bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poster Contributions. Double Pulse 2D LIF as a Means for Following Flow and Chemistry Development in Turbulent Combustion
Authors: Atakan B. , Jörres V. , Kohse‐Höinghaus K. 
Published: July 2012

AbstractA new approach for the measurement of turbulence time scales was developed based on double‐pulse two‐dimensional laser‐induced fluorescence in combination with a correlation analysis. In a first application, the reaction zone of a turbulent H2/air diffusion flame was studied with this method. For this, OH molecules were excited using two laser pulses which were delayed with respect to each other, but which pumped the same transition in the OH A‐X (1,0) band. The laser‐induced fluorescence of the same spatial region was detected using two gated CCD cameras. By varying the time delay between the laser pulses from 5 μs to 1 ms, the temporal changes of the OH‐ containing structures were determined. Spatial structures were also examined. Correlation analysis was used for a quantitative evaluation of the experimentally observed time and length scales for the regions where OH was present. The double‐pulse 2D LIF method appears to be a promising tool for the investigation of turbulent flows. Its applicability is not limited to the example presented here. With the possibility to detect stable as well as radical species, it may provide a wealth of data on the temporal and spatial changes of a variety of scalars in both non‐reacting and reacting turbulent flows which can be compared to mathematical turbulence models.
Monte Carlo simulation studies of binary mixtures: A measure of the mixing
Authors: Karaaslan Hasan , Yurtsever Ersin 
Published: July 2012

AbstractA Monte Carlo algorithm tailored to fast equilibration of binary mixtures is applied to Lennard‐Jones fluids and solids. In order to study phase transitions as functions of interaction parameters as well as of the temperature, a measure of the mixing is defined which is based on the normalized differences of radial distribution functions. At all temperatures sharp transitions are observed when the ratio of the interaction strengths of like and unlike particles reaches a threshold value.
Kinetics and mechanisms of the formation of iron(III) complexes with Nα‐pyridoxyl‐L‐phenylalanine, Nα‐pyridoxyl‐L‐alanine, and Nα‐pyridoxyl‐L‐aspartic acid
Authors: Ozawa Tomohiro , Jitsukawa Koichiro , Masuda Hideki , Einaga Hisahiko 
Published: July 2012

AbstractThe coordination reaction characteristics and mechanisms of the title new ligands (1(H2plpa), 2(H2plal), and 3(H3plas) stated in the order) to iron(III) have been investigated in an aqueous 0.10mol dm−3 sodium perchlorate solution at 25°C by means of electronic absorption spectral and stopped‐flow spectrophotometric methods. They equally form the corresponding bis(ligand)iron(III) complexes with slower coordination of the first one through the same two parallel pathways of Fe3+ +H3+L + (or 0) and FeOH2+ +H4L2+(or +) and also another pathway of FeOH2+ +H3L+(or0) (L is fully deprotonated species of 1, 2, and 3); the mechanistic rate‐determining step is the coordination of phenolato oxygen of the first ligand. The thermodynamic stability constant (log β12/mol−2dm6. 0.10mol dm−3 (NaClO4), 25°C) of iron(III)‐3 complex (48.33±0.21) is very large in comparison with the constants of the iron(III) complexes of 1(39.06 ±0.26) and 2(39.81 ± 0.20). A possibility is concluded for the formation of more stable iron(III) complexes without changing the complex formation reaction mechanism by designing the ligand structure of the amino acid moiety of pyridoxal‐L‐amino acid derivatives as a siderophore.
On further treatment of oxidic‐hydroxidic compounds in partly discharged electrodes on the basis of structural investigations of manganese dioxide
Authors: Axmann P. , Glemser O. 
Published: July 2012

AbstractThe effects of further treatment of aquoxide electrodes, e.g. storage in the electrolyte, washing and drying are studied by means of X‐ray investigations. These methods of treatment lead to the disappearance of the reflections of β‐Mn(OH)2 which is formed initially in a partly discharged electrode. Simultaneously new reflections arise, showing the formation of β‐MnOOH.
Surface chemistry of colloidal gold: Deposition and reoxidation of Pb, Cd, and Tl
Authors: Henglein Frank , Henglein Arnim , Mulvaney Paul 
Published: July 2012

