bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dyes Adsorbed at Ag‐Colloids: Substitution of Fluorescence by Similarly Efficient Surface Fluorescence and Surface Raman Scattering
Authors: Pettinger B. , Gerolymatou A. 
Published: July 2012

AbstractWith the addition of Ag‐sol to extremely diluted rhodamine 6G solutions (ca. 10−10 M/l) the prevalent fluorescence can be replaced by surface fluorescence and surface enhanced resonance Raman scattering (SERRS) of similar intensity, however only in presence of coadsorbed anions such as chloride. For strong bands the Raman cross sections are as high as 10−19 cm2 sr−1 molecule−1. Referred to the extinction of the sol which is much larger than that of the dye solution, the mean quantum yield for the surface Raman scattering is estimated to 0.0004. In addition, SERRS consisting of a set of fundamental vibrations, overtones and combination modes and a broad continuum shows throughout the spectral range a significant, but identical polarisation (I(sp): I(ss) = 0.55), whereas the solution as well as surface fluorescence is completely depolarised.
Tracerdiffusion von64Cu in γ‐Kupferbromid im Vergleich mit Ergebnissen aus Leitfähigkeits‐ und Kernresonanzmessungen
Authors: Schäfgen H.‐P. , Richtering H. 
Published: July 2012

AbstractIn order to elucidate the mechanism of atomic transport of copper ions in γ‐CuBr the tracer diffusion coefficient of64Cu had been determined between 170 and 340°C. The ionic conductivity was measured for comparison. — The tracer diffusion coefficient is found to be larger than the diffusion coefficient calculated from ionic conductivity (by a factor 5 at 170°C and 2 at 340°C). The Arrhenius plots of both are curved. Their difference, however, is linear and coincides with the diffusion coefficient derived from nmr relaxation rates. — From the observed differences between the three diffusion coefficients it is concluded that atomic transport of Cu+in γ‐CuBr takes place to a considerable extent via associated pairs of interstitial Cu+‐ions and cation vacancies.
Millimeter Wave Spectrum and Structure of Isoselenocyanic Acid, HNCSe
Authors: Vogt Jürgen , Winnewisser Manfred 
Published: July 2012

AbstractThe rotational a‐type spectra of the five most abundant isotopomers of HNCSe were recorded in natural abundance. Using Watson's S‐reduced Hamiltonian the rotational and some centrifugal distortion constants could be determined for the ground vibrational state of the various isotopic species. With the aid of these constants the restructure of HNCSe could be refined and the parameter specifying the quasilinearity of the molecule could be estimated.
On the Mechanism of Formation of Formation of Positronium in Polar Solvents
Authors: Alfassi Zeev B. 
Published: July 2012

AbstractIn this paper it is shown that various results on the effect of solutes and temperature on the formation of positronium in polar solvents can be better explained by a hybrid model between the “Ore‐gap” model and the “spur” model, stating that both contribute to the formation of positronium but the inhibition in case of partial inhibitors as well as the enhancement is due only to the second model. Complete inhibition is explained as due to the removal of positronium by its oxidation rather than preventing its formation.
Electrical and Magnetic Properties of the Molten Ag – TlTe System
Authors: Uemura Osamu , Suzuki Kiyomi , Satow Tsuneo 
Published: July 2012

AbstractThe electrical conductivity, the magnetic susceptibility, and the thermoelectric power of the liquid Ag – TlTe system have been obtained, respectively, as a function of temperature and composition from near the liquidus temperature up to about 900°C. These mixtures exhibit a sharp decrease in electrical conductivity and a change in sign of thermoelectric power around the stoichiometric composition AgTlTe. Measurements of magnetic susceptibility also indicate a marked anomaly at this composition. These electronic properties for the molten Ag – TlTe system are discussed in the light of current transport theories employed in the amorphous and liquid semiconductors.
Radiative Lifetimes of Optically Excited Cu and Au Atoms in Rare Gas Matrices
Authors: Schrittenlacher W. , Kolb D. M. 
Published: July 2012

AbstractThe time dependence of the fluorescence decay for optically excited Cu and Au atoms in rare gas matrices was investigated. The metastable 2D3/2 and 2D5/2 states of these atoms exhibit lifetimes in the millisecond regime. For Cu in Ne, emission from the matrix‐relaxed Cu 4p‐level was also observed. For fluorescence from 2D states, a multiple decay was observed for Cu in all matrices despite careful annealing. This multiple decay is most likely due to metal atoms at slightly different matrix sites which cannot be distinguished energetically by their matrix shifts. Obviously lifetime measurements are extremely sensitive to the matrix environment. For matrix‐isolated Au atoms a transition between the spin‐orbit split 2D states was observed for the first time.
Investigation of a Rechargeable Electrochemical Cell with Polyacetylene Electrodes
Authors: Broich B. , Hocker J. 
Published: July 2012

