bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Range of the Wiener Index and Its Mean Isomer Degeneracy
Authors: Gutman I. , Šoltés L. 
Published: February 2015

Abstract
Sharp lower and upper bounds for the Wiener index (W) of a connected (n, m)-graph are reported; n = number of vertices, m = number of edges. The mean isomer degeneracy of W is estimated and is shown to unboundedly increase with increasing n. Thus the isomer-discriminating power of W is confirmed to be very low in the case of large molecules.
Dielectric Relaxation Spectroscopy of Electrolyte Solutions: ZnCl2 in N-Methyl-2-pyrrolidone
Authors: Brockmann  , Steffen A. , Stockhausen M. 
Published: February 2015

Abstract
The complex permittivity of the title solution system (c≤1.5 mol/1) was measured at frequencies ranging up to 72 GHz at 20 °C. Apart from the conductivity contribution there are two distinguishable relaxation regions, which are ascribed to the solvent (at higher frequencies) and to solvated ionic species (at lower frequencies).
Notizen: Fluoreszenzlöschung von protonierten Aza-arenen durch äußere Schweratomstörer (Methyliodid und Silberperchlorat)
Authors: Zander M. 
Published: February 2015

Abstract
In contrast to arenes, the fluorescence of protonated azaarenes in fluid solution is more readily quenched by methyl iodide than by silver Perchlorate. This is probably due to the Coulomb repulsion between the fluorescent ion and the silver ion, thus inhibiting the formation of a non-fluorescent complex.
109Ag and 29Si NMR Investigations of Scalar Couplings and Relaxation on Cyclo-tetrakis[tri-tert-butoxysilanethiolatosiIver(I)],[(t-C4H9O)3SiSAg]4
Authors: Schwenk A. , Piantini U. , Wojnowski W. 
Published: February 2015

Abstract
From the 29Si NMR spectrum of [(t-BuO)3SiSAg]4 with a partly resolved fine structure recorded at 9.4 T, the coupling constants |J(29Si,109Ag)| = (4.49 ±0.04) Hz and | J(29Si, 107Ag)| = (3.90 + 0.03) Hz were derived. The 109Ag spectra at 9.4 T and at 2.1 T are single lines without fine structure shifted to higher frequency by δ = (725.8 ± 1.5) ppm relative to the resonance of the Ag + ion in aqueous solution at infinite dilution. No hint of any {Ag, Ag}-coupling can be derived from these spectra and from a comparison of the FID- and steady-state-signal intensities, i.e. | J (Ag, Ag) | < 1 Hz. This result is in contrast to the assumption of an Ag-Ag bond to explain the spatial shift of the Ag atoms towards the centre of the alternating Ag4S4-eight-membered central ring of the molecule. For the first time silver relaxation was investigated in a molecule. T1(109Ag) was determined at 9.4 T and at 2.1 T and at different temperatures to separate the contributions of different mechanisms: chemical shift anisotropy is the dominating one. T1=20.2 s at 2.1 T and at 301 K in this molecule is shorter by nearly two orders of magnitude than T1 of the Ag+ ion in aqueous solution
Self-Organized Critical Dynamics and Phase Transition Behavior During Avalanche Breakdown in p-Germanium
Authors: Knoop M. , Parisi J. , Clauß W. , Rau U. , Peinke J. 
Published: February 2015

Abstract
We give experimental evidence that self-organized criticality takes place during the formation of low-temperature semiconductor breakdown. Quantitative evaluation of the characteristic scaling properties together with the appropriate parameter ranges of validity further support the applicability of the model conjectured
Some Aspects of Minimally Relativistic Newtonian Gravity
Authors: Nandi Kamal K. 
Published: February 2015

