bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure Dependence of Resonant Intermolecular Vibrational Coupling etc.in Isotropic Raman Scattering of the v2 Mode of CH3I
Authors: Döge G. , Lindner D. 
Published: July 2012

AbstractThe pressure dependence of the isotopic dilution effect on the Raman band of the v2 mode of CH3I and CD3I has been investigated. In this way the resonant intermolecular vibrational coupling term has been separated from the other vibrational relaxation terms. It could be shown that the density dependence of this term is stronger then it is predicted from recent theories. The possible reasons for the discrepancy are discussed. The pressure dependence of a dynamical parameter τΩ is also obtained from the vibrational relaxation functions.
Strong Thermal Lens Induced by Laser Light in the Mixtures of Organic Liquids with Ferrocene
Authors: Kruk G. , Gburski Z. 
Published: July 2012

AbstractThermally induced changes in the refractive index of liquid benzene and ethyl alcohol, illuminated by the blue argon ion laser beam, were studied. The development of a thermal lens and strong increasing (factor of ten) of the defocusing angle of the incident laser beam. was observed for the liquids mixed with ferrocene.
Amplitude Ratios for Viscosity & Thermal Conductivity Anomalies Near a UCST
Authors: Maczek A. O. S. , Davies M. K. , Jayasuriya J. E. C. 
Published: July 2012

AbstractAmplitudes of power laws which describe the viscosity of binary liquid mixtures in the close neighbourhood of a critical solution temperature were determined along the coexistence curve and along the critical isochore for a number of different systems. Dynamic renormalisation group theory predicts that the ratio of amplitudes along these two paths should be a universal constant, with a value of 0.950, for every binary system close to a critical point. If the amplitudes are determined by fitting the experimental viscosity data to a power law in which the critical exponent is treated as a disposable variable, the resulting ratios vary from about 0.94 to 0.97. If corrections for shear gradient dependence of the viscosity close to a critical point are made and the critical exponent is fixed at the value χλ = 0.040 predicted by dynamic renormalisation group theory, then all the systems considered show amplitude ratios which converge to 0.950 ± 0.001, in excellent agreement with theory. A similar analysis of results for the thermal conductivity anomaly detected in the system perfluoromethylcyclohexane + methylcyclohexane shows that, to within experimental error, the predicted amplitude ratio of 0.473 for thermal conductivity is compatible with the experimental data. Amplitude ratios for these transport properties appear indeed to be universal constants, as dynamic renormalisation group theory predicts.
Pressure‐jump Experiments for the Study of the Kinetics of Phase Separation in the Binary System Ethene/Hexane. I. Transient Light Scattering Measurements
Authors: Metz U. , Schneider G. M. 
Published: July 2012

AbstractMeasurements were performed with ethene/hexane mixtures at pressures up to 8 MPa and at temperatures from 293 to 323 K in order to study the process of demixing of a gas/liquid system. Supersaturation was achieved by a pressure jump technique that makes possible differential pressure jumps from 0.05 up to 1 MPa into metastable regions of the miscibility gap in less than 5 ms. ‐ The appearance of the new phase within the liquid mixture was observed by means of light scattering. Transient light scattering measurements at an angle of 90° were carried out in order to determine the kinetic limit of bubble growth following homogeneous nucleation along the phase boundary of the binary liquid with respect to a p(x) isotherm as well as to a T(x) isobar. It will be shown that the primary limitation of our light scattering measurements is the appearance of multiple scattering.
A Theoretical Study of the Time‐Dependence of Solvent Diffusion in a Polymer
Authors: Rudolph Franz , Peschel Gerhard 
Published: July 2012

AbstractBased on experimental evidence in literature an attempt is made to theoretically derive an expression for the diffusion rate of a solvent in a polymer, a process by which the polymer can adopt a gellous state. In particular the movement of the solvent/gel interface is examined. With respect to the time dependence the solvent diffusion in polymers can be attributed to two cases

Proportional to t (Alfrey's Case I)
Proportional to √t (Alfrey's Case II)
Both cases are mathematically treated particularly with respect to the different time‐dependence of solvent diffusion.
Time Resolved Observation of Nascent OH Rovibronic Distribution and Benzyl Radicals Formed in the Infrared Multiphoton Dissociation of Benzyl Alcohol
Authors: Chowdhury P. K. 
Published: July 2012

