bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the Liquid Crystalline Phases in Some Compounds of 4-Trans-(4-Alkyl)Cyclo-Hexylphenyl-Alkylcarboxylate
Authors: Ibrahim I. H. , Haase W. 
Published: February 2015

Abstract
Three mesogenic compounds of the general formula

have been investigated by differential scanning calorimetry. thermal optical microscopy and X-ray diffraction methods/Enthalpy changes of The different phase transitions for these compounds have been determined. H33 exhibits smectic B and nematic phases, whereas H34 and H75 exhibit only smectic B phases. The thickness of the smectic layers and the average intermolecular distance have been evaluated, as well as the corresponding molecular parameters in the nematic phase.
Zur Interpretation des Substituenteneinflusses auf das UV-spektroskopische Verhalten von Benzimidazol- und Indazolderivaten
Authors: Fabian Walter 
Published: February 2015

Abstract
On the interpretation of the influence of substituents on the UV-spectroscopic properties of benzimidazole and indazole derivatives.
The UV spectra of a series of substituted benzimidazoles and indazoles were calculated by means of semiempirical quantum chemical methods (PPP, CNDO/S-CI). The results of the PPP calculations were subjected to a configuration analysis. Using this method, the influence of the nature and position of substituents on the absorption characteristics could be rationalized.
Thermal Expansion of Lithium Sulphate
Authors: Meilander B. E. , Nilsson L. 
Published: February 2015

Abstract
The thermal expansion of the α and β phases of lithium sulphate has been studied using dilatometric and X-ray diffraction techniques. In the α-phase the coefficient of linear thermal expansion is 4.6·10-5 K-1 while in the β-phase the coefficient of linear thermal expansion increases from 0.9·10-5K-1 at room temperature up to 3.4·10-5 K-1 close to the first order phase transition at 575 °C. The volume expansion at the phase transition is 3.2%. In the α-phase the thermal Grüneisen parameter has been calculated to be 0.63 at 705 °C.
Protonation of 4 H-Pyran-4-one and its Sulfur Analogues. MNDO Study
Authors: Eckert-Maksić Mirjana 
Published: February 2015

Abstract
The molecular and electronic structure of 4H-pyran-4-one and its mono- and disubstituted sulfur analogues (1-4) are studied by the MNDO method. The salient structural features are qualitatively reproduced and the trend of changes of geometric parameters is in good agreement with experiment. The charge distributions exhibit strong polarization due to the large π-electron drift toward the exo-heteroatom. The protonated conjugated acids are considered too. It is found that exo-heteroatom protonation is favoured by 60-80 kcal/mol over the attachment of the proton to the intraring heteroatom. This is in accordance with experimental evidence. It is rationalized by the higher electron density centered on the exo-heteroatom and the appreciable increase in aromatic cyclic conjugation taking place upon the exo-protonation.
Molar Heat Capacity of AgI: Evaluation of the Cationic and Anionic Contributions from Thermoelectric Power Data
Authors: Schiraldi Alberto , Baldini Primo 
Published: February 2015

Thermoelectric power data provide a useful tool for the evaluation of the thermodynamic properties of ionic species of both solid and molten electrolytes in equilibrium with electrodes of thermocells; however a previous evaluation of the heat of transport of the mobile ions is necessary.
This is the case of AgI. whose standard modifications have been investigated with silver electrode thermocells some years ago. The interpretation of the thermoelectric power change at the melting point allows one to recognize that the heat of transport of the silver ions in the high conductivity bcc modification is practically the same as in molten Agl. This result has been used to evaluate the molar heat of the silver ions in the bcc phase from the corresponding thermoelectric power data reported in the literature.
The analysis of the thermoelectric power change at the transition point, from the wurtzitic to the bcc phase, as well as a more speculative interpretation of thermoelectric power data obtained with iodine electrode thermocells, allows one to evaluate the molar heat of the iodide ions in the bcc modification of AgI.
The summation of the ionic contributions so computed reproduces rather satisfactorily the trend of AgI molar heat data obtained with adiabatic calorimetry.
Relativistische Verallgemeinerung des Lenzschen Vektors (II) / Relativistic generalisation of the Lenz vector (II)
Authors: Kern Eberhard 
Published: February 2015

