bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamics and Structure of Isothiocyanate Complexes of Manganese(II), Cobalt(II) and Zinc(II) Ions in N,N-Dimethylacetamide
Authors: Koide Makoto , Ishiguro Shin-ichi 
Published: February 2015

Abstract
The complexation of manganese (II), cobalt (II) and zinc(II) with thiocyanate ions has been studied in N,N-dimethylacetamide (DMA) by calorimetry and spectrophotometry at 298 K. In these metal systems the formation of a series of four isothiocyanato complexes, [M(NCS)n](2-n)+ (n = 1÷4; M = Mn, Co, and Zn) was established, and their formation constants, enthalpies and entropies were determined. Interestingly, the complexation behavior in DMA is significantly different from that in N,N-dimethylformamide (DMF), despite of the similarity of the physicochemical properties of these solvents. The complexation is indeed enhanced significantly in DMA over DMF and is more exothermic in the former solvent. Furthermore, with cobalt(II) an octahedral to tetrahedral coordination geometry change was found to occur in DMA at an earlier step of complexation than in DMF. These results suggest that six-coordination of DMA molecules to a metal ion is severely sterically hindered.
Structure of the Solvated Strontium and Barium Ions in Aqueous, Dimethyl Sulfoxide and Pyridine Solution, and Crystal Structure of Strontium and Barium Hydroxide Octahydrate
Authors: Persson Ingmar , Sandström Magnus , Yokoyama Haruhiko 
Published: February 2015

Single crystal X-ray data, collected at 298 K, are used to redetermine the crystal structure of the non-isomorphic compounds [Sr(H2O)8](OH)2 and [Ba(H2O)8](OH)2. The eight water oxygen atoms form distorted Archimedean antiprisms around the octahydrated metal ions with mean metal ion-oxygen distances 2.62 and 2.79 Å for strontium and barium, respectively. A second coordination shell of 24 hydrogen-bonded oxygen atoms with mean metal ion-oxygen distances M…OII 4.76 and 4.80 Å, respectively, is observed. The hydroxide ions in both structures have an unusual hydrogen bond arrangement with 5 bonds accepted and one donated.
The structure of the solvated strontium and barium ions in aqueous, dimethyl sulfoxide and pyridine solutions has been studied by means of large angle X-ray scattering and extended X-ray absorption fine structure spectroscopy techniques. In aqueous solution independent determinations of the first-sphere metal-oxygen coordination by the two techniques resulted in the bond lengths Sr-O 2.63 (2) and Ba-O 2.81 (3) Å, and for both metal ions a hydration number of 8.1 (3). The second coordination spheres are very diffuse with only about 13 water molecules at similar M…OII distances as in the crystal structures and 2-3 water molecules closer to the metal ions. In dimethyl sulfoxide solution both ions were found to coordinate 6.0 (5) solvent molecules with the distances Sr-O 2.54(1), Sr…S 3.77(1) Å, and Ba-O 2.76(1), Ba…S 3.99(1) Å. For the solvated ions in pyridine solution EXAFS measurements yielded the distances Sr-N 2.57 (2) and Ba-N 2.78 (3) Å, with a probable solvation number of 6.
Correlations of hydration enthalpies and partial molar volumes with experimental M-O bond distances in aqueous solution are used to discuss hydration numbers and bond character for all of the alkaline earth metal ions.
Ist 91Zr-Festkörper-Kernresonanzspektroskopie praktikabel?
Authors: Hartmann P. , Scheler G. 
Published: February 2015

Abstract

91Zr solid state NMR spectra have been observed for samples possessing different zirconium local-site environments (e.g. phosphates, fluorides). Depending on the quadrupole coupling, different NMR experiments have been utilized. In case of weak quadrupole coupling, magic angle spinning (MAS) is suitable. Otherwise, spin echo techniques are necessary to overcome “acoustic ringing’’ and receiver dead-time limitations. Using the step echo method, the detection of the very broad 91Zr signals is not limited by non-uniform spectral excitation. The obtained 91Zr chemical shifts range from -246 ppm to 208 ppm, the quadrupole coupling frequencies from 50 kHz to 2.7 MHz..
Creation and Recombination of Frenkel Defects in AgBr
Authors: Funke K. , Lauxtermann T. , Wilmer D. , Bennington S. M. 
Published: February 2015

