bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur physikalisch‐chemischen Wirkungsweise von Waschmittel‐Gerüststoffen
Authors: Große J. , Nielen H.‐D. 
Published: March 2014

AbstractThe physicochemical properties of detergent builders are discussed with special respect to pentasodium triphosphate, Na5P3O10 (NTPP). The builder action can be interpreted in terms of colloidochemical theories. — Laboratory screening tests concerning calcium binding capacity, dispersing action and “threshold” effect of typical builder components are presented. — Detergent builders are also characterized by means of polyelectrolyte titration. Zeta potential data obtained on cotton fabrics are also included. — The results of the various experiments — screening tests as well as electrokinetic measurements — are discussed and verified by means of model washing tests.
Der Einfluß von pH, Elektrolytkonzentration und Mischverfahren auf die Flockung von gefällten und pyrogenen Silikahydrosolen durch Polyethylenglykol
Authors: Killmann E. , Gütling N. , Wild Th. 
Published: March 2014

AbstractWith a laser photosedimentometer one obtaines parameters which enable characterization of the turbidity and of the sedimentation in the Silica suspension flocculated by the adsorption of Polyethyleneglycols. By continuous addition of the polymer solution to the silica suspension the influences of the time of addition, stirring time, stirring intensity, polymer coverage, concentration of silica, pH and ionic strength on the flocculation state can be quantified. In contrast to pyrogenic silica precipitated silica is only flocculable by decreasing the pH below pH 3.5 or by addition of salt above 10−2 mol/l. The flocculation of pyrogenic silica is markedly dependent on the mixing conditions at high pH and without salt. At high salt concentrations and pH <3.5 the flocculation of precipitated and pyrogenic silicas becomes independent of mixing conditions.
Kalorimetrische Untersuchungen zur Adsorption von Tensiden an Mineralen
Authors: von Rybinski W. , Schwuger M. J. 
Published: March 2014

AbstractA process for the separation of finely disseminated ores is the selective agglomerate flotation. In this technique surfactants are adsorbed at the mineral particles making their surface hydrophobic. In a second step the particles are tumbled in an aqueous solution containing an unmiscible bridging liquid which causes their selective agglomeration. The interaction between the adsorbed surfactant molecules and the mineral surface is decisive for high selectivity and recovery of the agglomeration process. This could be shown by calorimetric measurements of the heat of adsorption of sodiumoleate and sodiumhexadecylsulfate at scheelite and calcite. In adsorption of surfactants from aqueous solution at mineral surfaces effects as solubility of the minerals and the precipitate formation of surfactants with polyvalent ions have to be taken into account. By means of calorimetric measurements it could be distinguished, whether there is interaction between the mineral surface and adsorbed surfactant molecules, double layer adsorption or precipitate formation.
Direct Investigation of the Reaction CH2(X̃3B1) + O(3P) with the LMR
Authors: Böhland T. , Temps F. , Wagner H. Gg. 
Published: March 2014

AbstractThe reactionhas been studied at room temperature in an isothermal discharge flow reactor. Methylene‐radicals and oxygen‐atoms have been monitored with a Far‐Infrared Laser Magnetic Resonance spectrometer. The rate constant of reaction (1) was evaluated from the pseudo first order decay of CH2in the presence of a large excess of O‐atoms. The influence of side and consecutive reactions has been investigated in a computer simulation of the reaction system. — The final result for the rate constant of reaction (1) isThe experimental value is compared to theoretical predictions for the high pressure recombination rate constant of CH2and O.
Calculation of Isothermal Compressibilities of Mixtures. The Example Acetone + Chloroform
Authors: van Nhu Nguyen , Bhat Subray N. , Kohler Friedrich 
Published: March 2014

AbstractFrom measured values of excess volumes vE at normal pressures, and from molar volumes and isothermal compressibilities of the pure components, compressibilities of the mixtures can be calculated by means of a generalized van der Waals equation of state. Similarly, excess volumes at elevated pressures can be calculated. This is shown for the example of the mixture acetone + chloroform, where newly measured values of vE and of isothermal compressibilities are presented. The agreement between calculation and experiment is within the experimental accuracy. The equation of state calculations give even reasonable agreement to vE‐measurements by Kulka and Schneider at 150 MPa.
Chemical Potential Measurements on Nonhydrostatically Stressed Solids
Authors: Durham W. B. , Schmalzried H. 
Published: March 2014

