bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric Relaxation Studies of 4-n-Alkyloxy-4’-Cyanobiphenyls (nOCB, n= 5÷8)
Authors: Urban S. , Gestblom B. , Kresse H. , Dąbrowski R. 
Published: February 2015

Abstract
The results of dielectric relaxation studies of series of four n-alkyloxy cyanobiphenyl (nOCB) compounds with n ranging from 5 to 8 are presented. The complex dielectric permittivity, ε*(ω) - ε’(ω) - i ε’’(ω), was measured in the frequency range 1 kHz - 3 GHz, with the use of an impedance analyzer and a time domain spectroscopy (TDS) set-up. The relaxation times: longitudinal τ|| in the nematic and smectic A phase (80CB), transverse τ⊥ in the nematic phase, and τis in the isotropic phase, were obtained as functions of the temperature. This allowed the calculation of activation barriers for different molecular relaxation processes occurring in particular phases. More-over, the retardation factors g|| and g⊥ and the nematic potential q according to two theoretical models were calculated. The analysis of q(T) and its relation to the order parameter S is done taking into account the results of NMR studies of the compounds under consideration. Finally, the dependencies of the obtained quantities on the number of carbon atoms in the alkyloxy chains are analyzed.
Analysis of the FTIR Bands v11 and v8 of 1,1-difluoroethylene with Rotational Background Information on Excited States
Authors: Stiefvater Otto L. 
Published: February 2015

Abstract
Much earlier work on the analysis of the fundamental infrared bands v11 and v8 of 1,1-difluo-roethylene has been resumed and extended.
The Q-branch of the C-type band v11 ~ 802 cm-2 has been analysed, and sextic distortion constants have been obtained for v8 = 1 at ~ 1301 cm-1 . The rotational constants of the two states are found to differ noticeably (20-100 standard deviations) from values reported earlier.
The discrepancies are believed to result in part from the availability of purely rotational data on v n and v 8 in the present study, but to originate primarily from the adoption of rather poor values of the ground state constants of 1,1-difluoroethylene in the earlier work on these two fundamentals.
Phase Diagram of the Orientationally Order-disorder Binary System 2,2-dimethyl-1,3-propanediol / 2,2-dimethyl-1,3-diaminopropane, [(CH3)2 C(CH2OH)2]x [(CH3)2C(CH2NH2)2]1-x · A Thermodynamic, X-ray, and 1H-NMR study
Authors: Strauss Roman , Braun Sigmar , Dou Shi-qi , Fuess Hartmut , Weiss Alarich 
Published: February 2015

Abstract
The phase diagram of the binary system [2,2-dimethyl-1,3-propanediol]x (1) / [2,2-dimethyl-1,3- diaminopropane]1-x (2) was studied by X-ray diffraction and DTA/DSC, for (2) also by 1H-NMR. The system is miscible over the whole concentration range 0 ≤ x ≤ 1 in the liquid state and in the plastic solid state, phase I, just below the melting point. At lower temperatures the system is demixing, and at room temperature two plastic mixed crystals coexist. The plastic phases of (1), (2), and (l)x(2)1-x crystallize face centered cubic, Fm3m, Z = 4, the lattice constants decreasing linearely with increasing x, and the lattice constants are: (1) a(327K) = 880.3 pm , (2) a(243K) = 905.6 pm. By single crystal X-ray diffraction the structure of the ordered phase II of (1) was refined at room temperature, monoclinic, P21/n, Z = 4, a = 596.9 pm, b = 1090.2 pm, c = 1011.0 pm, β = 99.74°. The results are in good agreement with the literature. The phase transition temperatures (in Kelvin) are T1→m = 399.2, TMm→1 = 399.7, T11→1 = 316.2, T1→11 = 308.2 for (1); = 300.2, = 301.7, T11→1 = 228.7, T1→n = 194.2 for (2). Strong hysteresis is observed for the transition T1→11 in (2). In the mixed systems (1)x(2)1-x, 0 < x < 1, the disordered phases do not order even by quenching to liquid nitrogen temperature. High resolution 1 H-NMR measurements are reported for phase I of (2) as a function of temperature. The “liquid” 1H-NMR spectrum is present far below the thermodynamic phase transition temperature T11-1, overlapping the wide line unresolved powder spectrum of phase II.
Notiz: Quantification of Symmetry
Authors: Novak Igor 
Published: February 2015