AbstractLead, cadmium and thallium are deposited on colloidal gold particles in aqueous solution. The deposition occurs through the reduction of the metal ions by excess electrons which are donated to the gold particles by free organic radicals generated radiolytically. The absorption spectra of the composite particles are measured and compared to calculated ones (using Mie theory and the optical constants of the pure metals). — Au‐Pb particles are stable and well separated, and there is reasonable agreement between experimental and calculated spectra. Reoxidation of the lead mantle by Ag+ ions leads to a silver mantle, although about 5% of the deposited lead is not oxidized; this is attributed to the strong binding of Pb adatoms to the gold surface. The reoxidation of Pb adatoms by Ag+ occurs much more slowly than the oxidation of individual Pbn particles, which is attributed to the more electropositive nature of the deposited metal. — Au‐Cd particles tend to agglomerate, especially when the Cd mantle is reoxidized by Ag+ ions. The resulting Au‐Ag particles contain a large percentage of non‐oxidized cadmium; alloy formation seems to be a possible explanation. — The spectra of Au‐Tl particles are not in good agreement with the calculated ones; it seems that the reduced Tl does not form an even mantle around the Aun particles.
Ultrasonic absorption of aniline/cyclohexane mixtures of critical and non‐critical composition
Authors: Bittmann E. , Alig I. , Woermann D. 
Published: July 2012

AbstractResults of measurements of the temperature and frequency dependence of ultrasonic absorption (a/f2) of aniline/cyclohexane mixtures of critical and non‐critical composition are reported. The data obtained with the mixture of critical composition are analysed in terms of the Ferrell‐Bhattacharjee theory (Phys. Rev. A31, 1788 (1985)). The value of the critical amplitude ω0 of the relaxation rate used for calculation of the scaling variable Ω is obtained from static and dynamic light scattering data taken from the literature (ω0 = (42±3)GHz). This value of ω0 agrees with that obtained from a fit of the dynamic scaling function F(Ω) to the experimental ultrasonic absorption data (ω0 = (42±5) GHz).
On‐line multi‐photon ionization mass spectrometry applied to PAH and fullerenes in flames
Authors: Ahrens J. , Kovacs R. , Shafranovskii E. A. , Homann K. H. 
Published: July 2012

AbstractA new approach is presented, that enables on‐line detection of large polycyclic aromatic hydrocarbons (PAH) and fullerenes in premixed flat low‐pressure flames by molecular beam resonance‐enhanced multiphoton ionization mass spectrometry (REMPI‐MS). A multi‐pass mirror system for the laser beam was developed to increase the amount of ions formed. In benzene/oxygen flames, PAH with molecular masses up to more than 103 u were observed. For the first time, this method has also provided on‐line mass spectra of electrically neutral flame‐generated fullerenes (C32 to about C300) after the investigation of fullerene flame ions. The fragmentation induced by laser irradiation is discussed.
Fiber‐optic diffusing‐wave spectroscopy on concentrated dispersions of large polymer latex spheres
Authors: van Keuren E. R. , Wiese H. , Horn D. 
Published: July 2012

AbstractFiber‐optic diffusing‐wave spectroscopy (FODWS) measurements were carried out on polymer latex dispersions (10 wt%) with large particle diameters (1.07, 3.2 and 5.6 μm). Autocorrelation functions (ACFs) were measured from light multiply scattered between two single‐mode optical fibers immersed in the dispersion. As expected from a photon diffusion approximation the logarithms of the ACFs were linear functions of the fiber separation and the square root of the correlation delay time. A small downward curvature of the curves at short delay times could be attributed to a slight absorption by the samples. From the ACFs a parameter κ was derived which strongly depended on particle size. Reasonable agreement was found between the experimental κ‐values and predictions by a hard‐sphere model. Potential applications of FODWS are the on‐line process control of emulsions, viscous pigment or ceramic dispersions.
Oscillatory behaviour of density profiles: Relevance for fluid interfacial phenomena
Authors: Evans R. 
Published: July 2012