AbstractGibb's hypothesized dependence of chemical potential upon state of stress has been qualitatively confirmed by direct measurement, using solid‐state electrolytes both to transmit nonhydrostatic load and to measure (through a change in electrical potential) a corresponding change in chemical potential. Quantitative agreement with Gibbs predictions may not be possible because of the inevitable presence of nonideal chemical heterogeneities near the surfaces of solids.
Vapour Pressure of the AlCl3‐POCl3 System
Authors: Brockner Wolfgang , Grande Knut , Øye Harald A. 
Published: March 2014

AbstractThe vapour pressure and vapour compositions have been determined for the molten AlCl3‐POCl3 system in the composition range 50–64 mol% AlCl3 and for temperatures in the range 170–270°C using a boiling point method and analyzing the boiled‐off vapour after direct condensation. Knudsen effusion cell measurements of the solid AlCl3 · POCl3 compound have also been carried out. The melts are considered as molecular liquids consisting of Al2Cl6, Al2Cl6 · POCl3, AlCl3 · POCl3 and POCl3 molecules, respectively. The vapour species are Al2Cl6, AlCl3 · POCl3 and POCl3, A semiempirical thermodynamically based melt model has been developed explaining the vapour pressure minimum of acidic AlCl3‐POCl3 melts and the published azeotrope at 51.5 mol% AlCl3. Thermodynamic data have been calculated.
An infrared‐spectroscopic study on the state of water in alcohols and in inverted micelles
Authors: Rosenholm Jarl B. 
Published: March 2014

AbstractThe shifts of the antisymmetric stretching vibration bands of water (σ3) and of the ionized carboxylate group (σcoo) in the fundamental infrared region has been used to investigate the properties of water when mixed with pentanol or decanol and when engaged in the association to inverted micelles in the same solvents at 298 K. The systems studied were water + sodium n‐octanoate in pentanol and decanol, respectively. In order to identify the states occupied by water a method was developed to resolve the observed average wave number into the contribution of the different states. The Boltzmann‐distribution is utilized to give a rough estimate of the amount of water present in each state. When water is dissolved in pentanol it is initially bound to strong complexes with the alcohol molecules. In the high concentration range a part of the water seems to be dispersed free in the solvent. Diluted in decanol all the water seems to be engaged in intermolecular complexes characterized by strong hydrogen bonds. Present as hydration water of the ionic groups of the surfactant monomers the water is bound with an average strength resembling that of liquid water. The micellization seems to be initiated in all solutions investigated when the amount of hydrated surfactant is sufficiently high. Independent of the relative amount of water present the sodium ions seem then to be partly released from the strong ionic interaction found in the premicellar solutions. On the other hand, the fraction of water available is of prime importance for the state of the carboxylate group.
Fluorescence excitation spectra of hydrogen‐bonded cresol‐isomers in supersonic free jets
Authors: Appel I. , Kleinermanns K. 
Published: March 2014

AbstractFree o‐, m‐ and p‐cresol and their complexes with H2O, CH3OH and cresol were cooled in pulsed supersonic nozzle beams and analyzed by fluorescence excitation spectroscopy. Results on the cis‐/trans isomerism of the OH group with respect to the CH3substituent and on the hindered internal rotation of the CH3 group were obtained. All the solvents studied induce red shifts of the cresol absorption between 230 and 420 cm−1, reflecting a strong increase in the hydrogen bond dissociation energy upon electronic excitation. Progressions of intermolecular cluster stretching and bending frequencies and their combination bands with intramolecular cluster vibrations were observed. From the red shifts and the break‐off points of the fluorescence signals in the high energy region of the cluster spectra, lower limits of the hydrogen bond energies in the electronic ground (S0) state were obtained. — The experimental results are compared with semiempirical quantum chemical calculations at the Hartree‐Fock level. Monomer and cluster structures and intermolecular stretching and bending frequencies were calculated. The comparison points to several stable conformations of the 1:1 complexes.
Hydrogen equilibrium separation factors in metal/hydrogen systems, a synopsis on the basis of the localized harmonic oscillator model
Authors: Andreev B. M. , Sicking G. H. 
Published: March 2014

