bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamische Messungen der Bindungsenthalpien kleiner Liganden mit Nukleinsäuren I. Anlagerung von Ethidiumbromid an DNA und Apurinsäure
Authors: Burkart W. , Klump H. 
Published: July 2012

AbstractThe enthalpy of binding of ethidiumbromide (EB) to double‐ and single‐stranded DNA of two different species and to apurinic acid has been measured by means of an isothermal mixing calorimeter. Equilibrium dialysis served as a tool to determine the extent of binding of EB. — At 5, 20, and 35 °C the binding enthalpies were −20.3, ‐23,6, and −33.5 kJ/mol EB, respectively, for the binding to single‐stranded calf‐thymus DNA (ssCT) in SSC‐buffer and −21.4, 28.5, −36.4 kJ/mol EB for the binding to dsCT. In a tenfold diluted buffer the values were ‐39.4, −62.8, −72.0 kJ/mol EB for ssCT and −21.4, −30.8, and 36.0 kJ/mol EB for dsCT.
Thermodynamische Messungen der Bindungsenthalpie kleiner Liganden mit Nukleinsäuren II. Anlagerung von Oligopeptiden an DNA
Authors: Burkart W. , Klump H. 
Published: July 2012

AbstractThe enthalpy of binding of different amines and oligopeptides to double‐ and single‐stranded DNA has been measured by means of an isoperibolic mixing calorimeter. Measurements were performed in diluted Citrate buffer at 25 °C. The binding of the peptides to double‐stranded DNA did not result in any measurable enthalpy change (except LysTrpLys), binding of the peptides could be demonstrated by equilibrium techniques. Binding to single‐stranded DNA yielded enthalpies up to ‐30 kJ/mol of peptide bound. The binding enthalpy of some of the peptides depends markedly of the degree of binding, which has been determined by equilibrium dialysis
The Viscosity of Mixtures of Hydrogen with Three Noble Gases
Authors: Clifford A. A. , Kestin J. , Wakeham W. A. 
Published: July 2012

AbstractThe paper reports new absolute measurements of the viscosity of hydrogen and its binary, gaseous mixtures with neon, argon and krypton at 25 °C and 35 °C and at a pressure of 0.1 MPa. The measurements were carried out in a high‐precision oscillating‐disk viscometer and their accuracy is estimated as one of ±0.2%. — The results have been compared with predictions based on recent intermolecular pair potentials for the interactions of hydrogen with the monatomic gases derived from spectroscopic and molecular beam studies. The calculations, which have been carried out with second‐order kinetic theory expressions, are not entirely consistent with the experimental results. The experimental results have been employed to determine binary diffusion coefficients for the three systems. The viscosity data have also been employed to predict the thermal conductivity of the mixtures with the aid of the most accurate kinetic theory formulae available for systems containing polyatomic components. A comparison with accurate thermal conductivity data indicates that the equations, which are first‐order approximations, are not sufficiently accurate for systems containing components of widely disparate mass.
Spectral Sensitization of ZnO Film Electrodes by the J‐Aggregate of Cyanine Dyes
Authors: Hada H. , Yonezawa Y. , Inaba H. 
Published: July 2012

AbstractMagnetron sputtered ZnO film electrodes were sensitized to visible light by using the J‐aggregates of four cyanine dyes. Both the sensitized anodic and cathodic photocurrents are observed but the magnitude of them considerably changes according to the kind of dyes employed. The action spectra of both photocurrents are fairly in accord with each other, not to speak of a distinct J‐band. Characteristics of carrier injection from the J‐aggregates are discussed.
Neutron Scattering Study on Three Different Phases of Toluene Adsorbed on Graphite Surfaces
Authors: Monkenbusch M. , Stockmeyer R. 
Published: July 2012