Abstract
Complete ionic conductivity spectra as well as quasielastic and inelastic neutron scattering spectra have been taken of solid silver bromide at various temperatures. High-amplitude vibrational move­ments, essentially of the silver ions, contribute to both kinds of spectra. In particular, a conductivity maximum, located at about 500 GHz, reflects oscillations of individual silver ions along directions. -The microwave and millimetre-wave conductivities are dominated by a thermally activated Debye-type relaxation process. The effect is consistently explained by the frequent hopping of silver ions from regular octahedral lattice sites into tetrahedral interstitial sites and back again, i.e., by the frequent creation and recombination of Frenkel pairs. -The effect is also responsible for the existence of thermally activated quasielastic components in the neutron scattering spectra. The width of the coherent quasielastic scattering shows that the forward-backward hopping of a silver ion is accompanied by fast correlated movements of ions in its immediate neighbourhood.
Some Aspects of Spinodal Decomposition in Spinel Solid Solutions
Authors: Burkert N. , Grüne R. , Schmalzried H. , Rahman S. 
Published: February 2015

Abstract
Decomposition morphologies of supersaturated spinel solid solutions in the quasi-binary system Co2TiO4-CoAl2O4 at 973 K show all pertinent features of spinodal decomposition. Since the decomposition morphology may not be considered as sufficient evidence for a spinodal process, the thermodynamics of the spinel solid solutions and the linear transport theory of spinodal decomposition were combined to corroborate the experimental results of the early decomposition reaction.
Simultaneous ordering, a common property of ternary and higher nonequilibrium solid solutions, was also observed. These ordering processes occur locally in distinct regions of the spinel crystal. Moreover, the spinodal wavelength λ increases in time according to λ ∞ t, which is unusual and will be discussed in the light of cation diffusion in semiconducting oxides with two cation sublattices.
SIMS Investigations on the SmCo5Dnand LaNi5HnSystems
Authors: Dobrileit R. , Züchner H. 
Published: February 2015

Abstract
Characteristic secondary ion emission patterns of several metal-hydrogen systems have been measured by SIMS to get information about the metal-hydrogen bonding and the structure of these systems. Results on SmCo5Dn and LaNi5Hn, and on H-D-loaded samples of the pure components are presented. The emission patterns of the secondary ions show a stronger bonding of hydrogen to Co and Ni than to Sm and La, although these transition metals, contrary to Sm or La, do not form stable hydrides under normal conditions. In these AB5-compounds the transition metal seems to be transformed to a "hydride forming material" due to the presence of the rare earth element. The secondary ion emission patterns of the hydrogen loaded intermetallics are explained and compared to those of the hydrogen loaded pure components.
The similarity in the secondary ion emission patterns of the SmCo5Dn and LaNi5Hn systems points to a general characteristic of AB5Hn materials.
Proton Diffusion in Strontium Cerate Ceramics studied by Quasielastic Neutron Scattering and Impedance Spectroscopy
Authors: Karmonik Ch. , Hempelmann R. , Matzke Th. , Springer T. 
Published: February 2015

Abstract
Perovskite structured strontium cerate doped with ytterbium and water, e.g. SrCe0.95Yb0.05 H0.02O2.985, is a well known proton conductor at elevated temperatures. We have studied its proton conductivity or diffusivity, respectively, by impedance spectroscopy, IS, and by quasielastic neutron scattering, QENS. While the former method yields a macroscopic proton diffusion coefficient, the latter method allows to elucidate the microscopic proton diffusion mechanism. It consists of a sequence of free diffusion and trapping/escape events with the Yb3+ ions acting as trapping centers. The self-diffusion coefficient obtained with QENS agrees with the conductivity diffusion coefficient obtained with IS.
Decomposition of Plane Waves into Irreducible Representations of Space Groups
Authors: Teuscher H. , Kramer P. 
Published: February 2015

