bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic wetting on porous and non porous substrates. Influence of surface tension, viscosity and porosity
Authors: André V. , Zosel A. 
Published: July 2012

AbstractIn this work, we have studied the wetting behaviour of liquids on closed and non closed surfaces. Contact angle measurements were performed on polymer and glass surfaces (non porous, closed surfaces) and on calibrated glass filters (porous, non‐closed substrates). Silicone oils (polydimethylsiloxane) having different viscosities η1 (between 1 and 1000 Pas) and a low surface tension (γ1 = 21 mN/m) were used as well as liquids with a higher surface tension (solutions of polyisobutylene in decaline; γ1 = 31 mN/m and Polyacrylic Acid in water; γ1 = 66.3 mN/m) also covering a large range of viscosities.The contact angle measurements were done in the dynamic mode with the help of an image processing system and a CCD Camera. The modification of the contact angle could be recorded with a frequency of one picture per 66 ms. For the closed surfaces (polymer and glass), the volume of the deposited drop remains constant whereas it changes with time in case of a porous system. The image processor allows the acquisition of the contact angle (θ), of the drop volume (V/V0) and of the drop radius (r/R0), where V0 is the volume and R0 the radius of the original drop.The curves of cos θ and r/R0 vs time for the liquids can be superimposed in a master curve by plotting versus γ1·t/η1·R0 (also called reduced time). For the non porous substrates (glass, Polyethylenterephthalat, Polytetrafluoroethylen), the master curves coincide at small wetting times which means that the early stage of the wetting process is determined only by the properties of the wetting liquid. The influence of the surface tension was not clearly observed but the viscosity plays an important role at the beginning of the wetting process.The porous substrates (glass filters) were proved to have a different behaviour. The master curves could be obtained for cos θ vs reduced time and V/V0 vs reduced time for different porosity grade (15–40 μm compared to 40–100 μm) for the polyisobutylene solutions as well as for the silicon oils (polydimethylsiloxane). However there is no agreement between polydimethylsiloxane and polyacrylic acid since for comparable viscosities the master curve for PAA is being shifted by a factor of about 1000 to longer times. Thus, contrary to the closed surfaces, the surface tension seems to be a limiting factor for the liquid penetration rate.
Growth kinetics of Kr and Xe multilayers physisorbed on graphite
Authors: Mannebach H. , Knorr K. 
Published: July 2012

AbstractMultilayers of Kr and Xe physisorbed on graphite have been evaporated by intense laser pulses and the readsorption transients have been followed in time with an ellipsometer. The transients are discussed in reference to the equilibrium adsorption isotherms.
A grand isostress ensemble monte carlo study of thin films under shear
Authors: Schoen Martin , Diestler Dennis J. , Cushman John H. 
Published: July 2012

AbstractThin films of monatomic fluid constrained between two plane‐parallel structured solid walls have been simulated by Monte Carlo under conditions (fixed temperature, chemical potential and normal stress or load) prevailing in high‐precision measurements of surface forces. Several phases of the film (corresponding to different numbers of layers of fluid parallel with the walls) are generally consistent with these conditions, but only one is thermodynamically stable; the others are metastable. When the walls are properly aligned, epitaxial solidlike phases are stable. These melt under shear, eventually becoming metastable, whereupon a drainage (or imbibition) transition occurs, leading to a stable phase with fewer (or more) layers.
Hydrodynamics of a membrane bound to a substrate
Authors: Seifert Udo 
Published: July 2012

AbstractWe briefly review recent theoretical work on the dynamical equilibrium shape fluctuations of a membrane interacting with a substrate. Solving the hydrodynamical equations we determine the damping rate γ(q) as a function of the wave‐vector q. For small q, we find universally γ∼q2. In an intermediate q‐range, the damping rate behaves like either γ∼q6 (monotonic damping) or γ∼q2 (non‐monotonic damping) depending on the relative sizes of the mean separation and the parallel correlation length, which are both determined by the adhesion potential. For large q, one recovers the behavior γ∼q3 of a free membrane. A numerical solution of the dispersion relation is presented for a membrane subject to electrostatic repulsion in a linear attractive potential.
Complex fluids. Weakly to strongly structured mixtures
Authors: Kahlweit M. 
Published: July 2012