Abstract
A new mathematical criterion is suggested for symmetry ranking, i.e. determination of an “absolute symmetry scale” for discrete, finite groups. The criterion is based on both, the periods (orders) of each group element and the order of the group itself. This is different from the current criteria which consider only the orders of the groups themselves. The symmetry ranking, based on the new criterion, is applied to the symmetry point groups.
Investigation of the Reaction between Fe2O3 and Si Activated by Ball Milling
Authors: Concas Giorgio , Congiu Francesco , Corrias Anna , Muntoni Carlo , Paschina Giorgio , Zedda Daniela 
Published: February 2015

Abstract
The path of the reaction between Fe2O3 and Si, activated by high energy ball milling, has been investigated by X-ray diffraction and Mössbauer spectroscopy. Hematite reduction involves oxygen transfer from Fe to Si with the formation of intermediate phases containing Fe(II), which are then reduced to Fe(0). A steady state is reached in the milling process where the reduction of stoichiometric amounts of Fe2O3 and Si is not complete and an amount of Fe(II) in an amorphous matrix still remains. The same intermediate compounds are also observed in the milling process of mixtures with higher Fe2O3 /Si molar ratio.
The Microwave Spectrum of trans-2,3-Dimethyloxirane in Torsional Excited States
Authors: Hartwig H. , Dreizler H. 
Published: February 2015

Abstract
The microwave spectrum of trans-2,3-dimethyloxirane (CH3CHOCHCH3) in the excited tor-sional states υ17 = 1 and υ33 = 1 has been measured in the range from 8 to 26 GHz and assigned. An analysis of internal rotation splittings of the observed rotational transitions was performed using the internal axis method (or "combined axis method") with a newly developed program accounting for the top-top coupling. The threefold hindering potential V3 and the direction cosines λ g,i of the internal rotation axes i with respect to the principal inertia axes g are in a good agreement with the ground state values. Additionally, the sixfold hindering parameter V6 was found to be - 0.2600(12) kJ/mol. The value of the parameter V′12 describing the top-top coupling in the potential function (via V′12 sin 3 τ1 sin 3 τ2), was determined to -0.4240(6) kJ/mol.
Dielectric Behaviour of 1-(4-Isothiocyanatophenyl)-2-(4-hexyl- bicyclo[2,2,2]octane-1)ethane in Nematic and Isotropic Phases
Authors: Jadżyn J. , Legrand C. , Kędziora P. , Żywucki B. , Czechowski G. , Bauman D. 
Published: February 2015

Abstract
Static and dynamic investigations of the dielectric properties of the liquid crystal 1-(4-isothio-cyanatophenyl)-2-(4-hexyl-bicyclo[2,2,2]octane-1)ethane in the nematic and isotropic phases have been carried out in the frequency region from 1 kHz to 1 GHz. Two relaxation processes, described by the Debye functions, have been observed not only in the isotropic but also in the nematic phase, when the measurements of the electric permittivity vs. frequency have been made parallel to the orientation axis of liquid crystal. These processes are related to the rotation of the permanent dipole moment around two main molecular axes. The height of the potential barrier which hinders the rotation of the liquid crystal molecule around the short axis in the ordered nematic phase and the order parameter of the liquid crystal investigated have been estimated on the basis of the relaxation time values in the nematic and isotropic phases.
β-cyclodextrine and Water: Semiempirical Calculations
Authors: Margheritis C. , Sinistri C. 
Published: February 2015