Abstract
Using a relation between representation theory of crystallographic space groups and a Dirichlet type of boundary problem for the Laplacian, we derive the solutions for the Dirichlet problem, as well as for a similar Neumann boundary problem, by a complete decomposition of plane waves into irreducible representations of a particular space group. This decomposition corresponds to a basis transformation in L2(Ω) and yields a new set of basis functions adapted to the symmetry of the lattice considered.
Molecular Motion in Solid Tetraethyl -and Tetrapropylammonium Tetrafluoroborates
Authors: Szafrańska Barbara , Pająk Zdzisław 
Published: February 2015

Abstract
Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetraethyl-and tetrapropylammonium tetrafluoroborates have been measured over a wide range of temperatures. Solid-solid phase transitions were found for both compounds and confirmed by DSC. Methyl group C3 reorientation followed by more complex cation motions was evidenced in the low temperature phases. Overall cation reorientation characterises the high temperature phases of both compounds. Isotropic anion reorientation was found in both salts in both phases.
Dielectric Relaxation Studies of 5PCH by the Time Domain Spectroscopy Method
Authors: Gestblom Bo , Urban Stanislaw 
Published: February 2015

Abstract
The time domain spectroscopy (TDS) method has been used for the measurement of the complex dielectric permittivity in the isotropic phase and for perpendicular and parallel orientations in the nematic phase of 5PCH (4-(trans-4-pentyl-cyclohexyl)-benzonitrile). The accessible frequencies range from ca 15 MHz to ca. 1.5 GHz. The obtained spectra are well consistent with the spectra measured recently in the frequency domain (T. Brückert et al., Mol. Cryst. Liq. Cryst., in press). From the relaxation times τ‖, τ⊥and τis we have calculated the activation enthalpies and the retardation factors g|| and g⊥ that allow to obtain the nematic potential q. The validity of some assump­ tions of the mean-field theories of the nematic state are discussed.
Quantum Mechanics Derived from Boltzmann's Equation for the Planck Aether
Authors: Winterberg F. 
Published: February 2015

Abstract
In the Planck aether hypothesis it is assumed that space is densely filled with an equal number of locally interacting positive and negative Planck masses obeying a nonrelativistic law of motion. If described by a quantum mechanical two-component nonrelativistic nonlinear operator field equation, this model has a spectrum of particles greatly resembling the particles of the standard model, with Lorentz invariance as a derived dynamical symmetry valid in the limit of energies small com­ pared to the Planck energy.
Here we show that quantum mechanics itself can be derived from the Newtonian mechanics of the Planck aether as an approximate solution of the Boltzmann equation for the positive and negative Planck masses, with departures from quantum mechanics suppressed by the Planck length.
Action Integrals for Ellipsoidal Billiards
Authors: Richter Peter H. , Wittek Andreas , Kharlamov Mikhail P. , Kharlamov Alexej P. 
Published: February 2015

Abstract
Integrable billiards in ellipsoidal and related shapes are discussed. The emphasis is on the computation and graphic presentation of energy surfaces in the space of action variables. Explicit results, including figures, are given for spheres, circular cylinders, planar ellipses, prolate and oblate ellipsoids.
81Br Nuclear Quadrupole Relaxation in Aluminium Tribromide
Authors: Okubo Noriaki , Igarashi Mutsuo , Yoshizaki Ryozo 
Published: February 2015

