Paired Bright Solitons Induced by the Modulational Instability of Two-component Bose-Einstein Condensates
Authors: Hong Woo-Pyo
Published: February 2015

We investigate numerically the dynamics of paired bright solitons induced by the modulational instability of two-component Bose-Einstein condensates. We derive the analytic gain spectrum by the modulational instability in terms of the interspecies and intraspecies scattering constants and classify the region where the instability occurs. The constraints on the interspecies and intraspecies scattering constants for the existence of the paired bright solitons are found. Using numerical simulations, it is shown that the paired bright solitons induced by the modulational instability exhibit complicated dynamical behaviors depending on the sign and strength of the interspecies and intraspecies scattering constants. - PACS numbers: 03.75.Fi, 05.30.Jp, 32.80Pj, 67.90.+z
Phase Transitions and Pre-transitional Effects in N-(p-n-Pentylbenzylidene)-p-n-pentylaniline (5.5) and its Oxygen Derivatives – A Dilatometric Study
Authors: Ajeetha N. , Rao M. Ramakrishna Nanchara , Prasad P.V. Datta , Pisipati Venkata G. K. M.
Published: February 2015

The density of N-(p-n-pentylbenzylidene)-p-n-pentylaniline (5.5) and its two oxygen derivatives, viz. N-(p-n-pentylbenzylidene)-p-n-pentyloxyaniline (5.O5) and N-(p-n-pentyloxybenzylidene)-p-npentyloxyaniline (5O.O5), is reported for the isotropic (I), nematic (N), smectic-G (SG) and crystalline (K) phases. Dilatometric results reveal the first order nature of the I-N, N-SG and N-K transitions. A rare occurrence of the N-K transition is found for the compound 5O.O5 at a considerably higher temperature. From the observed density data pre-transitional effects are estimated for the isotropic to the first mesomorphic phase. The results are discussed in the light of data reported on other Schiff base benzylidene anilines
Indium Triiodide Complexes of Bis(diphenyIphosphino)ethane (dppe) and its Disulfide (dppeS2)
Authors: Sigl Marcus , Schier Annette , Schmidbaur Hubert
Published: February 2015

Bis(diphenylphosphino)ethane (dppe) and its disulfide (dppeS2) react with two equivalents of indium triiodide to give high yields of the corresponding 1:2 adducts. According to crystal structure determinations, both compounds are molecular bis-terminal complexes with the ligands in an all-trans conformation. Contrary to previous findings for complexes of the indium trihalides and of GaBr3 and Gal3 with ditertiary phosphines in fixed cis-structure [bis(diphenylphosphino)ethene or -benzene], no iodide redistribution is observed to give the ionic species [(dppe)Inl2]+ [InI4 ]- . The molecular structures are also retained in solution.
1,3-Distanna-2-phospha-[3]ferrocenophanes - Synthesis, Reactivity and NMR Spectroscopic Properties
Authors: Herberhold Max , Steffl Udo , Wrackmeyer Bernd
Published: February 2015

1,1,3,3-Tetramethyl-2-organo(R)-1,3-distanna-2-phospha-[3]ferrocenophanes [R = Me (2a), tBu (2b), C6H11 (2c), Ph (2d)] and one arsa-analogue 2d(As) were obtained from the reaction of 1,1′-bis(chlorodimethylstannyl)ferrocene 1 with either bis(trimethylsilyl)methylphosphane or the dilithio derivatives, Li2PR and Li2AsPh, respectively. All compounds 2 react with chalcogens (oxygen, sulfur, selenium) by cleavage of the Sn-P bonds and formation of the known 1,3-distanna-2-chalcogena-[3]ferrocenophanes. In contrast, 2d traps pentacarbonylmetal fragments [M(CO)5] to give the stable phosphane complexes [M = Cr (4d), Mo (5d), W (6d)]. The 1,1′-bis(diorganophosphanostannyl)ferrocenes [R = tBu (3b), Ph (3d)] were prepared for comparison of NMR data. The ferrocenophanes 2 are fluxional with respect to fast movement of the cyclopentadienyl rings which induces inversion at the pyramidal phosphorus atom. This dynamic process is slow in the cases of 2d(As) and of the pentacarbonyl complexes 4d - 6d. All new compounds were characterised by 1H, 13C, 31P and 119Sn NMR spectroscopy. Various 2D heteronuclear shift correlations (e.g. 31P/1H and 119Sn/1H ) were carried out for the compounds 2 and also for non-cyclic derivatives such as bis(trimethylstannyl)phenvlphosphane and -arsane in order to determine absolute signs of coupling constants [e.g. 1J(119Sn,31P) > 0 and 2J(119Sn,117Sn) < 0]. The NMR data suggest that the molecular frameworks of the ferrocenophanes 2 are not particularly strained.
Oxidative S-S-Kopplung von 1,2-Dithiooxalat durch intramolekulare Redoxreaktion der Selen(II)- und Tellur(II)-Komplexe/Oxidative S-S Coupling of 1,2-Dithiooxalate by Intramolecular Redox Reaction of the Selenium (II) and Tellurium(II) Complexes
Authors: Drutkowski U. , Strauch P.
Published: February 2015