AbstractFor a given short‐ranged interatomic potential the density profile of an inhomogeneous fluid decays into bulk in the same fashion as the bulk radial distribution function g(r). General statistical mechanical arguments predict damped oscillatory decay of the liquid‐vapour density profile into the saturated liquid for temperatures T removed from the critical value Tc. Explicit density functional calculations for a square‐well model fluid near its triple point yield an oscillatory profile whose amplitude is about 2% of the bulk liquid density. The amplitude decreases for higher T and for T≥0.9 Tc only pure exponential decay is found. Capillary‐wave fluctuations reduce the amplitude of the oscillations but do not change their period and decay length. The existence of density oscillations gives rise to an oscillatory binding potential for an adsorbed liquid film. This has significant repercussions for wetting transitions and allows the possibility of a sequence of layering transitions between adsorbed liquid layers. The same length scales which determine the decay of g(r) determine the asymptotic decay of the solvation force for a fluid confined between two planar walls. In the case of long‐ranged interatomic potentials, density profiles exhibit power‐law decay at longest range but, for liquid densities, their intermediate range damped oscillatory decay is governed by the same leading‐order pole structure that describes short‐ranged forces. Recent work on the decay of correlations in liquid mixtures is also described.
Nematic and smectic surface order in the isotropic phase of low molar mass and polymeric liquid crystals
Authors: Immerschitt S. , Elben H. , Holthoff H. , Strobl G. 
Published: July 2012

AbstractPretransitional surface ordering phenomena, as they occur in the isotropic phase of liquid crystals upon approaching the clearing point, were studied by variable angle ellipsometry and X‐ray reflectivity measurements. Ellipsometric data obtained for two phenylcyclohexanes indicate a logarithmic divergence of the thickness of a nematic boundary layer with homeotropic orientation, which corresponds to a complete wetting behaviour. Data can be represented by a model based on a Landau‐de Gennes approach. An investigation of a LC‐side group polyacrylate showed a boundary layer with planar orientation. The thickness, which increases on approaching the clearing point, is clearly larger than in the case of the low molar mass samples. In X‐ray reflectivity studies on a film of a LC‐side group polymer boundary layers with smectic order were detected. They possess a remarkable stability and exist also at larger distances from the clearing point. A stepwise procedure in the data analysis enables a detailed, complete characterization.
Continuous Wetting Transitions in Systems with Van der Waals Interaction
Authors: Fenzl Willi 
Published: July 2012

AbstractWetting transitions in systems with long‐ranged interactions are now well understood theoretically. Although the existence of continuous transitions is predicted, an experimental example has not been found to date. The search for an appropriate system is supported by a calculation of the free energy of interfacial interaction for liquid films on solid substrates within the framework of the Dzyaloshinskii, Lifshitz and Pitaevskii theory of Van der Waals interaction. It is shown that a minimum in the interfacial interaction energy can be obtained by the competition of the nonretarded zero‐frequency and the retarded dispersion term, if they have comparable magnitude and different sign. In certain systems the zero frequency term changes its sign on varying the static dielectric constant of the substrate or the liquid. Then, in combination with a repulsive dispersion interaction, the necessary conditions for a continuous wetting transition are fulfilled. The possibility of realizing this transition experimentally is discussed.
Line tension at continuous wetting
Authors: Backx G. , Indekeu J. O. 
Published: July 2012

AbstractThe interface displacement model has proven very useful for calculating the line tension τ near first‐order and continuous (critical or multicritical) wetting transitions. Since the upper critical dimension, du, for contact line phenomena has been argued to be the same as for surface phenomena at wetting, it follows that du < 3 for intermolecular forces with algebraic decay. Consequently, the mean‐field exponents for τ should be exact in d = 3, for most experimentally relevant systems. Here we review the mean‐field results for continuous wetting.
Transport phenomena in physisorbed films: Investigations with optically excited surface plasmons
Authors: Herminghaus S. , Sigel U. , Paatzsch T. , Musil H. , Leiderer P. 
Published: July 2012

AbstractExperiments were performed on the lateral transport kinetics of wetting layers. Optically excited surface plasmons were used to study both the spreading behaviour of silicon oil and the equilibration dynamics of ethanol. The precursor film profiles of silicon oil were found to agree well with the theory of viscous flow of nonvolatile liquids. For ethanol, evaporation effects and viscous transport could be observed separately. Apparently, the viscous transport is suppressed by almost two orders of magnitude. Possible explanations are discussed.
Dynamical formation of metastable phases at interfaces
Authors: Löwen Hartmut 
Published: July 2012