AbstractThe structure and dynamics of toluene layers adsorbed on microcrystalline graphite have been investigated by thermal neutron scattering. The structure determination by diffraction from a C6D5—CD3 layer reveals three different phases at temperatures between 40 K and 200 K. — We observed a registered 3 × 3 structure below 70 K, an incommensurate phase in the temperature interval between 70 K and 140 K and a fluid phase above 140 K. — The dynamics has been studied by inelastic incoherent scattering due to the protons of a C6H5 — CH3 (C6H5 — CD3) layer. The fluid phase shows quasielastic scattering, at 200 K the effective diffusion coefficients have been determined as D1 = 4 · 10−5 cm2/s for the ring protons and D2 = 2 · 10−4 cm2/s for the CH3 protons. The registered 3 × 3 phase shows a spectrum with features as expected from the corresponding data from 3‐dim. toluene crystals. The incommensurate phase exhibits a pseudo quasielastic scattering, which has been attributed to the scattering intensity from a 2D‐Debye solid in the low frequency region.
Investigation of Photoinduced Bond Cleavage by Time‐Resolved Resonance Raman Spectroscopy
Authors: Hub W. , Melzig M. , Schneider S. , Dörr F. 
Published: July 2012

AbstractThe photochromic behaviour of 2,3,4,4‐Tetrachloro‐1‐oxo‐1, 4‐dihydronaphthalene (“β‐TKN”) was studied by means of time‐resolved resonance raman spectroscopy in various solvents. It is shown that the results confirm the interpretation of a photoinduced homolytic rather than the one of a heterolytic cleavage of a C‐Cl bond, leading to the 2,3,4‐Trichloronaphthoxyl‐radical as the colored species.
Time‐Resolved Resonance Raman Spectroscopy: Excited Triplet States of Biological Polyenes
Authors: Wilbrandt R. , Jensen N.‐H. 
Published: July 2012

AbstractIn this paper we give an account of our studies of the excited triplet states of the biological polyenes all‐trans‐retinal, all‐trans‐β‐carotene and canthaxanthin by time‐resolved resonance Raman spectroscopy. The spectra indicate increased π‐electron delocalisation and twisting of inner double bonds of these molecules in their relaxed triplet states. The results on canthaxanthin, which are discussed in length, indicate an additional isomerisation equilibrium involving the cyclic end groups.
Transport Properties of Liquids I. Self‐Diffusion, Viscosity and Density of Nearly Spherical and Disk Like Molecules in the Pure Liquid Phase
Authors: Vogel Herbert , Weiss Alarich 
Published: July 2012

AbstractSelf‐diffusion coefficientD, viscositynand densitypof nearly spherical molecules (Tetraalkyl‐, Tetraalkoxy compounds) and of nearly disk like molecules (crown ethers) were measured (250 ≦T/K< 370). ‐1H‐NMR spin‐echo spectroscopy was applied for the measurements ofD. nwas determined via a Ubbelohde micro‐viscosimeter andpvia a vibrating densimeter. ‐Dandnfollow the Stokes‐Einstein‐Gierer‐Wirtz relation. The free‐volume theory of Cohen and Turnbull (CT) was applied to describe the experimental data quantitatively. By introducing geometrical relations for the mean free path λ and the critical free volumev*fthe CT‐model was extended and applied to the experimental results. Thereby a very satisfactory description of the measurements is attained.Dof the substances investigated can be calculated as function of the melting point andp (T). Empirically the temperature dependence ofD (T)follow an Arrhenius law. Application of the hybrid equation of Macedo and Litovitz to the experimental data shows that the temperature dependence of the transport properties in van‐der‐Waals liquids composed of spherical or disk like molecules is mainly determined by the creation of the free volume with increasing temperature.
Raman Spectrometric Investigation of the Molecular Structure of Alcohols; Conformational Dynamics of Ethanol
Authors: Richter W. , Schiel D. 
Published: July 2012