AbstractThe isotopic equilibrium separation factor between gas phase hydrogen and hydrogen in metals is calculated for H‐D mixtures and H‐T mixtures between 150 K and 1000 K. Parameter for the calculations is the vibrational energy of hydrogen in interstitial lattice positions. The interstitial hydrogen isotopes are treated as localized Einstein‐oscillators of three‐fold degeneracy. The influence of lower point‐symmetries of interstitial positions is discussed by way of the Ta/hydrogen system as an example. The separation factors evaluated relate to tracer conditions as established with vanishing concentrations of deuterium (tritium). It is shown, how the separation factor for optional deuterium (tritium)‐concentrations in the gas phase is obtained from the tracer separation factor in question. — Special attention is drawn to the fact that metal/hydrogen systems, which dissolve hydrogen in tetrahedral interstitial positions, invert the direction of the isotope effect at a certain temperature. Inversion temperatures are given as a function of the local mode energy. Systems with H in octahedral (tetrahedral) positions are discussed with respect to technical utility. — The calculations are examined by means of experimentally determined separation factors and in the light of recent neutron vibrational spectroscopy work on metal/hydrogen systems.
Characterization of highly repeated sequences in eukaryotic DNAs by scanning microcalorimetry
Authors: Klump Horst H. 
Published: March 2014

AbstractOur observation indicates at least four satellite DNAs in the calf, three in the human placenta, and none in chicken erythrocytes. We estimate that these satellites DNAs comprise up to 25% of the total calf genome and 12. 6% of the bulk human DNA. The individual repeated sequences show up in the experimental thermal transition curve from the scanning microcalorimeter as sharp peaks on top of a rather broad denaturation of common gene pool sequences of eukaryots. The individual satellite DNAs can be characterized by the position of the peak maximum on the temperature axis. The transition temperature Tm can be correlated to the base composition of each repeated sequence (40% GC for bulk calf DNA, 40%, 44%, 48%, 55%, and 62% for the satellites). The comparison with the transition curve of DNA that lacks satellites such as from chicken erythrocytes allows to determine the fraction of the individual satellites in the gene pool of the species.
Modelization of the electrical double layer: Structure of an lon‐dipole mixture near a wall
Authors: Rosinberg M. L. , Russier V. , Badiali J. P. , Boudh'hir M. E. 
Published: March 2014

AbstractWe present a statistical mechanical study of the structure of a hard sphere ion‐dipole mixture in the vicinity of a hard plane wall. We investigate the orientation ordering of the dipoles, the influence of an adsorption potential on the potential drop and the modifications of the ionic solvation.
The jellium/hard sphere electrolyte interface
Authors: Henderson Douglas , Leiva Ezequiel , Schmickler Wolfgang 
Published: March 2014

AbstractA model of the metal/electrolyte interface in which the ions and solvent molecules are represented as charged hard spheres and hard spheres with imbedded point dipoles, respectively, and the metal is represented as a “jellium” is formulated and applied. In some of the calculations a pseudopotential is used to represent the metal ions. Two families of trial functions are used to obtain the electronic profile. Near the point of zero charge (PZC) the mean spherical approximation is used to obtain electrolyte properties. Away from the PZC a phenomenological extension of the mean spherical approximation is used. The results are in good agreement with experiment. The electronic density is found to be the key metallic parameter. The pseudopotential seems to be particularly important for fourth and fifth column sp metals.
Interfacial electrodynamics of interacting colloidal particles. Geometrical aspects
Authors: van Leeuwen H. P. , Lyklema J. 
Published: March 2014

AbstractThe paper treats the effects of geometrical factors on the various double layer relaxation processes which may occur during interaction between colloidal particles. It is explained how the existing theory for interaction between flat plates can be extended to more involved geometries by taking into account the effective region of double layer overlap. Furthermore, the relation between particle interaction dynamics and the kinetics of electrodes of the same material is discussed in terms of the difference in geometry. Finally it is examined how the dielectric relaxation of a colloidal dispersion can be related to the electrodynamics of interaction between individual particles. Some conclusions are drawn on the occurrence of diffuse layer relaxation and interfacial transfer of exchangeable ions in the colloidal system.
Quantum‐mechanical model for surface (Un‐)enhanced resonance raman scattering of adsorbates at metals. Common effects in SERRS and SUERS
Authors: Pettinger B. 
Published: March 2014