AbstractThis paper addresses the transition from weakly to strongly structured liquid mixtures of water, alkanes (Bk), and nonionic amphiphiles (CiEj). Starting with weak short‐chain amphiphiles, it is shown that the three‐phase bodies in such mixtures evolve from tricritical points (tcp) upon increasing either the carbon number k of Bk at fixed amphiphilicity (i,j) of CiEj, or upon increasing (i,j) at fixed k. In the first case, the three‐phase bodies grow monotonically with increasing distance from the tcp, whereas in the second case, they first grow, pass through a maximum in the range of medium‐chain amphiphiles, and shrink again as one proceeds to long‐chain amphiphiles. In that range in which the three‐phase bodies pass their maximum, one observes the gradual evolution of properties that distinguish weakly from strongly structured mixtures, such as the evolution of cmc surfaces, non‐wetting of the water/oil interface by the amphiphile‐rich middle phase, an o/w → w/o dispersion inversion near the mean temperature of the three‐phase body, and a correlation peak in the I(q) curves of SANS. This permits drawing a rather well defined border line between weakly and strongly structured mixtures in (i,j)–k space.
Bulk and interfacial properties of polar fluids
Authors: Frodl P. , Groh B. , Dietrich S. 
Published: July 2012

AbstractBased on a suitable density functional theory for inhomogeneous fluids we investigate both the bulk phase diagram and interfacial structures of polar fluids in general and of Stockmayer fluids in particular. We derive a scheme which allows us to analyze one‐component fluids composed of molecules with strong permanent dipole moments which are shown to affect significantly the bulk phase diagram. The results for the bulk phase diagram are in good agreement with published Monte Carlo data. Furthermore we investigate the profiles of the number density and of the orientational order at the liquid‐vapor interface as well as the corresponding surface tension. We systematically analyze the dependences of these quantities on the temperature and on the strength of the dipole moment of the molecules. This reveals power laws and, close to criticality, scaling behavior. Our approach, which is reliable even for large dipole moments, allows us to determine separately those contributions to the surface tension which are due to the orientational degrees of freedom.
Electric field‐induced structure changes in water‐in‐oil microemulsions: Time‐resolved Kerr effect measurements
Authors: Runge F. , Schlicht L. , Spilgies J.‐H. , Ilgenfritz G. 
Published: July 2012

AbstractA percolation transition in microemulsions can be induced by high electric fields. We report on the dynamics of the processes. Comparison of time‐resolved conductivity, birefringence and light scattering measurements gives information on the structure changes. The differences of ionic and nonionic microemulsions are emphasized.
In situ imaging of monolayers on interfaces by polarization and second‐harmonic microscopy
Authors: Flörsheimer M. , Jundt D. H. , Looser H. , Sutter K. , Küpfer M. , Günter P. 
Published: July 2012

AbstractA simple non‐scanning microscope for the in situ and real‐time investigation of many kinds of interfaces and ultrathin films is described. Polarization microscopy images the complex index of refraction of the sample, second‐harmonic microscopy images the second‐order optical susceptibility.
Quantum effects and orientational ordering in adsorbed layers of linear molecules
Authors: Marx D. , Sengupta S. , Nielaba P. 
Published: July 2012

AbstractWe study the influence of quantum fluctuations on the herringbone transition in adsorbed complete √3‐mono‐layers of diatomic molecules. Using Path‐Integral Monte Carlo simulations for rotations, we can quantify the shift of the transition temperature for a highly realistic model to describe N2 on graphite. In addition, the zero‐point motion of the librating molecules depresses the ground‐state order parameter. We compare the benchmark data to quadratic Feynman‐Hibbs effective potential simulations and to a quasiharmonic approximation. Using a simplified model for this transition, we study systematically quantum effects being relevant for lighter molecules. Depending on the rotator's rotational constant, we find re‐entrant orientational quantum melting or even the suppression of orientational order.
Mutual diffusion coefficients for the system benzene‐cyclohexene at 25 °C
Authors: Harris Kenneth R. , Dunlop Peter J. 
Published: July 2012

AbstractMutual diffusion coefficients are reported for mixtures of benzene and cyclohexene at 25 °C which have been measured using the Gouy interferometric technique. A comparison is made between this system and mixtures of benzene with perdeuteriobenzene, chlorobenzene and cyclohexane
Near‐infrared spectroscopic investigations on phase behaviour and hydrogen‐bonding of polar substances in supercritical chlorotrifluoromethane. Part II — association behaviour
Authors: Ochel Henning , Schneider Gerhard M. 
Published: July 2012