AbstractElectrochemical cells with polyacetylene, (CH)x, as active anode and cathode material have been built. The cells were of the type (CH)x/R4N+ClO4⊖/(CH)x. The cells with different electrode thicknesses and areas, respectively, showed all the same typical charging and discharging behaviour. From the experimental data the change of molar doping concentration during charge and discharge, charge capacity, energy – and power density are evaluated. – The cell performance is limited by internal losses and electrochemically induced irreversible processes, which also limit the rechargeability to a few cycles.
Ion‐Exchange Kinetics. A Qualitative Quasi‐Electrical Approach
Authors: Du Preez J. G. H. , Gerber T. I. A. , Wantenaar D. C. 
Published: July 2012

AbstractOne of the possible mechanisms operating in ion‐exchange kinetics is film‐diffusion. The typical rate law describing this process can also be derived by viewing the exchange system as an electrical circuit containing a seat of emf, a resistor and a capacitor. The loading of the ion exchanger can be likened to the charging of the capacitor, and a qualitative description is given of the influence of the chemical potential as the driving force for the ion exchange process.
Optical Activity of Oriented Molecules. 10.Analysis of the n‐π Transition of 4‐en‐3‐one Steroids and Comparison of the Order Parameters of Host and Guest in a Compensated Nematic Phase
Authors: Altschuh J. , Weiland R. , Kosack J. V. , Kuball H.‐G. 
Published: July 2012

AbstractWhile different substitution in the 17β‐position of 4‐en‐3‐one steroids (testosterones, progesterones) does not influence the CD spectra, the CD of the anisotropic solutions (ACD) undergoes a drastic variation of the band shape connected with a change from negative to positive curves. From this variation and the wavelength dependence of the degree of polarization of the UV spectra results that at least two progressions of vibrations (v̄00 + nv̄1 and v̄00 + v̄x + nv̄1) are responsible for the band structure of the n‐π* transition of the 4‐en‐3‐one chromophore where the totally symmetric (v̄1) and the non‐totally symmetric vibration (v̄x) are about 1200 and 600 cm−1, respectively. Furthermore, this variation of the ACD spectra for constant temperature and solute (guest) to solvent (host: cholesteryl chloride/cholesteryl laurate) ratio is a consequence of a change of the order parameter of the guest and the host which have been determined in the same solution by ACD and AORD, respectively. Most variation of the guest order can be understood by the proportionality to the anisotropy of the polarizability 2α33‐α22‐α11 or the length to width ratio 2l3‐l2‐l1 if no hydroxy group is present. Here a very high order exists. For some compounds the high order of the guest is connected with a strong decrease of the host order. In general, the alteration of the host order is not a function of the order of the guest i.e. at least one molecular property responsible for the ordering of the guest should be different from those properties of the guest which alterate the order of the host.
Kinetics of Proton‐Transport‐Coupled ATP Synthesis in Chloroplasts. Activation of the ATPase by an Artificially Generated ΔpH and Δψ
Authors: Gräber Peter , Junesch Ulrike , Schatz Güther H. 
Published: July 2012

AbstractThe kinetics of proton transport coupled ATP synthesis at the chloroplast membrane was investigated upon energization of the membrane by an artificially generated ΔpH and an electric potential difference, Δψ. Using a rapid mixing system, rates of ATP synthesis were studied at short reaction times (<150 ms) where all relevant parameters (ΔpH, Δψ, substrate and product concentrations) remain practically constant at their initial values. Under these conditions it was found:

The maximal rate of ATP synthesis obtained under these artificial conditions is the same as that obtained by light‐induced ATP synthesis.
The turnover number of the ATPase is 410 s−1.
The rate of ATP synthesis depends in a sigmoidal way on the transmembrane electrochemical potential difference of protons, Δψ, regardless of the relative contributions by ΔpH and Δψ.
The functional dependence of the rate of ATP synthesis on Δμ does not reflect the kinetics of the catalytic events at the ATPase but the transformation of the ATPase from an inactive to a catalytically active state.
The binding of two protons to the ATPase from the inside of the membrane is necessary for activation.
Structural Phase Transition due to a Release of Bound Water in Phospholipid Bilayers at Temperatures below 0°C
Authors: Grünert M. , Börngen L. , Nimtz G. 
Published: July 2012

