bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Particle Densities and Line Profiles in Plasmas by Resonance Interferometry: A Feasibility Study using Computer Simulated Refractivity Data
Authors: Haas C. , Pretzier G. , Jäger H. 
Published: February 2015

Abstract
The principles of resonance interferometry are described with regard to two applications: High accuracy particle density determination within plasmas and interferometrical determination of spectral line profiles. The usability of this technique is investigated numerically, and physical limits are given for the regions in which resonance interferometry may be employed successfully. The discussion and the results are helt general for making it possible to decide whether or not to apply this method for an actual problem. An example (an object being longitudinally homogeneous with respect to the direction of light: end-on observation) shows how to use the presented results for calculating the detection limits of the method for a given object geometry.
Dynamic Modelling of Heart Beat
Authors: Grossmann Siegfried , Ranft Sabine 
Published: February 2015

Abstract
Two recently introduced methods to analyze heart beat are checked by applying them to numerically produced time series representing artificial heart beat. The phase space diagram method (G. E. Morfill, G. Schmidt) depends on the variability of the sinus rhythm and the coupling interval of the extrasystoles. The risk index method (J. Kurths et al.) seems to measure different aspects of heart beat.
Can Twisted Internal Charge-Transfer(TICT)State be Formed in Rigid Polymers?
Authors: Kawski A. , Piszczek G. , Kukliński B. 
Published: February 2015

Abstract
Absorption, emission and emission anisotropy spectra of 4-cyano-N,N-dimethylaniline (CDMA) and 4-cyano-2,6,N,N-tetramethylaniline (CTMA) were investigated in polyvinyl alcohol) (PVA) films. It was found that the CDMA and CTMA molecules in PVA films at room temperature display phosphorescence, the emission band of which overlaps with the longwave fluorescence band a. The low value of the emission anisotropy shows that in the rigid PVA matrix there are microscopic defects in the form of empty spaces in which a certain fraction of the CDMA or CTMA molecules can attain twisted intramolecular charge-transfer states (TICT) due to rotational relaxation. The emission anisotropies in the shortwave, b, and longwave, a, fluorescence bands of CDMA in propylene glycol were found to be distinctly different, this indicating that the directions of the transition moments are not parallel.
EPR of VO2+Doped Cd2ZrF8• 6H2O SingleCrystals
Authors: Jayaram Geetha , Krishnan V. G. 
Published: February 2015

Abstract
X-band EPR measurements have been carried out on VO2+ doped single crystals of Cd,ZrF8 • 6H20. The angular variation of the 19F superhyperfine structure did show that the VO2+ ion occupies an interstitial site with C4v symmetry.
Off-Resonance Nutation NQR Spectroscopy of Powders
Authors: Sinjavsky N.Ja. 
Published: February 2015

Abstract
The peculiarities of nutation NQR spectra of nuclei with spin I=3/2 in powders are considered in the case of a resonance offset. An equation, which takes into account the offset is given for the determination of the asymmetry η. It is shown that structural of monocrystals by means of nutation spectroscopy are possible.
Phase Diagrams of Binary Systems of Non-Mesogenic Components:Caesium-Sodium and Caesium—Lithium Iso-Butyrates
Authors: Mirnaya T. A. , Yaremchuck G. G. , Volkov S. V. 
Published: February 2015

Abstract
The phase diagrams of the binary systems given in the title have been studied by differential thermal analyses and hot stage polarization microscopy. Smectic liquid crystals are found in some composition ranges of the binary with sodium iso-butyrate. The liquid crystal appearance in this system is explained by latent mesomorphism of both components and by the additional electrostatic stabilization of the ionic mesophase because of dissimilar cation interactions. The unlike conditions for the exhibition of latent mesomorphism of caesium isobutyrate in the two systems is discussed.
Notiz: Decelerated β-Decay of Tritium Solved in Titanium
Authors: Reifenschweiler Otto 
Published: February 2015

Abstract
It is shown that it is not possible to explain the measured decrease of tritium radioactivity by a change between ad­ sorption at the surface and bulk absorption in small titanium particles as argued in a recent note in this periodical. As to the reduction of titanium oxide by tritium, it is pointed out that the enthalpy of formation of titanium oxide is nearly 4 times that of water.
On the Analysis of Twisted Director Configurations
Authors: Kilian A. , Sonnet A. 
Published: February 2015