The Lenz vector Λ= m {x′ × L + α · x/r} is a special integral of motion of the non-relativistic Kepler problem. Accordingly, there also exists a special integral of motion Λ (x, x') of the relativistic Kepler problem as pointed out in Part I of this paper. In the following Part II, the system of equations is compiled to the extent required for the relativistic generalisation of the Lenz vector and its interpretation.
Starting point are the statements of conservation for the energy and the angular momentum. From these two quantities, it is possible to derive the complete system of solutions x(t) in accordance with standardised methods. Some details and some modifications of the approach are of special importance for the purposes of this paper. In the centre of the consideration are the construction and interpretation of the standardised polar angle θ as a function of r, r'. The explicit time dependance of the functions r(t), θ(t) is not required for constructing the relativistic Lenz vector in the form Λ (x, x').
In the literature, one does Find only few, not sufficient for our purposes, data on the relativistic orbits (rosettes, spirals, hyperbola-type curves etc.). It is, therefore, necessary to discuss these orbits in detail. For this purpose, a series of relationships are derived which apparantly have not been published before.
Rayleigh-Taylor Instability of a Stratified Magnetized Medium in the Presence of Suspended Particles
Authors: Chhajlani R. K. , Sanghvi R. K. , Purohit P. 
Published: February 2015

Abstract
The hydromagnetric Rayleigh-Taylor instability of a composite medium has been studied in the presence of suspended particles for an exponentially varying density distribution. The prevalent horizontal magnetic field and viscosity of the medium are assumed to be variable. The dispersion relation is derived for such a medium. It is found that the stability criterion is independent of both viscosity and suspended particles. The system can be stabilized for an appropriate value of the magnetic field. It is found that the suspended particles can suppress as well as enhance the growth rate of the instability in certain regions. The growth rates are obtained for a viscid medium with the inclusion of suspended particles and without it. It has been shown analytically that the growth rate is modified by the inclusion of the relaxation frequency parameter of the suspended particles.
Luminescence of 5-Phenyltetrazole and its Derivatives Part III. Quantum Yields and Mean Lifetimes of Fluorescence
Authors: Gryczyński I. , Kawski A. 
Published: February 2015

Abstract
Quantum yields and mean lifetimes of fluorescence have been measured of 5-phenyltetrazole and its three methyl derivatives, para-, meta- and ortho-methyl-5-phenyltetrazole. The rate constants, kF, of the radiative transition S1 → S0 have been deduced from these measurements. The mean lifetimes, τF, the quantum yields of fluorescence and the rate constants have been found to be clearly dependent on the position of the methyl substituent in the ring and could be arranged as follows:
τp
F>τm
F>τ0
F and k0
F>km
F>kp
F
Dolomite Decomposition to (Ca,Mg)O Solid Solutions: An X-Ray Diffraction Study, Part I.
Authors: Spinolo G. , Tamburini U. Anselmi 
Published: February 2015

Abstract
Dolomite [CaMg(CO3)2] full decomposition has been studied by in situ powder X-ray diffraction. The primary products are Ca-rich and Mg-rich (Ca.Mg)O solid solutions with compositions different from equilibrium values. In some cases a strained form of calcite is also produced. The experimental results show that the oxides are formed in a direct process with a shear mechanism, whereas calcite formation is due to CaO recarbonation.
Carboxylic Acid-N Base Hydrogen Bonds with Large Proton Polarizability in Acetonitrile as a Function of the Basicity of the Hydrogen Bond Acceptors
Authors: Albrecht Gunnar , Zundel Georg 
Published: February 2015

Abstract
Carboxylic acid-N base systems are studied in acetonitrile. The association equilibrium constants Ka and the proton transfer equilibrium constants KPT in the OH···N ⇄ O-···H+N bonds formed, are determined from IR spectra. The association constants Ka increase in proportion to the basicity of the hydrogen bond acceptors. The same is true with regard to the proton transfer constants. The OH ···N ⇄ O- ···H+N equilibria are shifted with increasing basicity to the right hand side. It is discussed that this shift is caused by an intrinsic effect as well as by an extrinsic one (interaction of the dipole of the hydrogen bond with its environment). A linear relation exists between log KPT and ⊿pKa (pKa of the protonated base minus pKa of the acid). 50% transfer of the protons to the N base is found at ⊿pKa = 2.6. As indicated by intense continua. these hydrogen bonds show large proton polarizability if the degree of asymmetry of their proton potentials is not too large.
On the Infrared A2Πi - X2∑+ System of Aluminium Monoxide in Relation with the Spectra of M Giant- and Mira-Type Stars
Authors: Bernard A. , Gravina R. 
Published: February 2015