Abstract
This paper aims to examine if the classical tests of General Relativity (GR) can be predicted by a simpler approach based on minimal changes in the Newtonian gravity. The approach yields a precession of the perihelion of Mercury by an amount 39.4"/century which is very close to the observed Dicke-Goldenberg value (39.6"/century), but less than the popularly accepted value (43"/ century). The other tests exactly coincide with those of GR. Our analysis also displays the genesis as well as the role of geometry in the description of gravitational processes. The time dependent spherically symmetric equations, which are mathematically interesting, call for a further study. The model also allows unambiguous formulation of conservation laws. On the whole, the paper illustrates the limited extent to which a second rank tensor analogy (nonlinear) with flat background Faraday-Maxwell electrodynamics can be pushed in describing gravitation
Lattice Vibration Spectra. LXX. Evaluation of IR Reflection Spectra. Model Calculations and Experimental Data of MnCr2O4 Single Crystals
Authors: Himmrich J. , Schneider G. , Zwinscher J. , Lutz H. D. 
Published: February 2015

Abstract
The various evaluation procedures of IR reflection spectra, viz. Kramer-Kronig analyses (KKA), 3 parameter (coTO, g, y) (3 PM), and 4 parameter (ωro, ωLO yro yLO) oscillator-model calculations (4 PM), are compared. For the zone-centre phonon energies, the oscillator parameters ωro and ωLO of 4 PM as well as the frequencies of the dielectric functions ε" and - Im(l/ε), respectively (KKA, 3 PM), are recommended. The pole frequencies of the |ε| functions yield too large TO/LO splittings, especially in the case of large damping of the phonons. In the case of asymmetric reststrahlen bands, the use of 4 PM with different damping constants y for the TO and LO phonons is recommended. Computer simulations of the influence of the various oscillator parameters on the reflection spectra as well as the phonon frequencies of spinel-type MnCr2O4 are included
X-ray Emission Wavelengths of Argon, Krypton, Xenon, and Curium
Authors: Kleykamp H. 
Published: February 2015

Abstract
The wavelengths of the L series of argon, krypton and xenon, the K series of argon, and the M series of curium were measured by means of wavelength dispersive X-ray microanalysis. The specimens for the investigations were TiC layers which had been HF sputtered under reduced argon pressure by the PVD method, krypton and xenon implanted zeolites, and a curium doped borosilicate glass. The obtained relative intensities of the X-ray emission lines were normalized to the maximum intensity of the line of the respective series
The Role of Singlet Oxygen in the Lyoluminescence of Saccharides
Authors: Pitt E. , Scharmann A. , Suprihadi T. 
Published: February 2015

Abstract
Lyoluminescence, the radiation induced light emission during the dissolution of irradiated solid substances like alkali halides, saccharides, amino acids etc. was proposed as a method of dosimetry. It is established that lyoluminescence is a consequence of a reaction of radicals from radiolysis with oxygen dissolved in the solvent. The role of oxygen in the lyoluminescence of saccharides has been investigated. It has been proved that oxygen is not only necessary for the chemical reaction preceeding the lyoluminescence process, but that it is also the emission centre itself. Singlet oxygen is released from the disproportionation of peroxyl radicals produced during solution. The lyoluminescence emission peaks may be attributed to the simultaneous transitions [ 1Σ g
+ ] [ 1Σ g
+ ] , [ 1Δg ] [1 Δg ] and [1Σg
+] [ 1Δg ] to [3Σg
+] [3Σg
-] of collisional pairs of singlet oxygen molecules
The Effect of Temperature on the Fluorescence Quenching of Perylene by Tetrachloromethane in Mixtures with Cyclohexane and Benzene
Authors: Wiczk Wieslaw M. , Latowski Tadeusz 
Published: February 2015

Abstract
The effect of temperature on the fluorescence quenching of perylene has been studied in a variety of two-component mixtures of CCl4 with cyclohexane and benzene. Results of these studies are explained in terms of specific interactions between the components of the mixtures
On the Problem of a Finitistic Quantum Field Theory
Authors: Winterberg F. 
Published: February 2015