Abstract
A twist tensor (T-tensor) is introduced, which is defined for differentiable vector and director fields. Its eigensystem describes the local helical structure of the underlying field. It can have up to two nonzero eigenvalues, which indicate whether the local structure is untwisted, helical or double-twisted. The eigenvalues q
i, if real valued, are the helical wave numbers, and the corresponding eigenvectors represent the local twist axes. The T-tensor can serve as a tool to analyze director configurations in chiral nematic liquid crystals, and applications in computational fluid dynamics seem feasible.
Algebraic Approach to the Fixed Point Structure of the Quantum Mechanical Dirac -Coulomb System
Authors: Nag Nivedita , Roychoudhury Rajkumar 
Published: February 2015

Abstract
It is shown that a non-perturbative ß like function can be obtained for a Dirac-Coulomb system with both vector and scalar couplings using the properties of 0(2,1) algebra and the tilting operator mechanism.
High Voltage Plane Cathode -Comb Anode Discharge
Authors: Mezei P. 
Published: February 2015

Abstract
Investigations on the characteristics of a plane cathode-comb anode discharge are presented. This discharge arrangement consists of a plane cathode with a series of anodes, resembling a comb, above it. A significant increase of the discharge voltage was obtained by increasing the number of comb-teeth. Voltage-current characteristics, the intensity and the spatial distribution of He, Al, and Ar spectral lines were investigated as functions of the number of comb-teeth, He pressure and discharge current. Due to the increase of discharge voltage, the spectral line intensities increased significantly in the negative glow region. In case of the Al-I 396.1 nm and the He-I 318.7 nm lines an intensity peak was observed also in the cathode glow region. This peak was pronounced in the case of high voltage anode arrangements and is attributed to excitation by positive ions.
Friction Drag on a Cylinder Moving in a Nematic Liquid Crystal
Authors: Ruhwandl R. W. , Terentjev E. M. 
Published: February 2015

Abstract
The flow of a liquid crystal around a body depends not only on the geometry of the body but also on the director field around it. For low-Ericksen number flows, the director distribution largely remains in its static equilibrium texture (along a uniform direction far away from the body and, for instance, perpendicular to its surface). We calculate the velocity and pressure of a cylinder in a nematic flow numerically, taking into account topological defects on the particle surface and find the drag force acting on the moving body. The drag force is, in general, non-central, i.e. not aligned with the direction of motion. The lift component of the drag force is a measure for the anisotropy of the system. We show that due to the realistic director texture the drag force is larger than previously thought and the anisotropy, F
II/F
^, smaller and decreasing while approaching the nematic clearing point.
Three Theorems for the Spectroscopic -Kinetic Analysis of Chemical Reactions
Authors: Mauser H. , Polster J. 
Published: February 2015

Abstract
The results obtained in the last 25-30 years for the spectroscopic-kinetic analysis of reaction systems using absorbance (A) diagrams and the method of formal integration are summarised in three theorems.
Theorem 1: A reaction mechanism can be experimentally disproved but not proved.
Theorem 2: Two strictly linear reaction systems having the same number of linearly independent reaction steps can not be distinguished from each other by purely spectroscopic means.
Theorem 3: Thermally controlled reaction systems which consist of two linearly independent reaction steps -one step of which is at least a reaction of second order -can not be distinguished from each other by purely spectroscopic means if their eigenvalues have the same functional dependence on the initial concentrations.
The advantages of the formalism presented are demonstrated using the photoreduction of anthraquinone-2-carbonic acid in alkaline methanolic solution.
Spin -Orbit Coupling in the O-
2 Anion
Authors: Schiedt J. , Weinkauf R. 
Published: February 2015

Abstract
We could resolve the spin-orbit splitting of 160 ± 4 cm-1 in the 2
II ground state of O2
- anions by high resolution photodetachment photoelectron spectroscopy. The observed splitting is in good agreement with the theoretically derived value. Our directly measured electron affinity of O 2 is 450 ± 2 meV and deviates within experiment errors from previous values. kHz repetition rate was applied to avoid space charge and improve electron energy resolution in a time-of-flight electron energy analyzer.
Spark Gap Pressure and Lasing Behaviour of a non -Blumlein type Nitrogen Laser
Authors: Rodrigues Silvana Vianna , Baumann Wolfram 
Published: February 2015