AbstractA Ginzburg‐Landau model of non‐conserved order parameter dynamics is analyzed. The model involves three different phases: a stable high‐temperature phase, a stable low‐temperature phase and a metastable phase. It is shown that a macroscopic portion of metastable phase can be formed by a dynamic instability which splits the front separating the stable high‐ and low‐temperature phases. The presence of an external field blocks this metastable phase formation and leads to a non‐monotonic behaviour of the metastable phase portion as a function of time.
Critical adsorption of SF6 on a finely divided graphite substrate
Authors: Thommes M. , Findenegg G. H. , Lewandowski H. 
Published: July 2012

AbstractThe adsorption behavior of a near‐critical fluid (SF6) on a finely dispersed graphitic adsorbent (graphitized carbon black; Vulcan 3‐G) has been studied. The surface excess concentration γ was measured by approaching the critical point along near‐critical isochores using a volumetric technique. From the scaling theory of critical adsorption by Fisher and de Gennes it is expected that γ diverges at the critical point. At temperatures well above criticality of the fluid (T–Tc≥ 3 K) we find the expected increase of Γ with decreasing T; however, closer to Tc the adsorption does not increase further but decreases sharply for T → Tc. This unexpected behavior was also found when the experiment was repeated under microgravity conditions on the space platform EURECA I. A similar maximum in Γ(T) was also observed for SF6 adsorbed in a mesoporous controlled‐pore glass (CPG‐10) with 31 nm mean pore diameter.
Cross over towards the reflectivity discontinuity at total reflection edge. A test for the observation of critical adsorption profiles
Authors: Sans A. , Jannink G. 
Published: July 2012

AbstractWe propose to use the discontinuity at total reflection as an experimental test of the universal critical adsorption profile. Neutron optical properties corresponding to the cross over state are derived from the wave equation, and exact results are displayed. They indicate that the critical index can be derived from experimental data, at a reasonable vicinity of the critical temperature.
Liquid monolayers. Dynamical lateral order in binary lipid alloys and its coupling to membrane functions
Authors: Knoll Wolfgang 
Published: July 2012

AbstractThis contribution deals with the relation between the dynamical lateral order in model membranes composed of lipid mixtures, and its influence on the function of an integral model protein, the ion‐channel gramicidin. Firstly, densitometric and small angle neutron scattering experiments are described for binary alloys organized as liposomal dispersions. These results establish some basic concepts for the understanding of the phase behavior, mixing properties and critical lateral compositional fluctuations in these quasi two‐dimensional fluid systems. Next it is shown how the current fluctuations across a bimolecular lipid layer observed when two monomeric gramicidin molecules dimerize within the membrane thus forming an ion‐conducting channel can be analyzed to give information about the lateral organization of the lipid matrix. It is shown that phase separation and critical fluctuation, indeed, control the performance parameters of a membrane‐integral functional unit.
Mixed polymer‐surfactant layers at the air‐water interface
Authors: Mann E. K. , Langevin D. , Hénon S. , Meunier J. , Lee L. T. 
Published: July 2012

AbstractWe have studied mixed molecular layers of polydimethylsiloxane (PDMS) and surfactants, using different techniques: surface tension, ellipsometry, neutron reflectivity and Brewster angle microscopy. On pure water, the polymer layer is generally inhomogeneous, showing surface domains of different discrete thicknesses. The penetration of the polymer into the surfactant monolayer found on the surface of aqueous surfactant solutions depends on the surfactant. On a surfactant layer with little penetration by the polymer, the polymer layer remained inhomogeneous. With other surfactants, the polymer penetrated appreciably into the surfactant layer, and the polymer layer was homogeneous. These differences between surfactants correlate with the wetting behavior of PDMS on the aqueous surfactant solutions.
High pressure heat capacity of benzene derivatives from pVT measurements
Authors: Cáceres Mercedes , Baonza Valentín G. , Rubio José E. F. , Arsuaga Jesús M. , Núñez Javier 
Published: July 2012