Abstract
A finitistic quantum field theory, as a model for a unified theory of elementary particles is proposed, making the assumption that all spatial and temporal distances can only assume integer values of a fundamental length and time, for which we have chosen the Planck length and Planck time. To satisfy the condition of causality in its quantized version, the theory must be exactly nonrelativistic, because only then can the concept that points in space are separated by multiples of a fundamental length be formulated in an invariant way. The theory is formulated as a partial finite difference equation, invariant under translations and rotations in space, and translations in time, and can be expressed as a partial differential equation of infinite order. The theory is free of all divergencies, has a positive definite metric in Hilbert space and therefore no ghost states. Possessing a fundamental length, chosen to be equal the Planck length, the theory has an inbuilt cut-off at the Planck energy. For energies sufficiently below the Planck energy, the theory can be approximated by the previously described Planck aether model, which can be viewed as a superfluid consisting of Planck masses, leading to special relativity as a dynamic symmetry in the asymptotic limit of low energies.
Onset of Thermosolutal Convection in a Liquid Layer Having Deformable Free Surface – II. Overstability
Authors: Dandapat B. S. , Kumar B. P. 
Published: February 2015

Abstract
The onset of thermosolutal convection driven by a temperature and concentration dependent surface tension is investigated for a thin layer of fluid having a deformable free surface. It is shown that there exist two Crispation numbers (Cr) for oscillatory modes of instability. It is further shown that Cr and the frequency of the oscillatory mode are strongly coupled for large values of Cr. It is found that Cr destabilizes the system for both cases, salted from below and salted from above
The 14N Nuclear Quadrupole Coupling in E- and Z-C-Cyanomethanimine; its Prediction from Restricted Hartree-Fock Wave Functions and its Experimental Determination by High Resolution Microwave Spectroscopy
Authors: Krause H. , Sutter D. H. 
Published: February 2015

Abstract
The 14N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH - C ≡ N, produced by flash pyrolysis from (CH3)2N -C ≡ N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane):

The observed hfs multiplets were predicted with reasonable accuracy from RHF/6-311G** field gradients, once the latter had been scaled appropriately to compensate partly for the typical errors in the RHF-wave functions. The hitherto unmeasured 14N hyperfine multiplets of the related pyruvonitriles, H - N = C(CH3) - C ≡ N, are predicted.
Preparation of Octabromoditechnetate(III,II), [Tc2Br8]3- and the Vibronic Structure of the δ → δ* Transition
Authors: Peters G. , Skowronek J. , Preetz W. 
Published: February 2015

Abstract
The dinstinct vibronic structure of the δ → δ* transition of Cs3[Tc2Br8] with its mixed valence is well resolved at 6 K. The electronic origin at about 5970 cm-1 is split into four components, each giving rise to progressions entirely assignable in terms of nν1 and nν1 + ν2 up to n = 9, utilizing the totally symmetric stretching modes ν1(TcTc) and ν2(TcBr) exclusively.
Hydrogen in Electrodynamics. VIII The Half-Integer Spin
Authors: Sallhofer Hans 
Published: February 2015

Abstract
After a discussion of the one-component Schrödinger (1926) and the four-component Dirac(1928) representation of hydrogen it is shown that the six-component electrodyamic picture turns out to be considerably simpler and clearer. The computational effort is reduced to a fraction.
Far-Infrared Laser Magnetic Resonance Detection of CH2Cl
Authors: Temps F. , Wagner H. Gg. , Wolf M. 
Published: February 2015

Abstract
New Far Infrared Laser Magnetic Resonance (LMR) spectra have been detected in the reaction of Cl atoms with CH2CO. Based on chemical and kinetic evidence they were assigned to CH2Cl radicals. The assignment was substantiated by subsequent experiments which employed the reactions of F atoms with CH3Cl and Na atoms with CH2Cl2, respectively. The three different sources yielded identical spectra
NMR Characterization of Half-integer Quadrupolar Nuclei in Solids
Authors: Amoureux J. P. 
Published: February 2015