AbstractA recently developed quantum‐mechanical model for surface enhanced (resonance) Raman scattering (SERRS) has some implications for surface resonance Raman scattering (SURRS) in general: The molecule‐metal interaction for SURRS at any smooth metal surface is similar to that of SERRS except for the electromagnetic surface enhancement Hence, the total SURRS process consists of (i) a lossy coupling of an induced dipole to electron hole pairs, (ii) an increase of the resonance Raman contribution over the RRS gain of the unbonded species due to a suppression of molecular dephasing and relaxation caused by energy transfer molecule → metal and (iii) the usual resonance Raman contribution; the latter two mechanisms require some molecular resonance with the exciting photon energy (or CT resonance between adatom and adsorbate). In the case of molecular (pre‐) resonance, the loss (i) and the gain (ii) cancel each other. Thus, the overall photon scattering shows either a loss (process i) or an apparently unperturbed, (pre)‐resonance Raman enhancement (e.g. process iii).
The influence of the double layer field on the protonation equilibrium of adsorbed methyl orange
Authors: Schmidt P. H. , Plieth W. J. 
Published: March 2014

AbstractThe protonation/deprotonation of methyl orange adsorbed on a smooth platinum electrode has been investigated by modulated reflectance spectroscopy in the visible spectral region. The modulated reflectance spectra are mainly governed by the potential modulation of the protonation equilibria of methyl orange and the buffer (acetate/acetic acid), respectively. The pK values of the protonation equilibria within the adsorption layer change with the electrode potential E in the following way: dpK/dE = 0.8 V−1 and —1.0 V−1 for methyl orange and acetic acid, respectively.
The adsorption of carbon monoxide on platinum single crystals in alkaline medium
Authors: Leger J.‐M. , Beden B. , Lamy C. 
Published: March 2014

AbstractThe adsorption of carbon monoxide on low‐index platinum single crystals is studied in alkaline medium with a special computer potential‐time programme, which allows to control short adsorption times. — Two or three different adsorbed CO species are involved depending on the crystal planes, and on the adsorption time. At long adsorption times, apart linearly bonded species, bridge‐ or multi‐bonded CO species are still present on each surface, in contrast to the observation in acid medium. — On the other hand the behaviour of a polycrystalline Pt electrode is similar to that of Pt(100) at short adsorption times, and of Pt(110) at long adsorption times.
The electrochemical behaviour of n‐type silicon (111)‐surfaces in fluoride containing aqueous electrolytes
Authors: Gerischer Heinz , Lübke Margot 
Published: March 2014

AbstractN‐type Si(111)‐electrodes have been studied in the dark and under illumination. A limiting current is found at modest anodic bias which increases with the fluoride concentration and is controlled by a chemical reaction. Near the open circuit potential where anodic oxidation and cathodic hydrogen evolution occur simultaneously a chemical reaction of surface atoms with water is involved. All processes in the dark seem to occur only at structural defects of the surface. — Reactions with holes control the current at anodic bias under illumination. The photocurrent doubling in fluoride solution could be confirmed. This effect disappears however with increasing pH if the photocurrent exceeds the rate of conversion of primary oxidic products into soluble silicon fluorides. A structural and energy model is presented in order to explain the results.
Reactions on colloidal semiconductor particles
Authors: Henglein Arnim , Fojtik Anton , Welter Horst 
Published: March 2014

AbstractInorganic colloids such as cadmium sulfide are often used as sensitizers and catalysts for photochemical reactions. In these reactions, which are described in terms of the concepts developed in electrode kinetics, electrons are transferred between the particles and molecules in the solution. Extremely small particles (Q‐particles) often have optical and catalytic properties different from those of the macrocrystals. These effects are due to the restriction in space of the charge carriers produced by light absorption (size quantization). CdS particles carrying an excess electron strongly change their absorption at wavelengths near the absorption edge. This effect is attributed to the influence of the excess electron on the optical transition leading to the lowest excitonic state in these particles.
Molecular dynamics study of raman scattering and infrared absorption of ferrous and ferric ions in aqueous solution
Authors: Halley J. W. , Hautman J. 
Published: March 2014