AbstractMeasurements of dielectric and calorimetric properties and of the lamellar repeat distance revealed a structural phase transition at temperatures below 0°C in hydrated phospholipid (DPPC) bilayers. The transition is marked 1. by a jump of the dielectric constant at microwave frequencies, 2. by a jump of the lamellar repeat distance, and 3. by an enthalpy of transition. These observations are interpretated by a change of the amount of bound water. Below the transition temperature only seven H2O molecules per lipid molecule are left bound as interlamellar water independent on the amount bound at higher temperatures. The observed loss of bound water at this subzero temperature phase transition may represent a physical process for irreversible freezing effects.
The Temperature Dependence of the Properties of Electrolyte Solutions. VI. Triple Ion Formation in Solvents of Low Permittivity Exemplified by LiBF4 Solutions in Dimethoxyethane
Authors: Barthel J. , Gerber R. , Gores H.‐J. 
Published: July 2012

AbstractInvestigations in the temperature range −45 ≤ θ/°C ≤ + 25 on LiBF4 solutions in dimethoxyethane from infinite dilution to saturation permit to exemplify the features of conductance in solvents of low permittivity. Conductance measurements on thoroughly purified materials with the help of a measuring equipment known to produce precise data yield a complete set of conductance curves from infinite dilution to saturation at all temperatures of the program. The conductance curves show a minimum and a maximum of equivalent conductance and the change from positive to negative and once more to positive temperature coefficients of conductance. Various methods both for the evaluation of the limiting conductances, Λ∞, and the formation constants of ion pairs, KA, triple ions, KT, are critically discussed and reliable data for the LiBF4 solutions in dimethoxyethane at all temperatures of the program are communicated.
Static Light Scattering Experiments with a Critical Isobutyric Acid (COOD)/Deuterium Oxide Mixture Above its Critical Solution Temperature
Authors: Oswald U. , Belkoura L. , Jungk M. , Woermann D. 
Published: July 2012

AbstractStatic light scattering experiments are carried out with an almost critical mixture of isobutyric acid (COOD) and D2O (mole fraction of isobutyric acid (COOD) xDA = 0.11; temperature of phase separation TP = 45.9°C) to determine the critical amplitude of local concentration fluctuation. The following results are obtained: critical amplitude of local concentration fluctuations ξ0 = (3.1 ± 0.2) · 10−8 cm; critical exponent of correlation length of local concentration fluctuations: ν = 0.63 ± 0.01; critical exponent of susceptibility: γ = 1.26 ± 0.01. The values of the critical exponents v and γ are in good agreement with theoretical values predicted for binary liquid mixtures. The system‐specific parameter (0 of the system isobutyric acid (COOD)/D2O is slightly smaller (about 10%) than the corresponding value of the system isobutyric acid (COOH)/H2O (xcHA = 0.11; Tc = 26.1°C) reflecting differences between the intermolecular forces in the two systems.
Excess Properties of Binary Mixtures Composed of a Polar Component and an Alkane
Authors: Fuchs Reiner , Krenzer Luise , Gaube Johann 
Published: July 2012

AbstractMixtures containing a polar component and an alkane show a transitional behaviour between non‐associated and associated mixtures. The excess enthalpy and the excess Gibbs energy can be described by the quasichemical approximation with a temperature dependent interchange parameter. The excess entropy is given by SE = SconfE + SINTE. The first term is due to the non‐randomness of the mixture. The second term is correlated to HE. Using this correlation GE, HE and TSE can be roughly predicted. — Excess enthalpies and vapor pressure data were measured in order to supplement excess property data.
Enthalpies of Formation at 1373 K of the Liquid Alloys Ag + Au, Ag + Sn, Au + Sn and Ag + Au + Sn
Authors: Rakotomavo J. , Gaune‐Escard M. , Bros J. P. , Gaune P. 
Published: July 2012

AbstractThe enthalpies of formation ΔHM of the liquid binary (Ag + Au, Ag + Sn and Au + Sn) and ternary alloys (Ag + Au + Sn) were measured at 1373 K by direct calorimetry on the whole concentration range. The ternary investigations were conducted along the sections XAg/XAu = 1/4, 1/1, 6.25/3.75 and 7/3 with XSn < 0.60 and XAg/XSn = 3/7, 1/1 and 7/3 with XAu < 0.60. The apparatus used was a very high temperature calorimeter with a sensing device consisting in 20 Pt + 6% Rh/Pt + 30% Rh thermocouples. The experimental uncertainty was quoted at 10%. The results obtained for the limiting binary systems were compared with those, numerous and contradictory, reported in literature. The enthalpies of formation of the ternary alloys Ag + Au + Sn can be represented using a modified Kohler's equation including a supplementary correction term to the binary contributions.
Optisches Verfahren zur Bestimmung der Geschwindigkeit einzelner suspendierter kolloider Teilchen
Authors: Busch D. , Haase G. , Zörgiebel F. 
Published: July 2012