AbstractAccurate thermal expansion coefficient αp, speed‐of‐sound and density measurements found in the literature have been used to characterize the general behavior with pressure of the constant pressure heat capacity Cp of benzene and toluene. The results agree well with direct measurements of Cp found in the literature. Indirect methods for estimating Cp at high pressures are discussed. αp results obtained with an expansion technique using a differential method have been used to characterize the high‐pressure behavior of Cp for mesitylene.
Polymerization‐pressure dependencies of properties of perfluorosulfonate cation‐exchanger thin films by plasma polymerization
Authors: Yasuda Kazuaki , Uchimoto Yoshiharu , Ogumi Zempachi , Takehara Zen‐Ichiro 
Published: July 2012

AbstractPerfluorinated thin cation‐exchanger films fixed with sulfonic acid group were prepared by plasma polymerization of trifluoromethanesulfonic acid and hexafluoropropylene. The influence of polymerization pressure on their structural changes was focused. FT‐IR and ESCA measurements indicated that the decomposition of sulfonic acid group was remarkable under low polymerization pressure conditions. The higher the pressure, the more the decomposition was suppressed and the more the sulfonic acid group was introduced. The plasma polymer formed at polymerization pressure as high as 0.5 Torr was about 1 μm thick and free from pinhole, and gave an ionic conductivity of 1.8×10−4 S cm−1 and a K+ transference number was as big as 0.99 in an aqueous KCl solution showing a high cation perm‐selectivity.
Description of alkali‐arsenic (antimony) clusters using one‐electron extended Hückel energies with two‐body repulsions and geometry optimization
Authors: Lies Hartmut , Böhm Michael C. , Weil Konrad G. 
Published: July 2012

AbstractGeometries of clusters formed by the group‐V‐atoms As, Sb and alkali metals M = Na, K, Cs are studied by extended Hückel (EH) calculations supplemented by a repulsive two‐body interaction and a geometry optimization of the Fletcher‐Powell‐type. The computational results are compared with available ab initio and pseudopotential data as well as experimental findings. The improved EH formalism allows a straightforward analysis of geometric preferences of clusters as a function of the alkali coordination. These findings are then interpreted in terms of qualitative orbital pictures. For clusters containing four group‐V‐atoms, e.g. As4, Sb4, M2As4, M2Sb4, M4As4, M4Sb4, M6As4, M6Sb4, it is shown that the geometry of the central As4 (Sb4) unit depends on the number of valence electrons. The bare As4 and Sb4 clusters have a tetrahedral Td minimum, while the metal‐to‐group‐V‐atom electron transfer in the alkali coordinated systems stabilizes a square‐planar As4 (Sb4) arrangement of D4h symmetry.
Pressure induced lattice distortion in some Co(III)‐Ammine complexes, [Co(NH3)5NO2]XY (XY = Cl2, Br2, ClNO3))
Authors: Boldyreva Elena , Ahsbahs Hans , Uchtmann Hermann 
Published: July 2012

AbstractLattice parameters were measured at pressures up to 4GPa (40kbar) for [Co(NH3)5NO2]XY (XY=Cl2, Br2, Cl(NO3)) by X‐ray powder diffraction using a Diamond Anvil Cell (DAC) technique. Continuous anisotropic lattice distortion with increasing pressure was observed. Strain tensors were calculated at different pressures, and the orientation of strain ellipsoids with respect to the crystallographic axes and the directions of various bonds in the structures was considered. Pressure induced lattice distortion was compared with lattice distortion in the course of homogeneous nitro‐nitrito linkage isomerization in the crystals. The data on the orientation of Co‐NO2 bonds with respect to the directions of main compression in the crystals correlate with previously obtained data on pressure induced frequency shifts in the solid state IR‐absorption spectra in the same series.
The structure of cold condensed lead chloride (PbCl2)
Authors: Zuber Ralf , Weil Konrad G. 
Published: July 2012

AbstractWhen lead chloride is deposited onto substrates at temperatures below 150 K, a non‐crystalline film is formed. This material crystallizes at temperatures above 260 K, as could be demonstrated by UV‐VIS‐spectroscopy. In order to determine whether or not the deposited material consists of extremely small crystals with a high degree of disorder or of a genuine amorphous phase, it was investigated by electron diffraction. We describe the procedure which we applied for the determination of the elastically scattered intensity as a function of the scattering vector. From this function, the reduced radial distribution function was determined. The results were compared with those reported about crystalline and molten lead chloride. The short range order in the cold condensed material is different from that in the crystal and that in the melt. Hence, cold condensation of lead chloride leads to the formation of an ionic glass.