Abstract
This article describes a few aspects of NMR characterization of half-integer quadrupolar nuclei in powder samples which are either static or rotating around one fixed axis (M.A.S. and V.A.S. techniques). The simultaneous occurence of C.S.A. and quadrupole interactions with possible noncoincident tensors is discussed. Two experimental limitations are taken into accout: the sample spinning speed and the RF-amplifier power
Presparking Effect in Spark Source Mass Spectrometry
Authors: Harfoush A. , Soulayman S. Sh. 
Published: February 2015

Abstract
The Relative Sensitivity Factor (RSF) in Spark Source Mass Spectrometry analysis was found to be dependent on the number and duration of previous sparking periods. This dependency becomes very strong when dealing with volatile elements. By statistical analysis of experimental RSF values it was found that there is a linear correlation between In (RSF) of some trace elements and their boiling temperature. This correlation fails when dealing with volatile elements and carbon. It was found that elements with a large diffusion coefficient have a large RSF.
Theoretical Melting Curves of Alkali Halides
Authors: Soulayman S. Sh. 
Published: February 2015

Abstract
An analysis of the melting curves of alkali halides is given. The study is based on the Improved Unsymmetrized Self-Consistent Field Method (IUSCFM) for strongly anharmonic crystals with complex lattice and the energy, entropy and Ross’s criterions in calculating the melting curves of alkali halides. The anharmonicities up to sixth order have been taken into consideration. The energy criterion was proven to be the most correct one along the melting curves of the high pressure modification (CsCl structure) while the entropy and Ross's criterions lead to a little better agreement with experiment than the energy criterion when dealing with rocksalt structure. Calculations of the melting curves of KCl and CsCl are compared with the experimental results.
Quantum-Mechanical Concepts in the Waveguides Theory
Authors: Marinescu N. , Apostol M. 
Published: February 2015

Abstract
A Klein-Gordon-type equation is derived for the wave propagation in an ideal, uniform waveguide, and its quantum-mechanical interpretation is given. The "cross-section" concept is introduced for a waveguide and the power transmission factor is obtained by using standard methods of quantum mechanics. The spinorial formalism is also employed for deriving the equivalent Dirac-type equation, and the perturbation theory is applied for computing the frequency shifts. The general applicability of the quantum-mechanical concepts to the waveguides theory is discussed
ENDOR Studies of X-Irradiated Single Crystals of Sulphamethoxazole
Authors: Krzyminiewski R. , Lund A. 
Published: February 2015

Abstract
Single crystals of sulphamethoxazole were X-irradiated at 273 K. ESR and ENDOR spectra were obtained at 100 K. The free radicals stable at room temperature are formally formed by abstraction of a hydrogen atom from the methyl group of the molecule. The unpaired electron is delocalized in the isoxazole ring. The assignment is supported by comparisons of spin densities obtained experimentally and by semiempirical molecular orbital calculations
Thermodynamic Study of Ce4+ /Ce3+ Redox Reaction in Aqueous Solutions at Elevated Temperatures: 1. Reduction Potential and Hydrolysis Equilibria of Ce4+ in HCIO4 Solutions
Authors: Bilal B. A. , Müller E. 
Published: February 2015

Abstract
The redox potential (E) of the couple Ce4+/Ce3+ has been determined up to 368 K by means of cyclic voltammetric measurement in aqueous HClO4 solutions with cHClO4 decreasing from 7.45 to 0.023 mol kg-1 . A constant potential of (1.741 V)298 K, resp. (1.836 V)368K, indicating the existence of pure unhydrolysed Ce4+ was obtained at cHClO4 ≥ 6.05 m. At lower HClO4 concentration, the potential as a function of the HClO4 molality, as well as of the pH shows 4 further distinct steps. At 298 K, for instance, the potential became nearly constant at pH values of 0.103, 0.735,1.115, after which it drastically decreased, respectively at 1.679, just before the precipitation of Ce(OH)4 occurred. The curves indicate obviously the stepwise formation of the Ce(IV) mono-, di-, tri- and tetrahydroxo complexes. The slope of the curves E vs. pH increased gradually with increasing temperature. ΔS and ΔH of the redox reaction were determined as functions of T at the different HClO4 concentrations. ΔSis positive at cHClO4 > 1.85 m and turns to be negative at lower concentrations. ΔHis negative at all HClO4 concentrations studied. The cumulative formation constants ßi, of the Ce(IV) hydroxo complexes and the corresponding hydrolysis constants (Kh)i were calculated. An unusual decrease of ßi with increasing temperature has been discussed
Cu NQR Study in a High-Jc Superconductor YBa2Cu3O6.1Ix
Authors: Ossipyan Yu. A. , Zharikov O. V. , Matukhin V. L. , Anashkin V. N. , Safin I. A. , Pogorelcev A. I. , Teitelbaum G. B. 
Published: February 2015