Abstract
The 81Br nuclear spin-lattice relaxation time in AlBr3 has been measured between 8 K and room temperature. The result is analyzed using the theory of the Raman process based on covalency. A Debye temperature of 67.6 K and covalency of 0.070 and 0.072 for terminal and 0.022 for bridging bonds are obtained. The correspondence of the latter values to those obtained from the NQR frequencies is low, in contrast to the previously examined compounds.
1H and 19F NMR Study of Cation and Anion Motions in Guanidinium Fluoroantimonates
Authors: Grottel M. , Kozak A. , Pająk Z. 
Published: February 2015

Abstract
Proton and fluorine NMR linewidths, second moments, and spin-lattice relaxation times of polycrystalline [C(NH2)3]2SbF5 and C(NH2)3SbF6 were studied in a wide temperature range. For the pentafluoroantimonate, C3-reorientation of the guanidinium cation and C4-reorientation of the SbF5 anion were revealed and their activation parameters determined. The dynamical inequivalence of the two guanidinium cations was evidenced. For the hexafluoroantimonate, two solid-solid phase transitions were found. In the low temperature phase the guanidinium cation undergoes C3 reorien­ tation while the SbF6 anion reorients isotropically. The respective activation parameters were derived. At high temperatures new ionic plastic phases were evidenced.
Structure and Dynamics of Crystal Solvates Hexaphenylditin • 2X, X=Benzene , Toluene, Fluorobenzene , Chlorobenzene , and Aniline. An X-Ray, P(VAPOR)=ƒ(T)> and 2H NMR Study
Authors: Eckardt Karin , Fuess Hartmut , Hattori Masakazu , Ikeda Ryuichi , Ohki Hiroshi , Weiss Alarich 
Published: February 2015

Abstract
The crystal structures of the hexaphenylditin (hpdt) solvate compounds, (C6H5)3Sn-Sn (C6H5)3 • 2X, solvent X = aniline (an), chlorobenzene (cb), fluorobenzene (fb), and toluene (to), were determined. They are isomorphous with the known benzene (be) crystal solvate compound hpdt • 2be, crystallizing in the trigonal space group R3̅, with Z=3 formula units per unit cell. The lattice constants (in pm), from X-ray powder diffraction, are: hpdt • 2an (1): a= 1170.01 (9), c = 2641.49 (20), c/a = 2.2577; hpdt • 2be (2): a = 1165.45 (5), c = 2641.30 (9), c/a = 2.2663; hpdt • 2cb (3): 0=1175.88(5), c = 2661.66(10), c/a = 2.2635; hpdt • 2fb (4): 0 = 1167.69(5), c = 2643.21 (9), c/a = 2.2636; hpdt • 2to (5): a=1182.24 (7), c = 2649.13(11), c/a = 2.2408. The single crystal structure determination of 5 leads to a = 1180.2(2), c = 2651.4 (5). The decomposition of 5 results in the monoclinic phase of hexaphenylditin. Vapor pressure measurements p=ƒ(T), 260 <̲ T/K <̲350, of the compounds have been performed and the heats of vaporization ΔHv/kJmole-1 were determined: 52.44 (1), 46.65 (2), 34.52 (3), 43.08 (4), 55.30 (5). The dynamics of the host molecules C6D6, C6D5CD3 and C6H5ND2 were studied by 2H NMR in the range 295 <̲ T/K <̲ 118. The rotation of the benzene molecule about its threefold axis is maintained till 118 K; in the case of toluene the rotation of the phenyl ring about the pseudo-threefold axis freezes in below 180 K, while the methyl group still rotates about its threefold axis till 123 K.
Direct Determination of the Local Structure in Molten Alumina by High Temperature X-Ray Diffraction
Authors: Waseda Y. , Sugiyama K. , Toguri J. M. 
Published: February 2015

Abstract
A high temperature X-ray diffraction study of molten alumina has been carried out at 2363 K (2090°C). The local ordering parameters in molten alumina were estimated by using the interference function refining technique. Octahedrally coordinated aluminum is suggested to remain in the melt as the fundamental local structure.
Comparison of ESR Spectra of Two Cu(II) Salts in Some Amide Solutions
Authors: Robers B. , Stockhausen M. 
Published: February 2015