AbstractUsing components of a standard electrophoresis equipment (Zytopherometer) a stroboscopic dark field method was developed to record colloidal particles moving in an electric field. An argon ion laser served as a strong illuminant, a TTL electronic equipment provided the synchronization of electric field pulses, illumination and camera shutter. With this method speeds of particles ‐ e.g. soot dispersed in cyclohexan – could be measured at field strengths from zero (Brownian movement) up to 3 · 105 V/m (beginning of turbulence).
The Application of Generalized Nernst‐Planck Equations to the Description of Ion Retention in the Hyperfiltration of Mixed Electrolyte Solutions through a Neutral Membrane
Authors: Vonk M. W. , Smit J. A. M. 
Published: July 2012

AbstractPseudo‐binary Nernst‐Planck equations have been employed to derive expressions for the ion retention in a neutral membrane as a function of the volume flux. The derivation requires an integration across the membrane. In case of a solution of two ion species this integration is exact. For solutions of three kinds of ions the desired result is only obtained along an approximative route and then still only in certain limiting cases.Nevertheless anomalies in the retention observed in systems containing three types of ions are predicted by the developed theory.
Thermal, Conductivity, Density, Viscosity, and Prandtl‐Numbers of Ethylene Glycol‐Water Mixtures
Authors: Bohne D. , Fischer S. , Obermeier E. 
Published: July 2012

AbstractThermal conductivity, density, and viscosity of ethylene glycol – water mixtures have been measured. The measurements have been performed in the temperature range from ‐−20°C to 180°C for thermal conductivity, from ‐−10°C to 150°C for density, and from – 10°C to 100°C for viscosity. Prandtl‐Numbers calculated with the own experimental data and literature values of specific heat capacity are presented in dependence of temperature and concentration.
Acid Base Reactions Between Acridine Orange and Substituted Phenols in Benzonitrile Part I. Thermodynamics of Association and Ionic Equilibria
Authors: Süttinger Rudolf , Strohbusch Frank 
Published: July 2012

AbstractProton transfer reactions of the five substituted phenols 3‐Cl−4‐nitrophenol CNP, 4‐nitrophenol NP, 3‐methyl−4‐nitrophenol MNP, 4‐Cl−3,5‐dimethylphenol CMP, and 3,5‐dimethylphenol DMP with acridine orange, and the formation of hydrogen bonded complexes AHA− of the anions A− of CNP, NP, and MNP with the respective phenols AH in benzonitrile solution were investigated by means of absorption spectroscopy. Thermodynamic data for the formation of the complexes AHA− and of the ionic reactions (1) and (2) of CNP, NP, and MNP with the acridine orange base B magnified image and for the reactions (2) and (3) of CMP and DMP with B were determined. The reactions (1) ‐ (3) are exothermic. The absolute values of ΔH1 increase with the acidity of the phenols. The formation enthalpies of the hydrogen bonded anions AHA‐ are much larger than ΔH1, so that ΔH2 is mainly determined by this association. On the other hand there is no significant difference between ΔH2 and ΔH3; thus the hydrogen bond formed between a phenol and a complexed anion AHA‐ is very weak. Substituent effects on the acidity of phenols are about twice as large in benzonitrile as in aqueous solution.
Acid Base Reactions Between Acridine Orange and Substituted Phenols in Benzonitrile Part II. Kinetics: An Extended Eigen Mechanism of Proton Transfer
Authors: Süttinger Rudolf , Strohbusch Frank 
Published: July 2012