AbstractThe infrared multiphoton dissociation (IRMPD) of benzyl alcohol (BENZAL) generates OH and benzyl radicals as the primary products. The IRMPD yield of benzyl alcohol shows a strong fluence dependence, with a threshold of 6 J cm−2 for the 10 R(30) CO2 laser line at 982 cm−1. The nascent OH fragments are probed via laser induced fluorescence (LIF) under collisionless conditions, to determine the initial product state distributions. There is no significant population ( <2%) in the excited vibrational level of OH (X2II). However, the initial rotational state distribution is Boltzmann‐like, characterized by a rotational temperature of about Trot = 1100 K. The time dependent measurement of OH by LIF is used to derive an average internal energy of BENZAL above its threshold dissociation, at CO2 laser fluences of 7‐11 J cm−2. The benzyl radical is also monitored by LIF in its 12A2←12B2 band system and is found to be produced vibrationally “hot”. About 500 collisions with argon are required for its thermalization.
Multilayer Adsorption of Nitrogen
Authors: Guil J. M. , Herrero J. E. , Noguerales P. , Masiá A. Pérez , Ruiz Paniego A. 
Published: July 2012

AbstractA multilayer adsorption model previously developed in this laboratory has been applied to the adsorption of nitrogen at 77 K on eighteen samples: eight oxides, nine scheelites and a sample of cadmium chloride. The applicability range of the model begins at coverages close to the monolayer capacity, with an upper limit imposed by capillary condensation, if it exists. Surface heterogeneity is accounted for through an exponential distribution function of the adsorption sites, whose two parameters are calculated from the model equations; one of them gives the lowest energy of the adsorption sites and is related to the adsorption enthalpy; the other one governs the shape of the distribution curve and is related to surface heterogeneity. The equations yield also the exponent governing the variation of the interaction energy of the molecule with the distance to the surface, whose values for most of the samples are near 3, pointing to an interaction arising from London dispersion forces. The application of the model is not successful in a few cases, probably due to the inadequacy of the assumed exponential function to describe the surface energy distribution.
Solvation of Ions in Acetonitrile‐Methanol Solutions of Sodium Iodide
Authors: Hawlicka E. , Grabowski R. 
Published: July 2012

AbstractThe self‐diffusion coefficients of acetonitrile, methanol and ions in salt free acetonitrile‐methanol mixtures and in solutions of NaI have been measured at 25°C for the whole composition range of the binary solvent, for the salt molarity ranging from 1 · 10−4 to 1 · 10−2. The limiting self‐diffusion coefficients of sodium and iodide ions increase monotonously with increasing concentration of acetonitrile. The composition dependences of the ionic radii allow to postulate a preferential solvation of iodide ions by acetonitrile. That phenomenon has been found for those compositions of the mixed solvent, for which a microheterogeneity of the system has been observed. In methanol rich solvents (xAN < 0.5) the observed microheterogeneity results from the self‐association of methanol. The preferential solvation of iodide ions causes an enlargement of acetonitrile aggregates resulting in enhancement of microheterogeneity of the system. These results confirm a hypothesis that if interactions between ions and components of the mixed solvent are similar the preferential solvation of ions is promoted by the structure of solvent.
Chevrel Phase Type Compounds: Electronic, Chemical and Structural Factors in Oxygen Reduction Electrocatalysis
Authors: Jaegermann W. , Pettenkofer C. , Alonso Vante N. , Schwarzlose Th. , Tributsch H. 
Published: July 2012

AbstractChevrel type chalcogenides of stoichiometry Mo6Se8 and (Mo6‐Mx)MxSe8 (with Mx = Ru2; Re4) are investigated as electrocatalysts for the reduction of molecular oxygen in acidic medium. The catalytic activity is related to the surface corrosion tendency as investigated with XPS. The Ru‐cluster proved to be more stable to air oxidation than the Re and Mo cluster compounds. Only small amounts of oxidation products are found for all samples exposed to the electrolyte in the range of the oxygen reduction potential. At more positive bias with respect to the open circuit potential anodic corrosion currents are observed for all compounds which are due to formation of metal oxides. — The reactivity of the clusters seems to be associated to the electronic structure which was obtained from XPS and UPS measurements. In all cases the band edges are derived from metal d‐states which are hybridized with chalcogenide p‐states. The catalytic activity is discussed in terms of possible surface interactions which are determined by the electronic nature of the band edge states.
Determination of the Thermodynamic Properties of Liquid Methanol from 203 to 263 K and up to 280 MPa from Speed of Sound Measurements
Authors: Sun T. F. , Schouten J. A. , Biswas S. N. 
Published: July 2012