Abstract
NQR-spectra and nuclear relaxation of 63Cu in ceramic samples of the Y - Ba - Cu -O system with various oxygen content have been compared with those in iodinated YBa2Cu3O6.1.
Cu-NQR Frequencies and Linewidths in High- Tc Superconductors
Authors: Gärtner S. , Riesemeier H. , Kitaokab Y. , Müller V. , Lüders K. , Kaldis E. , Rusiecki S. 
Published: February 2015

Abstract
The Cu-NQR lines of various high-Tc superconductors at the Cu(2) site appear between 15 and 40 MHz. There exists an experimental correlation showing that the NQR frequency increases with decreasing Tc. By comparison, it can be concluded from these results that a formal valence state of the Cu ion around 2 + is favourable for superconductivity. All lines exhibit a strong broadening compared to CuO2 crystals, which is attributed to lattice modulations within the CuO2 layers. This effect also influences the temperature dependence of the linewidth in YBa2Cu3O7-δ .
The 111mCd Nuclear Quadrupole Interaction in CdCl2 and its Monohydrate
Authors: Fraenzke Th. , Butz T. , Lerf A. 
Published: February 2015

Abstract
The 111mCd nuclear quadrupole interaction in CdCl2 and CdCl2 • H2O was determined in the temperature range from 77 K to 783 K and 363 K, respectively, by time differential perturbed angular correlation. In addition, both the crystallization of the monohydrate from solution and its dehydration were monitored in situ.
A63,65Cu and 127I Nuclear Quadrupole Resonance and X-Ray Crystallographic Study of a Low-Temperature Phase of the (2-picoline) Copper (I) Iodide Dimer
Authors: Habiyakare Augustin , Lücken Edwin A. C. , Bernardinelli Gerald 
Published: February 2015

Abstract
The temperature-dependence of the 63Cu and 127I NQR spectra of bis(2-picoline) Copper(I) Iodide reveals the existence of a phase change at 250 K. An X-ray crystallographic study of the low-temperature phase reveals that the iodine-bridged dimeric structure, which was observed at room-temperature, is retained in the low temperature phase but that the bond-lengths and, particularly, the bond-angles of the central four-membered ring are considerably modified.
Dioxin Precursors: NQR Studies of Group 1 and Related 2,6-Dichlorophenolate and 2,4,6-Trichlorophenolate Salts
Authors: Wulfsberg G. , Shadid K. , Farris B. , Monn J. , Bonner T. , Yanisch J. , Weiss Al. 
Published: February 2015