From combinations between known ultraviolet transitions of the AlO molecule line positions in the A2Πi - X2∑+ system are tentatively proposed. Indeed, the available data on the C2Πr → X2∑+ and C2Πr → A2Πi transitions permit us to derive about 2400 energy level differences in the A-X system corresponding to the six ν-connected bands 0-0, 0-1, 0-2, 1-0, 1-1 and 1-2. A unique and consistent set of rovibrational constants is derived from a global fitting, allowing to reproduce the observed differences with a total standard deviation of 0.053 cm-1. A catalogue of vacuum line wavenumbers in the six bands is generated and can be made available on request. The synthetic spectra are expected to represent properly the true spectra at least up to J ~ 35.5 and can therefore be of usefulness for the detection of the system in the spectra of M giant- and Mira-type stars.
Franck-Condon factors and r-centroïds appropriate to RKR potentials and estimates of intensities in emission are given for bands up to ν′ = 5, v″ = 8.
More reliable values for the internal partition functions and dissociation constants of AlO are computed for temperatures between 1000 and 8000 K. All the known and predicted electronic states are taken into account, and present or recent values for the molecular parameters and dissociation energy are used.
Pattern of Intrinsic Reaction Coordinates and Separatrices for a Symmetry-Forbidden Reaction
Authors: Fernández Ariel 
Published: February 2015

The relative distribution of the basins of attraction of the chemical species and of the transition states is derived for the thermal isomerization of cyclobutene to butadiene.
It is shown that the transition states for the symmetry-allowed and symmetry-forbidden pathways are lumomers of one another. Use is made of the structural stability principle of Ariel Fernández and Oktay Sinanoglu to show that these transition states are respectively the conrotatory and disrotatory Jahn-Teller distortions of the 2-butene diradical.
The results exhibit good agreement with J. A. Berson’s conclusions in the sense that even the forbidden pathway is concerted.
The Influence of the Cell Geometry on the Signal Shape in Electron Drift Velocity Measurements
Authors: Borghesani A. F. , Bruschi L. , Santini M. , Torzo G. 
Published: February 2015

An accurate determination of the “time-of-flight” in swarm experiments with a parallel plate drift chamber requires that the time evolution of the charge induced on the collector is linear. This is obtained in very large chambers where the edge effects can be neglected. However, the experimental conditions of high-mobility carriers and highly pressurized gases impose some constraints on the acceptable drift cell dimensions. We have numerically calculated the effects of the finite size of the collector by exploiting the methods of the images. The numerical results have been experimentally checked using a suitable drift cell of variable geometry. As a result, a quantitative limit on the ratio between the collector radius and the drift distance has been established in order to design drift cells for which the edge effects can be neglected.
P.A.C.S. numbers: 2940. 4110 D, 3480 B
Pressure and Temperature Dependence of Self-Diffusion in Liquid Linear Hydrocarbons
Authors: Bachl F. , Lüdemann H.-D. 
Published: February 2015

The pressure and temperature dependence o f the self-diffusion coefficients D of n-butane, n-pentane, n-hexane, n-decane, trans-2-butene, cis-2-butene and 2-butyne were determined in the liquid state by NM R-techniques at pressure up to 200 MPa and temperatures up to 450 K.
The results are taken as tests for the various dynamical models and compared to results obtained by M D calculations. The activation parameters for translational transport and the parameters for the RHS-m odel are derived and discussed.
Notizen: A Highly Resolved Rotational Transition of Urea Measured for Radioastronomical Searches. Analysis of the Nitrogen Quadrupole Coupling
Authors: Kasten W. , Dreizler H. 
Published: February 2015

We reinvestigated the 14N quadrupole hyperfine structure (hfs) of the JK-K+ = 110 - 101, transition of urea by use of microwave Fourier transform spectroscopy.
We resolved eight components of the hfs pattern to provide a precise laboratory experiment for possible radioastronomical searches.
Temperature Dependence of the 127I Quadrupole Coupling in Periodates with Alkyl- or Aryl-Substituted Cations of Main Group V
Authors: Klobasa Dagmar G. , Burkert Paul K. , Müller Gerhard 
Published: February 2015