The reaction of sodium monochalcogenopentathionates, Na2[Y(S2O3)2] (Y = Se, Te) with potassiumdithiooxalate in a water/methanol solution in presence of large cations (e. g. Ph4P+, Ph4As+ or BzlPh3P+) yields complexes of the type [Y(dto)2]2- (Y = Se, Te). These complexes are of limited stability and undergo a redox reaction in solution. As the main product of this redox process the 3,4-dithiahexane-2,5-dione-1,6-di(thiocarboxylate) was isolated and characterized by X-ray structure analysis as the benzyltriphenylphosphonium salt (monoclinic space group P2J/c, Z = 2, a = 8.899(5) Å, b = 16.458(2) Å, c = 16.034(6) Å and β = 98.02(2)°). With Te2+ (Y = Te) as the coordination center we have been able to isolate the intermediate complex (Ph4P)2[Te(dto)2].
Darstellung enantiomerenreiner 3-Oxa-2,7-diazabicyclo[3.3.0]octane und ihre Umwandlung in andere bicyclische Ringsysteme/Preparation of Pure Enantiomeric 3-Oxa-2,7-diazabicyclo[3.3.0]octanes and their Conversion to Other Bicyclic Ring-Systems
Authors: Aurich Hans Günter , Soeberdt Michael
Published: February 2015

Pure Enantiomeric (S)-N-benzylalaninol (R1 = Me) and (S)-N-benzylvalinol (R1 = i-Pr) were allylated with Br-CH2-CH=CR2R3 (R2 = R3 = H; R2 = Ph, R3 = H; R2 = R3 = Ph). Swern oxidation followed by treatment with methylhydroxylamine afforded nitrones 6 (Me- N(O)=CH-CHR1-N(CH2Ph)CH2-CH=CR2R3) which underwent an intramolecular 1,3-dipolar cycloaddition providing 3-oxa-2,7-diazabicyclo[3.3.0]octanes, e.g. (1R,5R,8S)-7-benzyl-2,8- dimethyl-3-oxa-2,7-diazabicyclo[3.3.0]octane 7a (R1 = Me, R2 = R3 = H) and (1R,4R,5R,8S)- 7-benzyl-2,8-dimethyl-4-phenyl-3-oxa-2,7-diazabicyclo[3.3.0]-octane 7b (R1 = Me, R2 = Ph, R3 = H).

Reductive ring opening of 7a and 7b afforded the corresponding a-hydroxyalkylated pyrrolidines (9a: R2 = H or 9b: R2 = Ph. resp.). Condensation of these compounds with benzaldehyde yielded a mixture of diastereomeric 4-oxa-2,8-diazabicyclo[4.3.0]- nonanes: 10a/11a (1R,3S,6R,9S)/(1R,3R,6R,9S) R1 = Me, R2 = R3 = H and 10b /lib (1R,3S,5R,6R,9S)/(1R,3R,5R,6R,9S) R1 = Me, R2 = Ph, R3 = H. Pyrrolidine 9b was converted to the mesylate which formed (1R,4S,5R,7S)-3-benzyl-4,6-dimethyl-7-phenyl-3,6-diazabicyclo[3.2.0]heptane 13 along with (4R,5S)-1-benzyl-3,5-dimethyl-4-styryl-imidazolidine 15 upon treatment with sodium hydroxide.
Synthesen und Kristallstrukturen von Tris(di-n-propylamino)-p-brombenzylphosphonium-bromiden: [(C3H7)2N]3PCH2C6H4Br+Br- und [(C3H7)2N]3PCH2C6H4Br+Br3
-/Syntheses and Crystal Structures of Tris(di-n-propylamino)-p-bromobenzyl-phosphonium Bromides: [(C3H7)2N]3PCH2C6H4Br+Br- and [(C3H7)2N]3PCH2C6H4Br+Br3
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Authors: Nolte J. , Neubauer P. , Vogt H. , Meisel M.
Published: February 2015

Tris(di-n-propylamino)-p-bromobenzylphosphonium bromide [(C3H7)2N]3PCH2C6H4Br+- Br- (1) has been prepared by the reaction of tris(di-n-propylamino)phosphine with p-bromobenzylbromide in methylene chloride. The colorless crystals are monoclinic, space group P21, Z = 2, a = 930.2(3), b = 1501.2(3), c = 1093.5(2) pm, β = 105,97(4)°. The lattice contains Br- anions and [(C3H7)2N]3PCH2C6H4Br+ cations. [(C3H7)2N]3PCH2C6H4Br+Br- (2) has been obtained by treating 1 with equimolar quantities of elemental bromine in methylene chloride solution. The yellow-red crystals of 2 are triclinic, space group P1̄, Z = 2, a = 1069.5(3), b = 1267.7(7), c = 1273.7(3) pm, α= 87.27(3), β = 82,67, γ = 67.15°, and consist of [(C3H7)2N]3PCH2C6H4Br+ cations and linear Br3
- anions. The three N atoms in the cations of 2 are planar.