Abstract
X-band ESR spectra of liquid solutions of Cu(II)nitrate and Cu(II)chloride in N-methyl-formamide and four N,N-disubstituted amides are reported and discussed with respect to the occurrence of ion pairs or higher ionic aggregations. Nitrate solutions allow to distinguish two complex types of moderate asymmetry at most. Chloride solutions indicate a succession of at least three complex types with strongly increasing asymmetry.
Static Permittivity and Association in Mixtures of Mono- and Dihydric Alcohols
Authors: Hanna F.F. , Shafik A.H. , Stockhausen M. 
Published: February 2015

Abstract
The static permittivity has been measured for n-hexanol and n-dodecanol in heptane solution on admixture of a mi­ nor (fixed) fraction of a dihydric alcohol (ethanediol, 1,6-hexanediol or 1,12-dodecanediol) from low to medium total alcohol concentrations. The 20°C dispersion steps are re­ ported. They show a more or less pronounced intensification due to the additive, which unexpectedly is smaller on addi­tion of two diols together than of only one diol. Probably this reflects competing self- and hetero-association equilibria.
Bubble Formation in Superposed Magnetic Fluids in the Presence of Heat and Mass Transfer
Authors: Gill Gurpreet K. , Chhabra R.K. , Trehan S.K. 
Published: February 2015

Abstract
In this paper we study the nonlinear Rayleigh-Taylor instability in the case of magnetic fluids in the presence of heat and mass transfer. We find that there is a normal field instability in the linear case. The behaviour of the bubbles in the nonlinear analysis is the same as if they were leaving the surface when the liquid is superheated. The criterion for "Explosive Instability" is also examined.
Pressure Dependence of the Dielectric Anisotropy of 5CB and 6CB
Authors: Urban Stanislaw 
Published: February 2015

Abstract
The pressure-dependence of the dielectric anisotropy, Δε = ε0|| - ε0⊥, of two nematogens, n-pentyl-and n-hexyl-cyanobiphenyl (5CB and 6CB) has been measured at constant temperature. For this purpose a high pressure chamber made of non-magnetic materials was constructed, allowing for the orientation of the samples by a magnetic field. The pressure dependencies of ΔεT were analyzed in the frame of the Maier-Meier equations for the principal permittivity components in the nematic phase. It was found that the relation between Δε and the order parameter S is not properly described by these equations. The Kirkwood correlation factor calculated on the basis of the present results and the Maier-Meier equations is smaller than 0.5, whereas it increases to a more realistic value (~0.7) if the electronic polarization is incorporated in the equations.
X-Ray Diffraction with Molten AuxMn100-x-Alloys
Authors: Hagenmayer R. M. , Lamparter P. , Steeb S. 
Published: February 2015

Abstract
The molten alloys Au28.5Mn71.5 and Au68Mn32 are investigated with the energy dispersive X-ray diffraction method which works rather fast so that the evaporation loss of Mn from the molten alloys is kept low. From the observed prepeak follows that both melts are compound-forming but the gold rich melt Au68Mn32 shows only 50% of the short range order existent within the Au28.5Mn71.5 melt. Total structure factors and total pair correlation functions are discussed.
NMR and FTIR Characterization of Sol-Gel Derived Ternary Oxide Glasses in the System BaO–TIO2–SiO2
Authors: Feike M. , Meise-Gresch K. , Chen Qi , Frischat G.H. 
Published: February 2015