127I solid state NMR studies of metaperiodates with alkyl- or aryl-substituted cations of main group V revealed second order quadrupole effects with quadrupole coupling constants in the range of 2 - 7 MHz.
In (C2H5)4PIO4 and (C2H5)4AsIO4 the 127I quadrupole coupling constants show normal temperature coefficients ᾱ in the order of -10-4 K-1 for 186 K < T < 300 K.
For the metaperiodates with aryl-substituted cations (C6H5)4P+, (C6H5)4As+ and (C6H5)4Sb+ complicated temperature dependences of the 127I quadrupole interaction with phase transitions and anomalous positive temperature coefficients +0.2 · 10-2K-1 ≦ ᾱ ≦ +0.8 · 10-2K-1 were observed.
The relevance of possible mechanisms for the anomalous temperature coefficients, like breakdown of dη - pη backbonding, negative pressure coefficients, charge transfer, orientational change of the EFG-tensor axes system and influence of reorientational motions is discussed for these compounds, including results from an X-ray investigation of (C6H5)4AsIO4 and 1H-solid state NMR measurements.
Deuterium Quadrupolar Parameters from 1H and 2H NMR Spectra for Pyridine-d5, Benzonitrile-d5 and Chlorobenzene-d5 Using Liquid Crystal Solvents
Authors: Ambrosetti R. , Catalano D. , Forte C. , Veracini C. A. 
Published: February 2015

T he quadrupolar coupling constants (DQCC) and the asymmetry parameters (η) for the ortho, meta and para deuterons in pyridine-d5, benzonitrile-d5 and chlorobenzene-d5 were determined by NMR spectroscopy in oriented phases. The 1H and 2H NMR spectra were recorded in the following solutions in liquid crystal solvents: pyridine + pyridine-d5 in PCH , in ZLI 1167 and in EBBA; benzonitrile + benzonitrile-d5 and chlorobenzene + chlorobenzene-d5 in the same solvents.
The order parameters of the non-deuterated solutes in the various solutions were calculated using the dipolar couplings of the proton spectra and the rα structures taken from the literature. The same order parameters were assumed to describe also the orientation of the deuterated solute in the corresponding solutions.
Each 2H spectrum yielded three quadrupolar splittings for the three different deuterated positions in the labelled solute. The splittings from the three different solutions of the same solute, together with the order parameters and the rα structure, were used to determine DQCC and η of the ortho, meta and para deuterons (Pyridine-d5: DQCCortho= 183(1) kHz, ηortho = 0.030(5), DQCCmeta = 185(1) kHz, ηmeta = 0.030(10), DQCCpara = 188(6) kHz, ηpara = 0.01(5). Benzonitrile-d5: DQCCortho = 171(12) kHz, ηortho = 0.07(3), DQCCmeta = 175(12) kHz, ηmeta = 0.05(3), DQCCpara = 176(4) kHz, ηpara = 0.10(7). Chlorobenzene-d5: DQCCortho = 180(2) kHz, ηortho = 0.06(1), DQCCmeta = 174(2) kHz, ηmeta = 0.09(3), DQCCpara= 182(4) kHz, ηPara = 0.06(4)). The results are discussed, as well as the limits and possibilities of the method used.
The Rotational Zeeman Effect of Pyrazole and Imidazole
Authors: Stolze M. , Sutter D. H. 
Published: February 2015

The rotational Zeeman effect of the most abundant isotopic species of pyrazole and of imidazole has been studied under Δ M= 0 and Δ M = ± 1 selection rules. With field close to 1.9 Tesla, the nuclear Zeeman effect uncouples the rotational angular momentum and the spins of the two nonequivalent 14N quadrupole nuclei. The observed g-tensor elements are gaa = - 0.07498(14), gbb = - 0.12531(13), and gcc = 0.06346(12) for pyrazole and gaa = - 0.09339(16), gbb = - 0.10444(14), and gcc= 0.06051(15) for imidazole. The values for the magnetic susceptibility anisotropies in units of 10-6 erg/(G2 mol) are 2Xaa - Xbb - Xcc = 39.53(24) and 2Xbb - Xcc - Xaa = 51.20(21) for pyrazole and 2xaa - Xbb - Xcc = 45.76(31) and 2Xbb - Xcc - Xaa = 42.19(41) for imidazole. (Given uncertainties are single standard deviations of the fit.)
The so-called nonlocal (π-ring current) contributions to the out of plane components of the susceptibility tensor Xcc
nonlocal, derived as differences between the observed susceptibilities and values calculated from additivity rules for local atom susceptibilities, are compared to those derived earlier for other aromatic five membered ring molecules.
General Relations between Molecular Sensitivities and Their Physical Content
Authors: Nalewajski Roman F. 
Published: February 2015