AbstractThe sound speed in liquid methanol has been measured up to 280 MPa and in the temperature range between 203 K and 263 K, using a phase comparison pulse‐echo technique operating at 2 MHz. The density, isothermal compressibility, isobaric thermal expansion and the specific heat have been evaluated from the measured sound speed, together with the density and specific heat at 0.1 MPa. A modified computational method originally developed by Davis and Gordon was used. The derived density data have been used to examine the validity of several empirical equations of state.
Investigations on the Kinetics of the Anodic Intercalation Process of Graphite in 65% HNO3 by Using AC Impedance Measurements
Authors: Scharff P. , Stumpp E. , Barteczko K. , Xu Z.‐Y. 
Published: July 2012

AbstractThe electrochemical properties of the interface between graphite sample and electrolyte solution will change during the anodic intercalation process. The physical quantities which indicate these electrochemical properties can be calculated from the results of the AC impedance measurements. An equivalent circuit is suggested for the calculation. The results of this method are in very good agreement with those from other methods, therefore it is very helpful for studying the kinetics of the anodic intercalation process into graphite in the electrolyte solution.
The Refractive Index of Perfluorinated Surfactant Solutions
Authors: Pößnecker Gerhard , Hoffman Heinz 
Published: July 2012

AbstractThe refractive index of several perfluorinated surfactant solutions was measured as a function of the concentration. The plot of the refractive index against the concentration for each surfactant shows a sharp break at the cmc. For several systems the slope of the refractive index changed even its sign. The extent of this change is much bigger for perfluorinated surfactants than the change that is shown by hydrocarbon surfactants. It is shown by density measurements that the difference of the refractive index increment above and below the cmc is due to the difference of the partial molar volumes of the surfactant molecules in the monomer and in the micellar state. It is thus possible to determine volume changes in surfactant systems by means of the measurement of the refractive index.
Parametrization of 4f – 4f Transition Probabilities of Eu3+ Ions in Na5Eu(MoO4)4 and Na5Eu(WO4)4
Authors: Hølsä Jorma , Porcher Pierre , Huang Jinggen 
Published: July 2012

AbstractThe simulation of the 4f—4f electric and magnetic dipole transition probabilities of Eu3+ ions in Na5Eu(MO4)4 (M = Mo and W) was carried out according to the Judd‐Ofelt theory. The experimental data consist of 29 5D0,1 → 7FJM transitions between crystal field sublevels. — The optimization of the six non‐zero Bλkg parameters allowed for the D2d symmetry yielded the following sets for Na5Eu(MoO4)4 and Na5Eu(WO4)4 (in 10−10 cm units). B232 = ‐2.01 (‐1.94), B432 = 0.66 (0.57), B452 = 3.31 (3.07), B652 = 8.47 (6.72), B672 = 2.27 (2.63) and B676 = 31.11 (30.93), respectively. These sets give reasonable simulation to the experimental transition probabilities. The conventional Judd‐Ofelt theory was, however, unable to simulate the intensity of the “hypersensitive” 5D0 → 7F2 transition. Most of the discrepancies are due to the uncertainty in experimental data although the influence of basis set truncation (only 671 |LJM> levels out of the total of 3003 were included in the basis set of wave functions) and the approximate symmetry (D2d symmetry was used instead of the real S4 one) cannot be neglected, either.
Investigation of Nickel Plating by Photoacoustic Spectroscopy (PAS) and Scanning Tunneling Microscopy (STM)
Authors: Yoshihara Sachio , Sato Ei‐ichi , Fujishima Akira 
Published: July 2012

AbstractPhotoacoustic technique was employed to study the plating of Nickel. And on the other hand, Scanning Tunneling Microscopy (STM) cleared the difference of the surface in the presence and in the absence of the brightener. Also Scanning Electron Microscopy (SEM) was used for supporting the data of STM.
The Importance of Metastable RNA Folding in Biological Regulation and Control
Authors: Fernández Ariel 
Published: July 2012