AbstractThe Raman scattering profiles of the OH stretching vibrations of methanol, ethanol, and n‐propanol in the gas phase and of ethanol in alkane solution are measured and analyzed with regard to the conformational behaviour of the molecules. — The fine structure of the profiles is largely resolved because rotational motions do not appreciably contribute to the band width as the scattering tensor is almost isotropic. In the case of ethanol, the assignment of the two sub‐bands to the trans and gauche conformers follows from the intensity ratio. An assignment to the five possible conformers is proposed for the complex profile structure of propanol. A weak satellite on the high frequency wing of the methanol profile can be assigned to a vibrational transition in the first excited torsional state. — Quantitative information on the conformational dynamics can be gained from the temperature dependence of the ethanol profile observed in solution. By applying a theoretical consideration used in NMR spectrometry to explain the dependence of the spectra on molecular dynamics to the present problem on vibrational spectrometry, the following values of the trans ⇌ gauche transition rate are determined: (3.6 ± 0.6) · 1010 s−1 at 20°C and (9.0 ± 1.5) · 1010 s−1 at 137°C.
Temperature and Viscosity Effects on an Excited State Equilibrium as Revealed from the Dual Fluorescence of Very Dilute Solutions of 1‐Dimethylamino‐4‐cyanonaphthalene
Authors: Ayuk Atu Ausaji , Rettig W. , Lippert E. 
Published: July 2012

AbstractIt is shown that polar solutions of 1‐dimethylamino‐4‐cyanonaphthalene display dual fluorescence, closely related to that of p‐dimethylaminobenzonitrile. — The kinetic model introduced by Grabowski et al. has been used. This involves a temperature dependent excited state equilibrium, B → A, which is responsible for the characteristic maximum observed for the fluorescence quantum yield ratio ϕA/ϕB as a function of temperature. — With the help of the degree of polarization of the short wavelength fluorescence band, FB, as a function of temperature, an inversion of the 1La and 1Lb fluorescent states is shown to occur in propylene glycol at room temperature. This fluorescence level inversion is assumed to arise from reorientation effects of the solvent molecules. — The long wavelength fluorescence band, FA, is emitted from a third state which is formed via an adiabatic photoreaction along a reaction coordinate involving solvent reorientation as well as solute geometrical relaxation (intramolecular twisting).
Formation and Fate of NH(X3Σ−) in the Pulsed Vacuum UV Photolysis of NH3
Authors: Zetzsch C. , Stuhl F. 
Published: July 2012

AbstractThe formation of NH(X3Σ‐) from the pulsed vacuum uv photolysis (λ > 105 nm) of NH3 was investigated. Using resonance fluorescence detection the kinetics of NH was studied at room temperature. NH could be observed for up to 2 s; the efficiency of removal of NH by collisions with the walls of the reactor is estimated to be of the order of 10−4. A reaction of NH with its parent molecule NH3 or with N2 was not detected. Upper limits for the rate constants of the reactions magnified image.
Analyses of Vibrational Progressions in Luminescence Spectra of Platinum‐Group d6Complexes
Authors: Eyring Gerd , Schmidtke Hans‐Herbert 
Published: July 2012

AbstractLow temperature (10 K) luminescence spectra of powder samples and single crystals of various Rh(III), Ir(III), and Pt(IV) complexes have been recorded. Some of these show vibrational fine structure which is explained by several progressions arising from different promoting modes. Band analyses carried out by decomposing the emission profile into a series of lorentzian or gaussian distributions lead to accepting mode frequencies which match frequencies in vibrational spectra. By comparing intensity distributions in the progressions with theoretical line shape functions from recent vibronic theories, some optical and geometrical parameters pertaining to the excited electronic states (potential minima shifts, changes in oscillator frequencies with respect to the ground state) have been calculated. For this analysis the quality of the vibrational resolution is of importance. Broad band vibronic spectra which cannot be resolved at low temperature can also be used to a certain degree for determining excited state properties. The results obtained from simple models seem to agree well with the data obtained from the narrow line spectra.
High Pressure O‐17 Longitudinal Relaxation Time Studies in Supercooled H2O and D2O
Authors: Lang E. W. , Lüdemann H. ‐D. 
Published: July 2012