Abstract
The effect of the nitrogen or SF6 pressure in a spark gap of a small rugged free running nitrogen laser (laser gap 2.4 mm, channel length 170 mm) is studied. No significant difference between nitrogen and SF6 as spark gap chamber gases was found. With increase of the spark gap pressure from 1 to 3.5 bar the pulse energy increases from 30 to 70 μJ, at 10 kV, or from 90 to 130 μJ, at 14 kV. The maximum of the laser efficiency is found at lower breakdown voltages with higher spark gap pressures. Pre-ionization by UV light from the spark gap can be excluded, but not that from a corona discharge over the capacitor foil below the laser channel. It is shown that further effort to increase the laser output power must start from the design of a fast spark gap, well integrated into the whole discharge circuit.
Defect Chemistry of " BaCuO2" I. Oxygen Non -Stoichiometry, Cation Molecularity and X-ray Diffraction Determinations
Authors: Spinolo G. , Anselmi-Tamburini U. , Arimondi M. , Ghigna P. , Flor G. 
Published: February 2015

Abstract
“BaCuO2” is the key intermediate in the synthesis of the Ba2YCu3O7−δ superconductor. Its very complex crystal structure is able to accommodate a large change in oxygen content.
Oxygen non-stoichiometry of "BaCuO2" materials with 1:1 and 88:90 (Ba :Cu) molecularity has been investigated by polythermal X-ray powder diffraction coupled with isobaric-isothermal gravimetry determinations under different temperature and oxygen partial pressure conditions [300≤ T≤ 820 °C, 1 ≥ P(O2) ≥ 3 • 10-3 atm].
The 1:1 composition does not give well reproducible results, thus suggesting its polyphasic nature, at least in part of the investigated range. The results for the 88:90 ≅ 0.98 (Ba :Cu) composi­ tion are well reproducible and show that the material is single phase. Ba0.98CuO1.98 + δ is oxygen over-stoichiometric in the whole investigated [T, P(O2)] range, with a maximum value δ∼0.21. A Rietveld X-ray profile fitting is in agreement with previous single-crystal data. The trend of δ vs. P(O2) is consistent with the presence of oxygen interstitial defects on (possibly different) crystallographic sites.
From Electric Field Dependent Particle Dynamics to Bistability in the Breakdown of the Quantum Hall Effect
Authors: Riess J. 
Published: February 2015

Abstract
The integer quantum Hall effect (IQHE) and its breakdown (onset of dissipation) reflect general properties of the solutions of the time-dependent Schrödinger equation, where the macroscopic elec­tric field E is properly included. In particular, the dynamics of an electron in a broadened Landau band not only depends on the disorder potential but also on the value of |E|. This leads to an I n ­ dependence of the conductivities σxx and σxy, which implies that the IQHE breaks down if |E| is sufficiently high. We show that the general form of the | El-dependence of σxx and σxy can lead to jumps in the longitudinal resistance at the breakdown of the IQHE, as observed in recent experiments.
Investigation of Front Propagation in an Electrochemical System: Experiments and Numerical Simulations
Authors: Flätgen G. , Krischer K. , Ertl G. 
Published: February 2015

Abstract
We examined the spatio-temporal behavior of an electrochemical system in the bistable regime, in which the system might take on either a high current density state (active) or a low current density state (passive) at one value of the externally applied voltage. The transition from the passive to the active state is accompanied by accelerating fronts with sharp interfaces, whereas the reverse transition from the active to the passive state exhibits much smoother spatial variations. Also the evolution of the total current density displays qualitative differences in the two cases. Both, the differences of the spatial patterns as well as those of the total current densities are reproduced with a mathemati­cal model, which also reveals the origin of the asymmetry of the transitions: a global coupling, intrinsic in all electrochemical systems, in combination with the specific dependence of the reaction current on the electrode potential.
Attractor Merging Crisis in the Double-Scroll Oscillator
Authors: Reisner B. , Kittel A. , Lück S. , Peinke J. , Parisi J. 
Published: February 2015

Abstract
We investigate the transition from a mono-scroll to a double-scroll attractor observed in the chaotic dynamics of an electronic oscillator. The description in terms of an attractor merging crisis turns out to be successful. The finding is supported by the topological structure of the attractor and the scaling behavior of the mean residence time.
Dweiltime Analysis of Symmetry-Breaking Dynamical Systems
Authors: Vollmer J. , Peinke J. , Okniński A. 
Published: February 2015

Abstract
Dweiltime analysis is known to characterize saddles giving rise to chaotic scattering. In the present paper it is used to characterize the dependence on initial conditions of the attractor approached by a trajectory in dissipative systems described by one-dimensional, noninvertible mappings which show symmetry breaking. There may be symmetry-related attractors in these systems, and which attractor is approached may depend sensitively on the initial conditions. Dwell-time analysis is useful in this context because it allows to visualize in another way the repellers on the basin boundary which cause this sensitive dependence.
Reversible Control of Chemical Reaction Systems
Authors: Hoff Axel A. , Diebner Hans H. , Baierc Gerold 
Published: February 2015