AbstractWe explain the radical difference in pause site patterns during the synthesis of MDV‐1 RNA, depending on the nature of the process involved. The two situations of interest are: a) Replication by Qβ‐replicase, a template‐instructed synthesis b) Transcription performed by E. Coli RNA polymerase. The starting point is an extended mode analysis of the backbone soliton‐like dynamics. These solitary waves induce a tautomerization of uracil which occurs exclusively in transcription with a definite probability. This tautomeric form of uracil forms base‐pairing with guanine and leads to a unique metastable folding of RNA. The assessment of this fact enables us to prove that in both replication and transcription, the pauses in the process are due to refolding events occurring in the replica chain as it is being synthesized and in the upstream portion of the template strand.
Kinetics and HO2 Product Yield of the Reaction C2H5O + O2 between 295 and 411 K
Authors: Hartmann D. , Karthäuser J. , Sawerysyn J. P. , Zellner R. 
Published: July 2012

AbstractThe kinetics of the reaction between ethoxy (C2H5O) radicals and O2 have been studied using a combined laser photolysis/LIF technique for the generation and detection of C2H5O. In the temperature range 295–411 K the rate coefficient has been found to be
equation image
.Product investigations using a chemical titration of HO2 by NO and subsequent quantitative detection of OH by LIF indicate the dominance of the HO2 formation channel, viz.
equation image
with ϕ = 0.89 (−0.12+0.22). Energy correlations show that these products are formed by a direct metathesis reaction only. It is suggested, that the low pre‐exponential factor in the Arrhenius expression may be the result of a more complex than linear configuration of the moiety in the transition state and/or of tunneling.
2‐Butanol‐Water System in the Presence of Sodium Chloride and Potassium Chloride
Authors: Apelblat Alexander , Manzurola Emanuel 
Published: July 2012

AbstractPartition of 2‐butanol, water, NaCl and KCl between the aqueous and alcoholic phases at 298.15 K is considered. Extraction of chlorides is represented as a formation of partially dissociated complexes in the alcoholic phase. The equilibrium constant for formation of the Na+(2‐BuOH)2Cl− complex is 0.11 and for formation of the K+(2‐BuOH)2Cl− complex is 0.16. Detailed thermodynamic analysis of the investigated systems is presented by evaluating activities of components from the mass‐action and Gibbs‐Duhem equations.
Kinetics of the Oxidative Silver Chloride Formation on Silver with CoIII(NH3)5Cl3 Studied by Galvanostatic Reduction of the Chemically Formed Silver Halide
Authors: Nickel U. , Haase E. , Liu C.‐Y. 
Published: July 2012

AbstractSilver chloride was formed on a rotating silver disc electrode by oxidation with [CoIII(NH3)5Cl]2+ in acid solution and subsequently reduced galvanostatically in order to determine quantitatively the amount of silver(I) formed during the chemical oxidation. By varying both the oxidation time and the concentration of the cobalt complex as well as that of chloride the kinetics of the formation of silver chloride was studied indirectly. As long as the concentration of chloride exceeds that of the cobalt(III) complex the reaction is first order in [CoIII(NH3)5Cl]2+ and almost zero order in Cl−. The diffusion controlled process can be explained with the theory of mixture potential and mixture current and may therefore be regarded as a corrosion process.
Diffusion Coefficients in Systems with Inclusion Compounds. Part 2. α‐Cyclodextrin‐(DL)Norleucine‐Water at 25°C
Authors: Paduano Luigi , Sartorio Roberto , Vitagtiano Vincenzo , Costantino Lucia 
Published: July 2012

AbstractDiffusion coefficients in the ternary system α‐cyclodextrin (at one concentration)‐(DL)norleucine (at three concentrations)‐water have been measured using the Gouy interferometric technique. — The effect of the inclusion equilibrium on the cross‐term diffusion coefficients was observed. — The measured diffusion coefficients in the ternary systems were used to calculate values of the binding constant. These values are in good agreement with that obtained from calorimetric studies.
Density and Dielectric Polarizability of n‐Alkane Liquids
Authors: Scaife W. G. , Lyons C. G. 
Published: July 2012