AbstractThe association behaviour of selected polar substances capable of self‐association in mixtures with supercritical chlorotrifluoromethane was investigated by high‐pressure near‐infrared spectroscopy. The alkanoic acids and cyclic amides investigated were dodecanoic acid, hexadecanoic acid, δ‐valerolactam, and δ‐caprolactam. The concentrations of the non‐associated molecules were determined from an evaluation of the first overtone region of O–H (∼ 1435 nm) or N–H stretching vibrations (∼ 1485 nm), respectively. The association behaviour is presented in plots of total, free, and hydrogen‐bonded molecule concentrations as a function of pressure. Furthermore, equilibrium constants Kc were determined and their density dependence is discussed, taking into account the influence of molecular properties on the association reaction in the supercritical fluid.
The relation of solvatochromism and thermochromism to the solvent dielectric constant: The basis of the ET and E'T polarity scales
Authors: Streck Christof , Richert Ranko 
Published: July 2012

AbstractWe have measured the thermochromism of pyridinium‐N‐phenoxide betaine and its penta‐tert‐butyl substituted derivative dissolved in MTHF together with the solvent dielectric properties in order to relate polarity scales to the dielectric constants of the solvent. Both thermochromic and solvatochromic shifts of the absorption band of the dyes can be rationalized on the basis of the MSA theory for relating the solvation free energy to the static dielectric constant. Deviations between theory and experiment in the regime of higher viscosities can be attributed to changes in the offset between absorption maximum and electronic transition energy.
Electrotransport in ionic crystals: II. A dynamical model
Authors: Janek J. , Martin M. 
Published: July 2012

AbstractA microscopic model of electrotransport in semiconducting ionic crystals is described, which is based on electrostatically interacting hopping charge carriers (cation vacancies and electron holes). Formulating rate equations for the thermally activated motion of electronic and ionic defects in external fields allows for the calculation of stationary charge distributions. In the case of large differences in the mobilities of both defects an adiabatic approximation can be introduced which allows to separate the motion of electron holes and vacancies. The formal problem is identical to the solution of the Poisson‐Boltzmann equation for large defect concentrations. An expression for the charge of transport is derived which is equivalent to the Debye‐Huckel expression for the relaxation effect but includes distinct geometrical positions around a central point charge.
Changes of vibrational modes upon melting mercury (II) halides
Authors: Voyiatzis G. A. , Papatheodorou G. N. 
Published: July 2012

AbstractRaman spectra of the “molecular” polycrystalline solids HgCl2 (D), HgBr2 (C) and of the yellow form of HgI2 (C) were measured from LN2 up to premelting temperatures. Polarized Raman spectra of molten HgX2 (X = Cl, Br, I) were measured at temperatures up to 950 K. The pure rotational band contour and the vibrational rotational contour of the HgX2 vapors were also measured. Upon melting the vibrational modes of the high temperature solid appear to be preserved. The spectra of the three liquids are similar and are best correlated to the spectra of the D (HgCl2) solid and the vibrational modes of the HgX2 molecules. Reduced Raman spectra of the liquids show splitting of the stretching mode to a doublet, ν1 (A1) and ν1 (B2g), which is attributed to strong intermolecular coupling. The ν2 and ν3 internal modes of the solid are also transferred into the melt. The predominant features of the low frequency reduced spectra is a band, VR, which is assigned to the rotatory modes of the HgX2 molecules and can be correlated to both the rotational band contour of the vapor and the librational modes of the solid. With increasing temperature the spectra of the liquid show softening of the rotatory modes and a blue shift of the ν1 mode, both implying weakening of the intermolecular coupling. An overall decrease in the Raman intensity of the liquid spectra with increasing temperature is attributed to the rapid molar volume increase.
Longitudinal relaxation rates of7Li in concentrated solutions of LiNO3in 1,3‐diaminopropane in the liquid state
Authors: Hayashi Hirokazif , Nakamura Yoshio , Shimokawa Shigezo 
Published: July 2012

AbstractThe temperature and concentration dependencies of7Li longitudinal relaxation have been investigated for concentrated solutions of LiNO3in 1,3‐diaminopropane in the liquid state. The experimental longitudinal relaxation rates (R1) of7Li are interpreted as the sum of the quadrupolar and the dipolar contributions. The dipolar contributions are estimated from the assumed local structure of solutions and the assumption that the correlation times of the quadrupolar and dipolar interactions are identical. Then, the quadrupolar contributions are separated from the experimentalR1, values and described by the electric field gradient (EFG) at the7Li nucleus and its reorientational correlation time (τ). The temperature dependence of τ deviated from a simple Arrhenius law over the temperature range studied. The composition dependence of τ and EFG show bends at around 30mol% LiNO3. This is consistent with the previous results obtained from the electrical conductance, and suggests that solvent molecules may act as bridges between Li+ions at higher concentrations of LiNO3.
Studies on the molecular motion of [M(daco)2]2+ Ions in bis‐daco complexes of MX2 (M = Cu(II) and Ni(II) and X = ClO4 or NO3; daco = 1,5‐diazacyclooctane)
Authors: Koner Subratanath , Ohki Hiroshi , Kikuchi Hikomitsu , Ikeda Ryuichi 
Published: July 2012