AbstractThe spin‐lattice relaxation times T1 of the oxygen‐17 isotope in light and heavy water have been measured at 13.56 MHz in the temperature range 457 K to 238 K and up to pressures of 250 MPa. Below 300 K all isotherms exhibit maxima of T1 which become most pronounced at the lowest temperatures measured. A marked isotope effect is seen in going from light to heavy water. The ratio [T1(H217O)/T1 (D217O)]T,p is temperature dependent and increases with decreasing temperature. Furthermore the isotherms in D2 17O exhibit a stronger pressure dependence than the isotherms in H2 17O. The correlation times τθ derived from 2H‐T1 and 17O‐T1 in heavy water are identical at all pressures and temperatures and demonstrate the isotropic nature of the orientational fluctuations of the molecules in liquid water. The temperature dependence of τθ can at low pressures (p < 150 MPa) be described by a fractional power law with a singular temperature Ts, whereas at high pressure (p > 150 MPa) the isobars can only be fitted by the VTF‐equation with the ideal glass transition temperature T0. Ts as well as T0 are found to be higher in heavy water compared to light water.
Laser‐Blitzlichtphotolytische Untersuchungen zur Druckabhängigkeit der Reaktion ClO + NO2 + N2 → ClONO2 + N2
Authors: Dasch W. , Sternberg K.‐H. , Schindler R. N. 
Published: July 2012

AbstractThe kinetics of the reaction ClO + NO2 + N2 → ClONO2 + N2 was investigated at room temperature in the pressure range 28 < p < 824 mbar by ClO‐absorption measurements. As source for ClO radicals Cl2O was used. The reaction was initiated using monochromatic light pulses from a KrF*‐excimer laser at λ = 248.5 nm. A Xe‐high pressure lamp and a pulsed Mg‐hollow cathode lamp respectively were used as analytic light sources. The atomic emission of the hollow cathode source at λ = 285.2 nm coincides with the 8. vibrational state of the ClO absorption. The results are discussed and compared with data obtained in other experimental studies as well as in model calculations.
Interaction of CFCl3 with an Fe(100) Surface Part I: Adsorption and X‐Ray Induced Effects at 90 K
Authors: Dowben P. A. , Grunze M. 
Published: July 2012

AbstractWe studied the interaction of CFCl3 with an Fe(100) surface over a temperature range from 90‐700 K using surface sensitive techniques. In the first part of our communication we describe adsorption at temperatures below 300 K. Initial adsorption on the clean Fe(100) surface at 90 K is dissociative and is followed by molecular adsorption up to 6 molecular monolayers. Multilayer formation is not expected from the heat of condensation of CFCl3. The adsorption of molecular layers therefore indicates a long‐range stabilization by the substrate of the adsorbate phase. This observation is of general significance of the understanding of extrinsic precursor states in adsorption. We further observe X‐ray induced processes in the adsorbed layer which can be distinguished from thermally induced dissociation.
ESR Studies on the Interaction of Molecular/Atomic Oxygen and Ethylene with Silver Zeolites
Authors: Hermerschmidt D. , Haul R. 
Published: July 2012

AbstractParamagnetic Ag2+ centres are formed by interaction of O atoms with dehydrated AgA and AgX as studied by in situ ESR measurements in a flow system. Interaction of molecular oxygen with the reduced, silver loaded zeolites leads to O−2 adsorbed on an “oxidized” surface. No indication for adsorbed O− was found. The conduction electron ESR signal of small Ag particles serves as a probe for chemisorption of O2 C2H4, C2H4O and H2O; it is not affected by CO2. – Reaction of C2H4 with Ag2+ results in a radical, while no paramagnetic intermediate is detectable in the immediate reaction with O2−.
Temperature and Hydrogen Concentration Measurements by CARS in an Ethylene‐Air Bunsen Flame
Authors: Müller‐Dethlefs K. , Pealat M. , Taran J.‐P. E. 
Published: July 2012