Abstract
The 81Br and 35Cl NQR spectra of anhydrous Group 1, tetraalkylammonium, and thallium(I) 2,6-dichlorophenolates, 2,4,6-trichlorophenolates, and 4-bromo-2,6-dichlorophenolates were searched for evidence of solid-state cation-organochlorine interactions that might, for example, be (in part) responsible for the difference in the thermal decomposition reactions of these salts (to give the supertoxic environmental pollutants, the polychlorinated dibenzodioxins) versus those of the corresponding Group 11 chlorophenolate complexes, which do not decompose to dioxins.
For cations ranging in size from tetraethylammonium to potassium, the total range of 35Cl NQR frequencies in 2,6-dichlorophenolate and 2,4,6-trichlorophenolate salts is only 1.401 MHz, which, although larger than the 0.7 MHz range likely in molecular chlorocarbons, is smaller than in individual chlorophenolates of copper(I) and silver(I) (up to 2.0 MHz). In sodium and thallium(I) 2,4,6-trichlorophenolates substantially large frequency shifts (ca. 2.0 MHz) occur, to higher frequencies for the para-chlorines and lower frequencies for the ortho-chlorines (Na only). These disappear even in closely related compounds and show a pattern that seems unrelated to the decomposition products of the chlorophenolates.
79Br and 127I NQR of tert-Butylammonium Halides and Crystal Structure of (CH3)3CNH3
⊕ Br⊖
Authors: Shabazi Morteza , Dou Shi-qi , Weiss Alarich 
Published: February 2015

Abstract
The 79Br and the 127 I NQR spectrum of tert-butylammonium bromide and iodide, respectively, was studied as a function of temperature. No phase transition was observed for the bromide in the temperature range covered. The 79Br NQR frequency is 9.056 MHz at 113 K and increases with increasing temperature (10.040 MHz at 293 K).
The NQR spectrum reveals a phase transition of ( CH3 ) 3 CNH⊕
3I⊖ around 360 K with pronounced hysteresis. The nuclear quadrupole coupling constant of 127 I is 69.335 MHz with an asymmetry parameter of 0.154 for the high temperature phase at T = 370 K. For the low temperature phase the corresponding values are 67.136 MHz and 0.081 at 300 K.
The crystal structure of tert-butylammonium bromide was studied at room temperature. The compound crystallizes orthorhombic, space group D152hPbca, with 4 formula units in the unit cell, a = 1832.1 pm, b = 918.5 pm, c = 899.8 pm. The crystal structure and hydrogen bond system are discussed in connection with the NQR results.
35Cl NQR and Crystal Structure Studies of Salts of Chlorodifluoro- and Dichloroacetic Acid
Authors: Basaran Reha , Dou Shi-qi , Weiss Alarich 
Published: February 2015

Abstract
The 35Cl NQR spectra of several chlorodifluoroacetates were studied as a function of temperature, including the acid ClF2CCOOH. The cations were: Ammonium, guanidinium, paramethylanilinium. Also some acid salts M⊕ClF2CCOO⊖ • n - ClF2CCOOH ( n > l ) were studied by 35Cl NQR. The bleaching temperatures of the NQR signals were determined. In the para-methylanilinium salt and in the guanidinium salt a phase transition has been observed. The crystal structure of guanidinium chlorodifluoroacetate has been determined at room temperature (a = 1089 pm, 6 = 845 pm, c = 832 pm, space group Pnma, Z = 4). For comparison, guanidinium dichloroacetate was studied by 35Cl NQR and by X-ray diffraction, too: P21/c, Z = 4 , a = 804pm, b = 1202 pm, c = 1080 pm, ß = 131.58°. For guanidinium chlorodifluoroacetate and chlorodifluoroacetic acid, the 35Cl spin lattice relaxation time T1 and the line width have been followed up as a function of temperature. Therefrom, the activation energies of the reorientation motion of the group -CF2C1 have been determined to be 14 kJ • mol-1 (from T1) and 12.5 kJ • mol- 1 (from Δv) for the pure acid and 9.2 kJ • mol-1 and 8.8 kJ • mol-1 , respectively, for the guanidinium salt.
High Pressure Studies of Tetrachloro-o-benzoquinone by NQR Spectroscopy
Authors: Koziol Piotr 
Published: February 2015

Abstract
Tetrachloro-o-benzoquione (TOB) crystallizes in two different forms. The two forms, Sample I and Sample II, show different phases and NQR spectra. When subjected to pressures higher than about 40 MPa the a phase is converted to the y phase. X-ray powder patterns studies as well as DTA measurements have confirmed this result. Heating the y phase above 310 K reverses this process.