AbstractThe temperature dependence of the second moment (M2) of 1H NMR absorption of the partially deuterated (deuterated amine protons) complexes [M (daco‐d2)2] X2 · n D2O (M = Cu(II) and Ni(II); daco = 1,5‐diazacyclooctane; X = ClO4 or NO3; n = 0 for X = NO3 and n = 2 for X = ClO4) has been measured. Among them, [Cu(daco‐d2)2](NO3)2 showed a distinct drop in M2 at the same temperature region (ca. 363 K) where the complex is reported to undergo the thermochromic phase transition. The complexes [Cu(daco‐d2)2](ClO4)2·2D2O and [Ni(daco‐d2)2](ClO4)2·2D2O showed a gradual decrease of M2 around 220 and 280 k, respectively, without any colour changes and phase transitions, whilst M2 of [Ni(daco‐d2)2](NO3)2 shows no marked decrease with increase of temperature up to 400 K. M2 of rigid and motional lattices of [Cu(daco‐d2)2](NO3)2 is theoretically calculated using the reported X‐ray crystal structure data. The molecular motions of [Cu(daco‐d2)2](NO3)2, [Cu(daco‐d2)2](ClO4)2·2D2O and [Ni(daco‐d2)2](ClO4)2·2D2O are explained in terms of dynamic disorder of metal diamine chelate rings.
The electronic conduction mechanism of NiO‐crystals
Authors: Springhorn C. , Schmalzried H. 
Published: July 2012

AbstractElectrical conductivity measurements with the transition metal oxide (Ni,Fe)O have been conducted at T = 1573 K and T = 1525 K and under various oxygen potentials in order to decide which conduction mechanism prevails. Electron ‐ hole (polaron) hopping in the cation ‐ sublattice and (O2p)‐band conduction had been proposed before. The measured conduction buckle with a pronounced maximum suggests that polaron‐hopping is the prevailing conduction mechanism for (Ni1‐xFex)1‐δO.
Investigation of the CH3 + NO reaction in shock waves
Authors: Hennig G. , Wagner H. G. G. 
Published: July 2012

AbstractThe reaction of CH3 + NO was investigated behind incident shock waves at temperatures between 1300 K and 2080 K. The formation of H atoms and of HCN was studied by time resolved UV absorption and by IR‐emission. OH measurements of Hoffmann et al. were reevaluated with the rate constant of this work. The rate constant for the reaction of CH3 + NO can be expressed byk = (4.0 ± 0.8)·1012 exp (−(8500 ± 500) K/T) cm3 mol−1 s−1.HCN was found to be the main final product of the reaction of CH3 + NO in the temperature range covered. The contribution of the H forming channels is around 20–25% to the main channel.
Prediction of vapor‐liquid equilibrium data from excess enthalpy data for alkanol/alkane mixtures by the extended real associated solution model
Authors: Cabañas A. , Coto B. , Pando C. , Renuncio J. A. R. 
Published: July 2012

AbstractThe prediction of Vapor‐liquid Equilibrium data (VLE) from excess enthalpy data (HE) for alkanol/alkane mixtures by means of the Hanks‐Gupta‐Christensen (HGC) method is examined. The Extended Real Associated Solution model (ERAS) for the excess Gibbs energy which combines the Kretschmer‐Wiebe linear association model with Flory's equation of state for chainlike molecules is used. In this prediction, the parameters of the ERAS model are evaluated by fitting the experimental HE data to the algebraic equation for the HE of this model. Results from this study indicate that the ERAS model leads to VLE predictions which are more accurate than those previously obtained when the HGC method was used in conjunction with the Continuous Linear Association model or the Wiehe‐Bagley model.
Interfacial tension between water and non‐polar fluids up to 473 K and 2800 bar
Authors: Wiegand G. , Franck E. U. 
Published: July 2012