AbstractUsing a molecular dynamics computer model of water and ion water potentials we have used earlier to study electrolyte structure, we have calculated the infrared absorption and Raman scattering rates of ferrous and ferric ions in aqueous solution. Results for the Raman scattering from the ferric ion in solution are compared with experiments on molten Fe(NO3)3 · 28 H2O. The comparison suggests some new interpretations of the experiments.
Statistical Weights for Primary Structures of Inhomogeneous Polymer Chains
Authors: Fernández Ariel 
Published: March 2014

AbstractWe analyze the distribution of configurational averages over an ensemble of primary structures. These primary structures are given by base sequences for linear polymers of fixed length N constructed randomly from two different kinds of monomers. The variance V(R2) of the thermally averaged square size of the random coil is calculated by defining a virtual ensemble of homogeneous polymers of length N. This ensemble is determined by effective short range two and three body interactions. We prove that V(R2) increases with the information content given by the length N. Specially, V(R2) ∼ N2.
On the Mechanism of Electroless Copper Deposition
Authors: Wiese Harm , Weil Konrad Georg 
Published: March 2014

AbstractThe mechanism of electroless copper deposition with formaldehyde from alkaline ethylenediamine‐tetraacetate (EDTA)‐containing solutions was studied. Oxidation and reduction could be investigated separately by use of a quartz microbalance in combination with fast solution exchange. It could be confirmed that the reaction is predominantly electrochemical, no indication for a direct electron transfer from a reducing agent to copper ions could be detected. In spite of this the oxidation and the reduction reaction are not independent. Formaldehyde oxidation on copper surfaces is enhanced when simultaneously copper ion reduction takes place. Formaldehyde, on the other hand, does not only act as an electron donor but also generates a catalyst for the copper ion reduction. We suggest that chemisorbed methanediolate anions catalyze the reduction. It can be shown that other substances, which either have a similar structure element as methanediolate or which are known to be specifically adsorbed on copper, also catalyze the copper ion reduction from alkaline, EDTA‐containing solutions.
The Ternary Systems H2O‐CH4‐NaCl and H2O‐CH4‐CaCl2to 800 K and 250 MPa
Authors: Krader T. , Franck E. U. 
Published: March 2014

AbstractExperimental results are reported for the fluid phase equilibria of the ternary system H2O‐CH4‐NaCl and to a lesser degree of H2O‐CH4‐CaCl2. Measurements were extended to 800 K and 250 MPa. A “synthetic” method, described previously, was used, supplemented with an electrolytic indication. The high pressure autoclave with sapphire windows and variable volume together with its auxiliary equipment is described. Pressure‐temperature curves on the three‐dimensionalPTx‐surfaces at constant compositions,x, were obtained (“isopleths”). Data for 21 isopleths with NaCl‐concentrations of 0.6, 1.7 and 8 weight percent relative to water with CH4‐concentrations ranging from 6 to 71 mol percent are presented together with three isopleths for H2O‐CH4‐CaCl2mixtures. Molar volumes at the phase boundary surfaces are given. In comparison with the binary H2O‐CH4system, investigated earlier, the addition of only 0.53 mol% NaCl shifts the range of partial immiscibility to higher temperatures by more than 100 K (for example from 610 to 715 K at 100 MPa for 51 mol% CH4). The shift produced by CaCl2appears to reflect incomplete ionic dissociation at high temperatures. Encouraging results of computations of critical curves using pseudo‐binary approximations and a new equation of state based on defined interaction models are shown.
Cooperative Transfer of Excitation Energy and the Dynamic Structure of Micelles
Authors: Shahinian A. A. , Bagdasarian V. V. 
Published: March 2014

AbstractThe absorption and fluorescence spectra of aqueous solutions of amphiphiles, not containing highly conjugated systems of molecules and dyes, have been investigated in the presence and absence of electrolytes. Splitting of the UV absorption spectra of chromophore groups of amphiphile molecules and fluorescence sensibilization on micelle formation are observed. The presence of fluorescence concentration quench is connected to the quench caused by the decrease of intermolecular distance in the micelle. The fluorescence process is not accompanied by a change in the character of the absorption spectra. A hypothesis is made on the existence of flickering “well ordered” clusters in micelles, having a collective excitation energy (exciton) transfer mechanism. Using the fluorescence quench kinetics method it is shown that the average lifetime of the “well ordered” clusters in the micelle is 5 · 10−8‐10−7 s.