Abstract
AM1 and PM3 calculations were carried out on ß-cyclodextrine (ß-CD) undecahydrate in the experimental conformation at 120 K. The calculated ß-CD/water interaction energies are very small and indicative for each water molecule of an unfavorable condition in respect to that of pure water. The conformationally optimized system was also studied: ß-CD appears highly symmetrical with negligible dipole moment, mainly because of the circular arrangement of the single vectors. Primary hydroxyls can easily rotate, while the secondary ones are stabilized by heteroannular hydrogen bonds and homoannular electrostatic interactions due to the consequent increase of the atomic charges. The ß-CD/water interaction energies in the optimized hydrated system are not significantly different from the experimental ones. This almost hydrophobic character is also shown by MM equilibrated solutions: all water molecules are rejected beyond 2.4 Å; between 2.4 and 2.9 Å highly structured water is present. From a purely enthalpic standpoint the molecule hydration appears highly improbable, thus the formation of ß-CD 11 H20 must involve a compensation mechanism.
Non-Linear Generalization of the Relativistic Schrödinger Equations
Authors: Ochs U. , Sorg M. 
Published: February 2015

Abstract
The theory of the Relativistic Schrödinger Equations is further developped and extended to non-linear field equations. The technical advantage of the Relativistic Schrödinger approach is demonstrated explicitly by solving the coupled Einstein-Klein-Gordon equations including a non-linear Higgs potential in case of a Robertson-Walker universe. The numerical results yield the effect of dynamical self-diagonalization of the Hamiltonian which corresponds to a kind of quantum de-coherence being enabled by the inflation of the universe.
Ion Acoustic Soliton in an Electron Beam Plasma
Authors: Chatterjee Prasanta , Roychoudhury Rajkumar 
Published: February 2015

Abstract
The pseudopotential method is used to study ion acoustic compressive and rarefactive solitons in an electron beam plasma with hot isothermal electron beam and plasma electrons and warm ions. It is shown that for small amplitude cases our results completely agree with the published results.
A Fundamental Structure of Continuum Mechanics I. Elastic Systems
Authors: Stuke Bernward 
Published: February 2015

Abstract
Continuum mechanics and thermodynamics are complementary areas of classical field theory. Their fundamental structure, however, is rather different according to the present view: on the one hand there is the equation of motion or the equivalent balance of momentum, on the other there is Gibbs' fundamental equation.
In a preceding paper it has been shown that systems having a potential of acceleration possess a structure of continuum mechanics which corresponds to the one of thermodynamics. This discussion is extended to elastic systems. In this case a tensorial potential of acceleration must be introduced. The equation of motion derived for this extended structure contains two additional terms (reactive forces) not present in the conventional balance of forces.
A Theoretical Study on Intramolecular Cyclization of Azidobenzotriazine to Tetrazolobenzotriazines
Authors: Asaad Adel N. , El Ashry El Sayed H. 
Published: February 2015

Abstract
The cyclization equilibrium of 3-azidobenzo[l,2,4]triazine (1 a) with tetrazolo[5,1-b]benzo[1,2,4] triazine (linear isomer, 1 b) and tetrazolo[5,1-c]benzo[1,2,4]triazine (angular isomer, 1 c) is investigated computationally using the molecular orbital MNDO-SCF method. The results suggest that the higher reactivity of atom N(4) with respect to N(2) towards the cyclization is due to: (i) The negative charge density upon N(4) is 1.3 time larger than that upon N(2); (ii) In the highest occupied molecular orbital (HOMO) the coefficient at N(4) is 2.4 times larger than that at N(2); (iii) The heat of reaction to (1 c) and (1 b) are calculated to be -74.9 and -14.8 kJ mol -1 , respectively; (iv) The thermodynamic stabilization of the angular isomer (1 c) is 60.1 kJ mol-1 larger than that of the linear isomer (1 b), and (v) The potential barrier heights calculated for the cyclization favour the angular product. From these considerations and the perturbation theory, the calculated yield of the cyclization reaction is 70.8±0.1% of 1 c, which is in good agreement with the experimental yield 64%.
Rayleigh-Taylor Instability of Viscous-Viscoelastic Fluids in Presence of Suspended Particles Through Porous Medium
Authors: Kumar Pardeep 
Published: February 2015