AbstractThe method of the Pendant Drop or Standing Bubble is applied to measure interfacial tensions between water and nonpolar fluids to high temperatures and pressures. The high pressure cell with two sapphire windows and the auxiliary equipment with several feed autoclaves is described. The shapes and sizes (about 2 mm) of drops and bubbles are recorded with microscope and video camera. A digital image processing procedure was developed which permits fast, objective and precise determination of the contour parameters.The six gases helium, neon, argon, nitrogen, methane, and propane have been investigated to 473 K (with nitrogen to 573 K) and (in part) to 2800 bar. Gas densities came close to liquid density values. For comparison, water plus liquid n‐hexane, n‐decane, and toluene was investigated to 473 K and 3000 bar. For these liquid hydrocarbons, the interfacial tension γ always increases with pressure. At 373 K for water‐n‐hexane γ is 41.8 mN/m at 100 bar and 47.3 mN/m at 2600 bar, respectively. In the water‐gas systems γ decreases with pressure and passes through a flat minimum around 1000 bar. For water‐nitrogen at 373 K γ = 52.5, 46.5 and 48.3 mN/m at 200, 1400 and 2800 bar. Only with water‐helium γ increases continuously with pressure.
Solvation and association of urea in aqueous solutions and mixtures of water with 1‐propanol
Authors: Hawlicka Ewa , Grabowski Roman 
Published: July 2012

AbstractSelf‐diffusion coefficients of urea have been measured at 25.0 °C in aqueous solutions and in mixtures of water with 1‐propanol, as a function of the urea concentration and of the mixed solvent composition. The hydrodynamic radius of urea has been calculated. It has been found that both in aqueous solutions as well as in 1‐propanol‐water mixtures dimers of urea, if they exist, do not play any role in the diffusion processes. Diffusion is, however, a collective process and motions of urea depend on the numbers of neighbours, therefore they are very sensitive on the structure of the solvent. The results have also confirmed the previous supposition that urea does not affect the water structure, but it does fit the water structure quite well. It has been also found that the solvation of urea is determined by the structure of the mixed solvent.
Li insertion into 2H—WS2: Electronic structure and reactivity of the UHV In‐situ prepared interface
Authors: Schellenberger A. , Jaegermann W. , Pettenkofer C. , Kamaratos M. , Papageorgopoulos C. A. 
Published: July 2012

AbstractThe interaction of UHV cleaved 2H‐WS2 crystals with Li deposited at room temperature and at 85 K has been investigated using synchrotron soft x‐ray photoemission. Depending on the Li concentration and the temperature, chemically different interfaces are observed: at 85 K, a small Li concentration x≤0.2 leads to an intercalation phase LixWS2, which can be described in terms of the rigid band model. An intermediate phase occurs for 0.2<x≤1.3. One product of this intermediate phase is assigned to W2S3. With higher Li concentrations, a decomposition reaction sets in producing Li2S and metallic W. This decomposition reaction is favoured by heating the system to 300 K. No intermediate phase is observed in the room temperature experiment. The crystal is directly decomposed producing Li2S and metallic W. The experimental results are discussed in relation to thermodynamic, electronic and kinetic effects.
Photoconductivity in poly(biphenylmethyl silylene)
Authors: Eckhardt A. , Yars N. , Wollny T. , Schnabel W. , Nešpůrek S. 
Published: July 2012

AbstractQuantum yields of charge carrier formation, ϕ; (cc), in poly(biphenylmethyl silylene), PBMSi, and poly(methylphenyl silylene), PMPSi, have been determined at 23 °C with the aid of the xerographic discharge method. At F = 1 × 108 V/m and λinc = 330–360 nm: ϕ (cc) = 0.10 (PBMSi) and ϕ (cc) = 0.03 (PMPSi). Upon the addition of 2,3,5,6‐tetrachlorobenzoquinone (chloranil) at c = 3 mol%, to the polysilylene films, the quantum yields were increased: ϕ (cc) = 0.21 (PBMSi) and ϕ (cc) = 0.13 (PMPSi). The mobility of charge carriers μ in PBMSi is about one order of magnitude lower than in PMPSi. Upon addition of 3 mol% chloranil to PBMSi μ increased slightly.
Comment on “relaxation spectroscopy of electrolyte solutions: LiClO4 in tetraethyleneglycol dimethylether”
Authors: Schütz G. , Stockhausen M. , Firman Paul , Xu Meizhen , Eyring Edward M. , Petrucci Sergio 
Published: July 2012

AbstractRadio frequency and microwave frequency complex dielectric permittivity ϵ* = ϵ′ ‐ iϵ″ data for LiClO4 in tetraglyme as well as similar previously published data for LiNO3 in liquid polyethylene oxides are reviewed. The reliability of the dielectric ion coefficient ϵ″d at concentrations C ≫ 0.1 M (obtained as the difference between the total loss ϵ″ and the conductance loss ϵ″x = 1.8×1012χ/f) is questioned for frequencies f ≤ 0.1 GHz. The interpretation of the dielectric spectra of LiClO4 (and of LiNO3) in polyethers is critically analyzed.