AbstractThe kinetics of proton transfer between five substituted phenols (AH) and the acridine orange base (B) are studied in benzonitrile solution using the temperature jump method. In the overall reactions (1)–(3)magnified imagethe formation and dissociation of an intermediate ion pair A‐.. HB+is rate determining. The rate constants of the bimolecular recombination of the ions to the ion pair arekb1,kb2, andkb3. Their values are in the range (0.18‐ 1.7) · 109M‐1s‐1(25 °C,I= 0.1 M).kb2andkb3do not depend on the pKof the phenol involved, although these rates are not diffusion controlled. The rate of proton transfer from the protonated acridine orange (BH+) to the free anions (A‐) does depend to some degree on the acidity of the corresponding phenol. In the case of the 3‐methyl‐ 4‐nitrophenolate ion this rate is diffusion controlled, as shown by the dependence ofkb1on the temperature and the ionic strength. Lower limits for the formation constants of the ion pairs are estimated from the rate data. The equilibria and the kinetics are discussed in terms of an extended Eigen scheme of proton transfer, and the separate steps of anion solvation by hydrogen bonding to phenol molecules shown to depend in different ways on the basicity of the anion.
A Mass Spectrometric Investigation of Iron(II)‐Iodide
Authors: Grade M. , Rosinger W. 
Published: July 2012

AbstractA consistent set of thermodynamic data for solid FeI2and for molecules which constitute its equilibrium gas phase is provided, based on measurements by the high‐temperature mass spectrometry and electron impact techniques. Second‐ and third‐law heats of formation, atomization and reaction, as well as individual Fe‐I bond strengths, are reported for the species FeI2(g), Fe2I4(g), Fe2I2(g) and for solid FeI2. Partial and total pressure data are also given, as well as an up to date literature survey of thermochemical data for the FeI2system.
Phase Equilibria and Density Calculations for Mixtures in the Critical Range with Simple Equations of State (Invited Lecture)
Authors: Vidal J. 
Published: July 2012

AbstractThe “Supercritical solvency” is connected to the liquid‐like density of gases at high pressure, and to the high sensitivity of this density to temperature and pressure in the near critical range of the solvent. The dissolution of the supercritical solvent in the liquid phase may also lead to liquid liquid equilibria, whose continuity with vapour liquid equilibria has been shown. – Simple methods, like cubic equations of state give a qualitative representation of such properties. However new formulations of the equation of state should be used to obtain a satisfactory prediction of the pVT properties in the critical range, while maintaining the simplicity of the cubic equation of state. The classical mixing rules cannot take into account the intermolecular forces existing between the solutes and the solvent, which often greatly differ in size, shape and polarity, and our experience of the classical liquid‐liquid equilibria can help us in the formulation of new and effective methods, such as the “density dependant local composition” mixing rules. Such theories contain empirical binary parameters and their application needs experimental data. – However, prediction methods based on the concept of group contribution are being developed, and can help the selection of selective supercritical solvents.
Application of a Local Composition Equation of State to Supercritical Fluid Phase Equilibrium Problems
Authors: Brignole E. A. , Skjold‐Jørgensen S. , Fredenslund A. A. 
Published: July 2012

AbstractThe group contribution equation of state (GC‐EOS) is used for the prediction of phase equilibria related to supercritical extraction of ethanol from aqueous solutions. The calculations show that it is not possible to design an economically favourable alternative to distillation processes using CO2 as the supercritical solvent. This is in accordance with the available experimental evidence. – Further calculations indicate that the use of light hydrocarbons as supercritical or near‐critical solvents may be a very attractive alternative for the recovery of pure alcohol from dilute aqueous solutions.
Heats of Mixing of Water + Hydrocarbons at High Temperatures and Pressures (Invited Lecture)
Authors: Wormald C. J. 
Published: July 2012

AbstractMeasurements of the excess enthalpy HE of mixtures of water + hydrocarbon vapour in the region 363 to 698 K and at pressures up to 12 MPa are described. Results obtained at low temperatures and pressures yield values of the cross term second virial coefficient B12. Analysis of results on several mixtures containing steam show that in its interaction with n‐alkane water has effective Lennard‐Jones parameters ε/k = 285 K and σ = 0.27 nm. Combining rules for ε12 in the water + alkane interaction are established. For alkanes above n‐pentane the isothermal HE (x = 0.5), p curves show maxima at pressures well below saturation. Results for all mixtures can be fitted using a new association model. HE measurements on water + benzene show clear evidence of a specific interaction. The enthalpy of formation of the water + benzene complex is ΔH = −9 kJ mol−1.
Continuous Viscosity Measurements in Order to Observe the Solubility and Miscibility of Carbon Dioxide in a Crude Oil
Authors: Killesreiter Hermann 
Published: July 2012

AbstractA spring‐bellows‐capillary viscometer is now semi‐automatically working and makes, thus, a continuous record of viscosity data possible. These very structure sensitive viscosity measurements have been used to observe the solubility of carbon dioxide in a crude oil, and to demonstrate under proper conditions the lack of miscibility between both compounds. Some measurements with other gases such as nitrogen, methane, and propane are shown for comparison.