AbstractLocal temperatures and hydrogen concentrations in an ethylene‐air Bunsen flame have been determined from CARS measurements of the Q(0) to Q(4) [υ = 1 ← υ = 0] Raman transitions in hydrogen. A crossed beam, BOXCARS, technique of high spatial resolution including non‐resonant background cancellation is employed. The linewidth correction is taken into account for the limit of Doppler broadening. The results agree well with thermodynamic equilibrium calculations.
Temperature Dependence of the Chemiluminescent Reaction (1), NO + O3 → NO2(2A1; 2B1,2) + O2, and Quenching of the Excited Product
Authors: Schurath U. , Lippmann H. H. , Jesser Barbara 
Published: July 2012

AbstractThe title reaction (1) was studied at very low total pressures. The activation energy of the chemiluminescent pathway (1a) depends on the wavelength range in which emission is detected. Measurements at 1.27 μ, close to the maximum of the emission spectrum, yield 16.2 kJ mol−1 which presumably equals the activation energy E1a of the chemiluminescence integrated over all wavelengths. The absolute quantum yield at 290 K was determined to be k1a/k1 = 0.20, using the infrared atmospheric band emitted by known concentrations of O2(1Δg) as intensity standard. These results are combined with temperature dependent rate constants of the bulk reaction to yield separate Arrhenius equations, k1a = 2.90 · 10−12 exp(‐1951 K/T) cm3 s−1 for the electronically excited product, and k1b = 2.27 · 10−12 exp(‐1475 K/T) cm3 s−1 for the dark component of reaction (1). The half‐quenching densities of the chemiluminescence were found to be both wavelength‐ and temperature dependent, following approximately a T0.5 dependence for M = N2.
Statistical Treatment of Data of Excess Chemical Potential of Organic Binary Mixtures
Authors: Gioia Lobbia G. , Vitali G. , Berchiesi M. A. , Berchiesi G. 
Published: July 2012

AbstractThe liquid‐solid equilibrium temperatures of organic binary mixtures are treated in order to have the excess chemical potential. This thermodynamic quantity is statistically treated following the groups interaction theory and the interchange parametres are derivated.
The Independent Molecular Interaction Sites Model I. A New Reference System for the Thermodynamic Perturbation Theory of Molecular Fluids
Authors: Naumann Karl‐Heinz , Lippert Ernst 
Published: July 2012

AbstractA new reference system for the treatment of molecular fluids within the framework of thermodynamic perturbation theory is presented. The basic ingredient of our approach is a potential transformation which allows us to view molecular liquids and gases as mixtures of formally independent molecular interaction sites (IMIS model). Some relations between our method and the RAM theory are discussed.
Homogene Kondensation von übersättigtem Eisendampf. Kinetische Untersuchungen mit einem Stoßwellenrohr
Authors: Steinwandel J. , Dietz Th. , Joos V. , Hauser M. 
Published: July 2012

AbstractIron vapor was produced by unimolecular decomposition of Fe(CO)5 in the front of a planar shock wave giving supersaturation in a wide range. The condensation of these systems has been detected by time resolved absorption spectroscopy using the collision broadened Fe I‐Resonance line 385.991 nm. The initially produced atomic iron densities were 2 to 5.1014cm−3 in the temperature range between 1700 and 1000 K; the degree of supersaturation is 2 ≤ In p/p∞ ≤ 20. ‐ A pre‐equilibrium with condensation, according to classical nucleation theory, can be excluded within experimental limits of accuracy, even if supersaturation is low.
Solid State Chemical Model for the Solubility Behaviour of CaCO3  MgCO3 Solid Solutions
Authors: Driessens F. C. M. , Verbeeck R. M. H. 
Published: July 2012