Abstract
The Rayleigh-Taylor instability of a Newtonian viscous fluid overlying an Oldroydian viscoelastic fluid containing suspended particles in a porous medium is considered. As in both Newtonian viscous-viscous fluids the system is stable in the potentially stable case and unstable in the potentially unstable case, this holds for the present problem also. The effects of a variable horizontal magnetic field and a uniform rotation are also considered. The presence of magnetic field stabilizes a certain wave-number band, whereas the system is unstable for all wave-numbers in the absence of the magnetic field for the potentially unstable configuration. However, the system is stable in the potentially stable case and unstable in the potentially unstable case for highly viscous fluids in the presence of a uniform rotation.
An EPR Study on VO2+ and Mn2+ Ions in Some Zeolites
Authors: Ucun F. , Köksal F. 
Published: February 2015

Abstract
The electron paramagnetic resonance (EPR) of hydrated VOSO4 ·3H2O and MnCl2 · 2H2O, adsorbed on the synthetic zeolites 3A, 4A, 5A and 13X of pore diameters 0.3, 0.4, 0.5, and 1.0 nm, respectively, and the natural zeolites heulandite and clinoptilolite was investigated. The spectra indicated that the coordination structures are VO(H2O)5
2+ and Mn(H2O)6
2+ , and that their EPR line widths vary with the pore diameters and the surface areas of the zeolites. The spectra of VO(H2O)5
2+ in natural zeolites at room temperature display an isotropic behavior and therefore indicate that the water ligands are mobile. The EPR spin Hamiltonian parameters, the molecule orbital constant ß2
*2 , and the Fermi contact term Keff were determined and are discussed. The spectra of Mn(H2O)6
2+ for narrow-pore zeolites indicate the existence of mobile and immobile water, whereas for wide-pore and natural zeolites they indicated the existence of only mobile water. The obtained Mn(H2O)6
2+ spectra are discussed.
Intensities and Widths of the Rovibrational Lines Observed in the 2ν5 Overtone Band of Cyanoacetylene
Authors: Yamada K.M.T. , Moravec A. , Niedenhoff M. , Winnewisser G. 
Published: February 2015

Abstract
The relative intensities and Lorentz half-widths of rovibrational transitions observed for the 2ν5 overtone band of cyanoacetylene, HCCCN, have been determined. The line widths and the intensities were obtained by fitting the observed line profiles with Voigt functions. The Lorentz half-width shows a clear J dependence and vanishes at J ~ 100. In the intensity calculation, we took into account the effects of the accidental resonances between the ν5 = 2 state and the (ν4 = 1, ν7 = 2) state as well as those of the generic l-type resonance. Peak intensities have been found not to be the appropriate presentation of the line intensity because of the strong J dependence of the half-width.
Distortion of the Benzene Ring in 1,2,3-Trifluorobenzene; A High-Resolution Molecular Beam Fourier Transform Microwave Study
Authors: Wolschendorf Ulrich , Kretschmer Uwe , Sutter Dieter H. 
Published: February 2015

Abstract
The results of a molecular beam microwave Fourier transform study of 1,2,3-trifluorobenzene and its monosubstituted 13C-isotopomers, all observed in natural abundance, are presented. Typically 30 transitions were observed for each isotopomer. Centrifugal perturbation theory up to fourth order was used to analyse the observed rotational spectra. Due to the high sensitivity and resolution of the spectrometer, very accurate vibronic ground state rotational constants can be reported:

They are used to derive a partial r0-structure. which shows the distortions of the benzene ring caused by fluorine substitution.
The Structure of Zinc Chloride Complexes in Aqueous Solution
Authors: Maeda M. , Ito T. , Hori M. , Johansson G. 
Published: February 2015