AbstractParameters for a form of the Tait equation which includes temperature, are given for n‐alkanes from n‐pentane to n‐decane. Taken with published data for dielectric polarizability, values of volume occupied per molecule Vm, and polarizability α per molecule have been computed at different pressures and temperatures. By plotting Vm and α as functions of carbon number a comparison can be made among these liquids and with other literature data. Density trends at the approach to boiling can be discerned.
The Static Dielectric Constant and Density of t‐Butyl Chloride to 200°C and 2000 bar
Authors: Vani V. C. , Michelberger Th. , Franck E. U. 
Published: July 2012

AbstractThe relative static dielectric constant or permittivity ϱ and density ρ of t‐butyl chloride was measured between 25°C and 200°C and from 100 to 2000 bar. The high pressure cell, simultaneously applicable to determine ε and ϱ, is described. Sample densities range from 0.694 to 0.949 g · cm−3. At 25°C and from 100 to 600 bar ε increases from 9.86 to 10.59. At 100°C between 100 and 2000 bar ε ranges from 6.75 to 8.57. At 200°C from 200 to 2000 bar ε grows from 4.12 to 5.69. Functions for ε and ρ in dependence of pressure with fitted parameters are given. Calculated Kirkwood correlation factors g are presented, which exceed unity only moderately (from 1.03 to 1.22). A comparison is made with ε‐values of high pressure HCl and CH3Cl.
Theoretical Prediction of the Primary Sequence for an RNA Species Fitted for Replication by Qß‐Replicase
Authors: Fernández Ariel 
Published: July 2012

AbstractWe predict the melting profile for a globular (folded) stable state of MDV‐1RNA. We search for sequences realizing those features in the melting profile which are sequence‐dependent. The search is subject to three constraints: a) Intra‐chain folding should be favored over double‐strand formation; b) At least one stable hairpin should occur every 35 nucleotides so that the RNA species can fulfill the regulatory function throughout replication; c) The subsequence for internal recognition by Qß‐replicase and the primers should be fixed at particular positions in the sequence. These constraints have enabled us to predict the full sequence of MDV‐1RNA, a naturally‐occurring template of Qß‐replicase.
Influence of the Phase Structure on the Gas Transport Behaviour Through Liquid Crystalline Side Chain Elastomer Membranes
Authors: Modler H. , Finkelmann H. 
Published: July 2012

AbstractThe dependence of hydrocarbon gas transport behaviour on the liquid crystalline (LC) and isotropic state of different liquid crystalline side chain elastometer membranes (LCSCE‐membranes) is investigated with respect to the LC‐phase structure of the membranes and the molecular shape of the gas molecules.—A distinct change of the transport behaviour at the phase transformation from the smectic to the nematic and from the nematic to the isotropic state is observed. Additionally, an odd‐even effect is detected determined by the spacer length of the mesogenic moieties at a temperature range a little above the phase transformation temperature from the LC‐ to the isotropic state. It is assumed that this odd‐even effect correlates with the stress temperature dependence of the LCSCE‐samples. An enhanced selectivity for linear shaped gases compared to spherical shaped gases occurs in a macroscopic ordered sample.—For these experiments the accuracy of the transport coefficient determination by a transport process through membranes is analysed with respect to the geometrical arrangement of the developed experimental apparatus. The experimental method of determing transport coefficients, already described by R. A. Pasternack, is discussed and further developed.—The LCSCE‐membranes are synthesized by adding a mesogenic side chain to a polymethylhydrogensiloxane network.
KrF Laser Induced Telomerization of Bromides with Olefins. Part 2: BrC2F4Br and BrC2F4C2H4Br with C2H4 and C2F4
Authors: Linyang Zhang , Buß W. , Kompa K. L. 
Published: July 2012

AbstractWe investigated the photochemical insertion of one to three olefin units into a CBr bond of two dibromides in gas phase. Unexpected high quantum yields (up to 30) were found in the system BrC2F4Br + C2H4 for the product BrC2F4C4H8C2F4Br and some others. Therefore they cannot be radical combination products, but must arise from chain propagation. To explain their formation, accumulation of C2F4 must be assumed. The addition of ethylene to a radical can be reversed by Br atoms. This reaction strongly influences the product spectrum. Synthesis of BrC2F4C4H8C2F8Br would be economic by the laser method. The preparation of BrC2H4C2F4C2H4Br was also much improved over previous methods.