AbstractMg‐calcite can contain up to about 6 mol‐% MgCO3, dolomite between 40 and 51%. Solid solutions of CaCO3 and MgCO3 are unstable between 20 and 30 mol‐% MgCO3. The thermodynamic stability of dolomite with respect to calcite and magnesite amounts to about ‐6.8 kJ mol−1. It is shown that both the thermodynamical properties and the solubility behaviour of these solids can be explained with a solid‐state chemical model based on the theory of subregular solid solutions. Evaluation of the parameters of the model resulted in a critical cluster size of about one unit cell for the dolomite structure. The fact that normal sea water is close to equilibrium with both calcite and dolomite means that the concentrations of Ca2+, Mg2+ and CO32‐ ions in sea water are restricted by fixed sclubility relations.
Investigation of Electron Transfer Reactions of Metal‐Porphyrin Complexes in Micellar Solutions
Authors: Eck V. , Marcus M. , Stange G. , Westerhausen J. , Holzwarth J. F. 
Published: July 2012

AbstractWe have used the “Stopped‐Flow”‐ and the “Continuous Flow”‐methods to investigate the electron‐transfer behaviour of silver‐porphyrin complexes in aqueous and micelle containing solutions. Using IrCl62‐or Os(dipy)33+as the electron acceptor compound and silver(II) complexes of tetraphenylporphyrin tetrasulfonic acid (TPPTS), protoporphyrin (PP) or mesoporphyrin (MP) as the electron donor, second‐order rate constants between 104M−1s−1and 1010M−1s−1could be measured.—In aqueous solutions all three porphyrin complexes showed a complex kinetic behaviour because of dimerisation or the formation of higher aggregates. Only Ag(II)TPPTS was monomeric at low ionic strength.—In the presence of surface active substances such as sodiumdodecylsulfate (SDS), dodecyltrimethylammonium chloride (DTAC) or cetyltrimethylammonium chloride (CTAC) in concentrations above the cmc, where micelles are formed, all silver‐porphyrin complexes could be incorporated as monomers into the hydrophobic core of the micelles. In this way it was possible to investigate the kinetics of electron‐transfer of monomeric porphyrin complexes and to compare these with the behaviour in aqueous surfactant‐free solutions. Special attention was paid to measuring the activation barrier for an electron‐transfer from porphyrin complexes in the hydrophobic part of the micelles to redox ions in the surrounding solution. By varying the ionic strength of the solution and adding different types of surfactants, pure electrostatic effects could be separated from barriers which are created by an electron‐transfer through the surface of the micelles.—The mechanisms of these reactions are explained quantitatively to demonstrate the possibilities of influencing such electron‐transfer reactions.
Elektronenmikroskopische Untersuchungen von Mizellen
Authors: Bachmann L. , Dasch W. , Kutter P. 
Published: July 2012

AbstractAqueous micellar solutions of the following surfactants were freeze‐etched and investigated by electron microscopy: eicosyl‐ and docosylsulfate, docosyl‐pyridiniumbromide, hexadecyl‐N‐glycine, sucrose‐monomyristate and ‐palmitate. Micellar weight, aggregation number and critical micellar concentration can be determined by counting the number of micelles per area. Within the investigated range (up to 20 times the cmc) the aggregation number is not influenced by the concentration of the surfactant. The data obtained by electron microscopy are in accordance with those found in the literature.—The size and the shape of the micelles were measured with a particle size analyser. All micelles appeared spherical with a diameter of more than 8 nm. Even if the particles appear too large due to the preparation techniques, the real diameter of the hydrated micelles should always be larger than 6 nm.—This technique is particularly good for the investigation of surfactants with a very low cmc (≤ 10−5 molar) in saltfree solutions. Its most interesting aspect is the investigation of systems containing particles of various sizes and shapes.