Abstract
The structure of zinc chloride complexes with different ratios of chloride to zinc, formed in concentrated ZnCl2 aqueous solutions, were determined from large-angle X-ray scattering using concentrations of the chloride complexes estimated by complementary Raman spectroscopic measurements. The highest chloro complex, [ZnCl4]2-, is tetrahedral with a Zn-Cl bond length of 2.294(4) Å. The trichloro complex, [ZnCl3]-, which coordinates one water molecule, is pyramidal with the Cl-Zn-Cl angle 111°. The Zn-Cl and the Zn-H2O bonds are 2.282(4) and 1.9 Å, respectively. The two lower complexes, [ZnCl2] and [ZnCl]+ , cannot be separated by Raman spectra. The average Zn-Cl distance in these complexes is 2.24 Å, and the average Zn-H2O distance is 1.9 Å. In [Zn(H2O)6]2+ the Zn-H2O distance is 2.15 Å.
Self-Diffusion in the Ionic Plastic Phase of (CH3 )3 NHClO4 Studied by 1H NMR and Electrical Conductivity
Authors: Ishida Hiroyuki , Furukawa Yoshihiro 
Published: February 2015

Abstract
Spin-lattice relaxation times (T1) and spin-spin relaxation times (T2) of 1H NMR and the electrical conductivity (σ) of trimethylammonium perchlorate were measured in the ionic plastic phase obtainable above 480 K. In this phase, both the cation and anion were revealed to perform self-diffusion. The activation energy (Ea ) of the cationic diffusion was evaluated to be 55 ± 4 and 50 ± 4 kJ mol-1 from 1H T1 and 1H T2 respectively, while Ea of the anionic diffusion was 64 ±3 kJ mol-1 from the electrical conductivity.
Description of the Glass Transition by a Percolation Blocking of Local Chemical Order
Authors: Blétry J. 
Published: February 2015

Abstract
A model for the liquid-glass transition, based on a percolation blocking of local chemical order, is proposed. The case of metallic liquids and glasses, whose structure is dominated by first neighbour chemical arrangement, is first treated. The chemical ordering "reaction" of the liquid phase is studied at thermodynamical equilibrium and the increase of the chemical order parameter with decreasing temperature is calculated. Within a given composition interval, however, a geometrical percolation process is shown to block this reaction below a "percolation temperature" (corresponding to null cooling rate) where the liquid is irreversibly frozen into a glass. The liquid-glass "phase diagram" is established and kinetic arguments, involving "frustrated" finite clusters which are formed close to the percolation threshold, provide an evaluation of the experimentally measured "glass transition temperature" as a function of cooling rate. The validity of this one order parameter model is then discussed with the help of the irreversible thermodynamics theory of Prigogine.
The formation of tetracoordinated glasses is explained by the formation of tetrahedral bonds, when the liquid temperature decreases, and represented by a "hole ordering" reaction. A general description of the structure of tetracoordinated glasses is thus achieved, which applies to amorphous silicon and germanium, 111 -V compounds, silica, amorphous water etc. Furthermore, an estimation of the temperature interval for the glass transformation of silica is obtained, which agrees well with experiment.
The existence of frustrated clusters gives to glasses a composite structure in the "medium distance order", which could explain the "fractal nature" of glass fracture surfaces down to the nanometer scale.
The Mercury-Sensitized Photolysis of Pentamethyldisilane
Authors: Kerst C. , Potzinger P. , Wagner H. Gg. 
Published: February 2015