Abstract
The annealing history of glasses in the system (20-40) BaO-40TiO2(40-20)SiO2 has been mon­itored by 29Si MAS NMR and FTIR spectroscopy from the dried gel to the final glassy state. Assignment of chemical shifts to specific building units has been facilitated by comparative studies of the limiting less complex binary silicate systems. From the NMR spectra at various compositions appreciable condensation to a three-dimensional network is inferred already at low drying temper­atures. Processes like the pyrolysis of acetate rests of the starting materials and modification of the silicate structure due to Ba2+ cations have been mirrored in the spectra of both methods for samples annealed at intermediate temperatures. The microstructure of the final gel glass of the ternary system has been determined spectroscopically to consist of silicate and titanate species typical of crystalline fresnoite, whereas remaining amounts of TiO2 and SiO2 develop a separate network each. Only small amounts of Si-O-Ti linkages have been recognized in the vibrational absorptions; they vanish at higher annealing stages.
Nuclear Magnetic Resonance Measurements in Oil-Nitrogen Two-Phase Flow
Authors: Krüger G. J. , Birke A. 
Published: February 2015

Abstract
NMR measurements of the oil mass flow have been carried out in all-oil flow as well as in oil-nitrogen two-phase flow. For the calibration a simplified method was used which circumvents spin-lattice relaxation calculations due to the short polarization time of the protons at rather high flow velocities. With this method an overall accuracy of the oil-flow in oil-nitrogen two-phase flow of about ±5% was achieved.
Some proposals for an improvement of the NMR apparatus are made, which would render the evaluations simpler and more accurate.
Enumeration of the Staggered Conformers of Alkanes
Authors: Cyvin S.J. , Brunvoll J. , Cyvin B.N. , Lüttke W. 
Published: February 2015

Abstract
Alkanoid systems are chemical graphs which can be embedded in the diamond lattice. They correspond to the staggered conformers of alkanes. Non-overlapping and overlapping systems are defined. The previously deduced algebraic solution for the numbers of unbranched alkanoids is revisited and reformulated in terms of generating functions. Computerized enumerations for non-overlapping alkanoids, both unbranched and branched, are reported. Some of the smallest overlap­ ping unbranched alkanoids are generated by a method called combinatorial constructions.
Influence of Temperature and Oxygen Concentration on the Radiation Induced Oxidation of Phenylalanine
Authors: Krajnik P. , Quint R. M. , Solar S. , Getoff N. , Sontag G. 
Published: February 2015

Abstract
The formation of tyrosine isomers by γ-radiolysis of neutral aqueous phenylalanine solutions was found to be strongly dependent on oxygen concentration and temperature. Changing the dose rate did not influence the degradation process. In the presence of 0.25 x 10-3 mol dm-3 oxygen at room temperature the yields of o-tyrosine as well as of m- and p-tyrosine drop from G(o-Tyr) = 0.5 and G(m-Tyr) = G(p-Tyr) = 0.4 at a dose of 0.3 kGy to 0.18 and 0.16 at 2.5 kGy, respectively. In solutions containing 1.25 x 10-3 mol dm-3 oxygen the initial yields remain unchanged but decrease at 2.5 kGy only to G(o-Tyr) = 0.3 and G(m-Tyr) = G(p-Tyr) = 0.20. Under the latter reaction conditions also 3,4-dihydroxyphenylalanine was found.
Samples irradiated in frozen state did not show remarkable radiolysis of phenylalanine and tyrosine formation. In the range between 5 and 20°C no essential influence of temperature on the phenylalanine radiolysis and tyrosine yields was observable. The obtained results are important for methods using the tyrosine yields as markers for the detection of irradiated food. Storage conditions and irradiation temperature play an essential role on radiation induced changes of food.
Phase Diagrams of Binary Systems of Some Alkali Iso–Butyrates with One Mesogenic Component
Authors: Mirnaya T. A. , Yaremchuk G. G. , Volkov S. V. 
Published: February 2015

Abstract
The phase diagrams of the binary mixtures of mesogenic potassium iso-butyrate with non-mesogenic lithium-, sodium-, and caesium iso-butyrate have been investigated by differential thermal analysis and hot stage polarization microscopy. The temperature and concentration ranges of liquid crystal formation have been established. Sodium and caesium iso-butyrate have been found to possess latent mesogenic properties.