Abstract
Starting from an algorithm for continuous chaos control, a reversible control method based on mutual diffusive coupling of chemical reactors is developed. With sufficient coupling strength, the proposed mutual coupling leads to control even if both reactors are of similar size. The controlling and controlled reactor exchange their roles at a certain size ratio. Insufficient coupling can lead to a more complex dynamics than that of the uncoupled reactors. This method for control via reversible coupling of chemical reactors should be implementable on a purely microscopic level.
Instabilities in a Simple Enzyme Reaction Caused by pH-Dependence
Authors: Baier Gerold , Strasser Peter , Kummer Ursula 
Published: February 2015

Abstract
We investigate the model of an enzymatic reaction with Michaelis-Menten kinetics and bell-shaped pH-dependence of the reaction rate. In the case of proton consumption the reaction can generate oscillations in a homogeneous reactor and turbulent spatio-temporal patterns in a reaction-diffusion environment. I n s t a b il it i e s in a S im p le E n z y m e R e a c tio n C a u s e d b y p H -D e p e n d e n c e *
EPRInvestigation of Synthetic, Doped FeS2 and RuS2 Single Crystals
Authors: Schüler M. , Dahlem J. , Siebert D. 
Published: February 2015

Abstract
Synthetic FeS2 and RuS2 single crystals were prepared by the flux method using PbCl2, bismut, and tellurium as different solvents. FeS2 and some RuS2 samples were doped with elementary vanadium, other RuS2 crystals with manganese and nickel. The EPR spectra revealed Mn2+ in the low-spin state and Ni2+. The lineshape of the Mn sextet turned out to be asymmetrical. In some RuS2 samples we detected an isotropic structureless rather narrow signal with a linewidth down to 0.05 mT and attributed it to the conductivity. Its lineshape becomes symmetrical and Lorentzian by grinding the samples to a polycrystalline powder. The EPR parameters of appropriate spin-Hamiltonians were determined. The intensities of the allowed and forbidden lines depended very differently on the microwave power due to different degrees of saturation.
Absorption Spectra of Co(II)Ions Doped in Magnesium Thallium Sulphate Hexahydrate
Authors: Subbaiah A. Venkata , Rao J. Lakshmana , Naidu Y. Nagaraja 
Published: February 2015

Abstract
The optical obsorption spectrum of Co(II) ions doped in magnesium thallium sulphate hexahy­ drate is studied at room and liquid nitrogen temperatures. The crystal exhibits characteristic absorption of the Co(II) ion in the visible and near infrared. The observed bands are assigned to transitions from the ground state 4T1g (F) to various excited quartet and doublet levels of the Co(II) ion in octahedral symmetry. The splitting of one of the bands at liquid nitrogen temperature is explained to be due to spin-orbit splitting. All band positions have been fitted by the parameters B, C, Dq and ξ.
Absorption and Fluorescence Properties of p-Substituted Stilbenes in Poly (vinyl chloride) Film
Authors: Kawski A. , Kukliński B. , Nowosielski T. 
Published: February 2015

Abstract
Experimental studies have demonstrated that the absorption and fluorescence spectra of linear molecules with one double bond, i.e. 4-amino-4'-nitrostilbene (ANS), 4-dimethylamino-4'-nitro-stilbene (DNS) and 4,4'-diphenylstilbene (DPS), contained in preheated to 393 K or nonheated polyvinyl chloride) (PVC) films are identical in shape and position, unlike those observed for ANS, DNS and DPS in polyvinyl alcohol) (PVA) films. For polar ANS and DNS molecules in PVC film a decrease in the emission anisotropy with growing wavelength of the fluorescence band was observed. This unusual behaviour of the emission anisotropy is accounted for by the overlap of two close emission bands from different luminescent centres, resulting from different microenvironments of the ANS and DNS molecules in PVC film. The emission anisotropy of nonpolar DPS molecule in PVC does not change within the fluorescence spectrum.
Sub-millimeter Wave Spectra of Cyanoacetylene and Revised Ground State Constants
Authors: Yamada K. M. T. , Moravec A. , Winnewisser G. 
Published: February 2015