Abstract
Two primary processes were observed in the Hg-sensitized photolysis of Me 5 Si 2 H: (I) hydrogen abstraction from the Si-H bond with a quantum yield of 0(1) = 0.85, (V) Si-Si bond breaking with 0(V) = 0.04. The hydrogen atoms formed in (/) undergo an H atom abstraction reaction (k(3)), as well as substitution reactions at the Si centers resulting in the formation of dimethylsilane and trimethylsilyl radical (k(4)) or trimethylsilane and dimethylsilyl radical (k(5)). The following branching ratios have been determined:
[xxx]
The ratio of disproportionation (k(2)) to combination (k(1)) for the pentamethyldisilyl radical has been determined with MeOH as the scavenger for 1-methyl-l-trimethylsilylsilene, 0.046 < k(2)/
A: C1) < 0.071. A mechanism with pertinent rate constants has been proposed which accounts for the
results.
Terahertz Spectrum of Trioxane
Authors: Klein H. , Belov S. P. , Winnewisser G. 
Published: February 2015

Abstract
The pure rotational spectrum of trioxane, (H2CO)3 the trimer of formaldehyde, has been recorded with high resolution in the frequency range between 326 and 947 GHz for the main isotopomer, the 13 C, and the 18O isotopic species in the vibrational ground state. These new high J and K data reveal that the molecule is fairly rigid. For the constants determinable from the recorded high J and K spectra (J = 90 and K = 75) the rotational constant
B = 5273.257 180(33) MHz,
the two quartic centrifugal distortion constants DJ, and DJK, and the three sextic constants HJ, HJK, and HKJ are needed in the fit to reproduce the measured spectra within experimental accuracy. In addition, for the 13C isotopomer the sextic constants HJK and HKJ are determined as well as the off-diagonal parameters d1 and d2.
The Rotational Spectrum and Nuclear Quadrupole Coupling of CH35C1F2
Authors: Blanco Susana , Lesarri Alberto , López Juan C. , Alonso José L. , Guarnieri Antonio 
Published: February 2015

Abstract
The rotational spectrum of CH35CIF2 in the ground vibrational state has been measured in the frequency range 8-18 GHz using a waveguide Fourier transform microwave (FTMW) spectrometer in order to determine accurate nuclear quadrupole coupling constants. The spectra of the excited vibrational states ν5 = 1, ν6 = 1 and ν9 = 1 have been also observed and analyzed in the frequency region 8-250 GHz using FTMW, Stark, and source modulation spectrometers. Quadrupole coupling constants are also reported for these states.
Resolution of constraints and gauge equivalence in algebraic Schrödinger representation of quantum electrodynamics
Authors: Stumpf H. , Pfister W. 
Published: February 2015

Abstract
The algebraic formalism of QED is expounded in order to demonstrate both the resolution of constraints and to verify gauge equivalence between temporal gauge and Coulomb gauge on the quantum level. In the algebraic approach energy eigenstates of QED in temporal gauge are represented in an algebraic GNS basis. The corresponding Hilbert space is mapped into a functional space of generating functional states. The image of the QED-Heisenberg dynamics becomes a functional energy equation for these states. In the same manner the Gauß constraint is mapped into functional space. By suitable transformations the functional image of the Coulomb forces is recovered in temporal gauge. The equivalence of this result with the functional version of QED in Coulomb gauge is demonstrated. The meaning of the various transformations and their relations are illustrated for the case of harmonic oscillators. If applied to QCD this method allows an exact derivation of effective color "Coulomb" forces, in addition it implies a clear conception for the incorporation of various algebraic representations into the formal Heisenberg dynamics and establishes the algebraic "Schrödinger" equation for quantum fields in functional space.
Novel Formulation of the Gibbs–Energy Change in Terms of Stoichiometrically Unique Response Reactions
Authors: Fishtik Ilie , Nagypál István , Gutman Ivan 
Published: February 2015

Abstract
The equation for the change of Gibbs energy in complex chemical systems is reformulated in terms of the newly conceived response reactions (RERs). The present formulation has the remarkable property of being unique: the composition of the species unequivocally determines the response reactions and via them the change of the Gibbs energy of the system. Furthermore, it enables one to reinterpret and rationalize some basic concepts of chemical thermodynamics, as coupling between reactions, sensitivity coefficients, etc.