Abstract
The molecular Legendre transformed representations are reexamined. They correspond to alter­native sets of parameters defining the constraints imposed on the system. In the global description the molecular (equilibrium) states are defined by the global state parameter G = (N or μ) and the state function f (r) = [υ(r) or n(r)]; N is the system number of electrons, μ its chemical potential, υ stands for the external potential due to the nuclei, and n is the electron density. In the local description, capable of defining non-equilibrium molecular density distributions, the state is defined by two state functions, g(r) = [n(r) or μ (r)] and f (r); here μ (r) is the local chemical potential of the electron distribution in small volume element around r. The Maxwell cross differentiation identities in both approaches, relating various molecular sensitivities, are physically interpreted. A qualitative discussion of general relations between molecular sensitivities is given and their physical content and possible applications are commented upon.
The Infrared, Raman, and Vibronic Spectra of Europium Chelates
Authors: Zachara S. , Szyncel M. 
Published: February 2015

Absorption spectra in the far and intermediate infrared, as well as Raman and vibronic spectra were measured for three crystalline forms of four-ligand europium chelate with dibenzoylmethane and piperidine and a three-ligand chelate in the spectral ranges: 40-450, 450-4500, 0-4500 and 0-1600 cm - 1 , respectively.
The analysis of the individual spectra enabled the identification of the frequencies corresponding to the vibrations of the Eu -O bond coupled with the lattice vibrations, and the frequencies of the intraligand vibrations. It is found that piperidine is bound to the complex molecule by hydrogen bond.
Anomalous X-ray Scattering Study of GeO2Glass
Authors: Matsubara E. , Harada K. , Waseda Y. , Iwase M. 
Published: February 2015

Abstract
The anomalous X-ray scattering (AXS) technique was applied to a structural study of GeO2 glass, using synchrotron radiation and a new goniometer system. The environmental radial distribution function (RDF) was determined from intensity measurements at the Ge K absorption edge and compared with the ordinary RDF curve estimated from the. X-ray scattering intensity by Mo K α radiation. By combining the environmental and ordinary RDFs of the GeO2 glass it has been confirmed that the fundamental local unit structure is a GeO4 tetrahedron and that these tetrahedra are joined at their corners to form a network structure. The capability of the AXS technique has been approved as a relatively new tool for the structural characterization of disordered materials.
Photoinduced Transformation of Carbon Monoxide in Aqueous Solution
Authors: Park Hyoung Ryun , Getoff Nikola 
Published: February 2015

Abstract
The photoinduced conversion of CO in aqueous solution under the influence of vacuum-uv radiation at λ = 185 nm has been investigated at pH values ranging from 2 to 13. Formaldehyde, glyoxal, carboxylic acids and small amounts of glycol were determined as final products. Initial quantum yields for product formation have been determined. A probable reaction mechanism is presented.
Structural Phase Transitions in Solid tert-Butylammonium Nitrate as Studied by Differential Thermal Analysis and 1H-NMR
Authors: Ishida Hiroyuki , Iwachido Tadashi , Hayama Naomi , Ikeda Ryuichi , Hashimoto Miyuki , Nakamura Daiyu 
Published: February 2015

Abstract
Seven solid phases including three metastable phases of (CH3)3CNH3NO3 were revealed by differential thermal analysis in the temperature range between 80 K and the melting point (418 K), and cationic dynamics in each phase was studied by use of 1H-NMR techniques. The highesttemperature solid phase obtainable above 412 K was found to be an ionic plastic phase, where the cations perform rapid translational self-diffusion and overall rotation about their center of gravity.
A Model Study of Instabilities Present in the Mean-Field Description and in Linearized Correlation Schemes
Authors: Böhm Michael C. , Bubeck Gerd , Oles Andrzej M. 
Published: February 2015

Abstract
In this work we discuss the cooperative occurrence of instabilities in the Hartree-Fock (HF) approximation and linearized correlation models. Both breakdown phenomena can be analyzed via eigenvalues of characteristic matrices. The well known HF instabilities follow from a quasidegeneracy between the symmetry-adapted mean-field state and singly excited configurations. Quasi-degeneracies between the HF wave function and doubly excited configurations restrict the applicability of linearized correlation models. In the theoretical calculations the method of the local approach (LA) has been employed to derive the correlated ground state. For a system of the general topology XH2 (X = C, Si, etc.) the bond orbital approximation (BOA) has been used to derive analytic formulae indicating the stability range of linearized correlation schemes. Numerical calculations on the basis of a simple model-Hamiltonian are given for the π systems C2H4 and C2H2, respectively, which have been studied as a function of the CC bondlength. The comparison of the respective numerical data indicates that both breakdown phenomena are enhanced via coupling terms between strongly correlated bonds.