Abstract
Sixteen new rotational transitions of cyanoacetylene in the ground vibrational state have been measured in the frequency region from 570 GHz to 710 GHz by the Cologne sub-millimeter wave spectrometer. The observed transition frequencies were analyzed together with unpublished millimeter wave data of our group and with the data available in the literature. Precise rota­ tional constant and the quartic and sextic centrifugal distortion constants have been determined; B = 4549.058224(37) MHz, D = 0.544110(19) kHz, and H = 0.0345(21) mHz.
A Quasi-Optical Multiplier for Terahertz Spectroscopy
Authors: Lewen F. , Belov S. P. , Maiwald F. , Klaus Th. , Winnewisser G. 
Published: February 2015

Abstract
The rotational K-structure (K = 0, ... 6) of the a-type transition (J = 65 - 64) of the symmetric top molecule methylcyanide, CH3CN, has been recorded at 1.2 THz employing a newly designed quasi-optical frequency multiplier. A planar Schottky diode is used as non-linear element for producing the harmonic power and is mounted in the focus of an off-axis antenna across a short single ridged waveguide. The 2nd harmonic of the fundamental frequency is filtered with adichroic plate and is focused onto the InSb bolometer after passing an absorption cell. The multiplier is driven by a high power backward wave oscillator with a fundamental frequency near 600 GHz.
Cation Distribution of ZnFe2O4 and CoFe2O4 Spinels From Anomalous X-Ray Scattering
Authors: Waseda Y. , Shinoda K. , Sugiyama K. 
Published: February 2015

Abstract
The distribution of Zn2+ and Co2+ cations in ferrite spinels has been determined by applying anomalous X-ray scattering (AXS) near the K absorption edges of Fe, Co and Zn. The energy dependence of the reflection intensities of ZnFe2O4, detected at the Fe K and Zn K absorption edges, can only be explained when all Zn2+ being allocated to the tetrahedral site formed by oxygens. On the other hand, the results for CoFe2O4 suggest that 78% of Co2+ occupy the octahedral site, and that the present CoFe2O4 sample is classified as inverse spinel, although a partial disorder is included. The usefulness of this AXS method coupled with the common Rietveld analysis was well-recognized by determining the cation distribution even in a system with next neighboring elements of the periodic table.
Semi-Empirical Fitting of Partial Pair Correlation Functions of Amorphous Alloys
Authors: Sváb E. , Hajdu F. , Mészáros Gy. 
Published: February 2015

Abstract
A semi-empirical fitting procedure has been developed and used in analysing the characteristic features of the partial structure factors of binary amorphous alloys. An analytical formula is given to fit the experimental atomic pair correlation function as a sum of Gaussians. The inverse Fourier transform of the fitted terms reproduces all features of the experimental structure function. In addition to the structural parameters, the modelling gives a quantitative explanation for the complex origin of characteristic features in the diffraction pattern such as pre-peak, pre-minimum, and split peaks in the partial structure factor.
Tunable Real Space Transfer Oscillator by Delayed Feedback Control of Chaos
Authors: Cooper D. P. , Schöll E. 
Published: February 2015

Abstract
It is demonstrated numerically that by using Pyragas' method of chaos self-control a stable semiconductor oscillator can be designed based on driven real-space transfer oscillations in a modulation-doped heterostructure. By application of a small time-continuous delayed feedback voltage control signal, different unstable periodic orbits embedded in the chaotic attractor can be stabilized. Thus different modes of self-generated periodic voltage oscillations can be selected by choosing an appropriate delay time. This provides tunability to different discrete frequencies.
Explosive Instability in Superposed Fluids in Hydromagnetics
Authors: Gill Gurpreet K. , Trehan S. K. 
Published: February 2015

Abstract
We study the resonance interaction between two marginally unstable modes of small but finite amplitude waves in the Kelvin-Helmholtz flow model using the method of multiple scales. We find that, as magnetic field increases, the amplitudes of the disturbance diverge at a very high rate while for a fluid of higher density ratio e, the amplitudes diverge very slowly.
The 33S Nuclear Quadrupole Hyperfine Structure in the Rotational Spectrum of 32S, 33S Dimethyl Disulfide
Authors: Hartwig H. , Kretschmer U. , Dreizler H. 
Published: February 2015

Abstract
We investigated the rotational spectrum of 32S, 33S dimethyl disulfide in natural abundance by molecular beam Fourier transform microwave spectroscopy. We were able to determine the com­plete 33S quadrupole coupling tensor, the rotational and centrifugal distortion constants and the internal rotation parameters of the two methyl tops. The rotational constants were found to be A = 8113.8847(23) MHz, B = 2800.6203(30) MHz and C = 2557.2245 (32) MHz. The results are compared with former publications.