bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electro‐Optical Properties of Rodlike Micelles
Authors: Hoffmann H. , Schorr W. 
Published: July 2012

AbstractIt is shown that the induced electric birefringence in solutions with rodlike micelles is composed of two parts: the intrinsic birefringence and the form birefringence. In many systems both parts are of about the same magnitude but of opposite sign. The form birefringence is always positive while the intrinsic birefringence for hydrocarbon surfactants is negative. The intrinsic birefringence is determined by the optical anisotropy of the alkylchain, the headgroup and the counterion and depends on the configuration of the chains in the micellar assemblies and the orientation of the counterion at the micellar interface. In favorable cases, it is possible to determine the order parameter of the chains inside the micelles. The birefringence can change sign when for the same surfactant ion the counter‐ion is varied. The example of such a system is presented. Solutions of Cetylpyridiniumsalicylate give a negative birefringence while Cetylpyridiniumheptanesulfonate gives a positive one. In mixtures of the two systems the birefringence varies smoothly from negative to positive while the size of the rods is little affected by the change.
The Local Structure in Liquid Mixtures of Acetonitrile with 6 Aromatic Solvents
Authors: Boyadjiev Borislav 
Published: July 2012

AbstractThe chemical shifts of the methyl protons of acetonitrile were measured at 298 K as a function of concentration in 6 aromatic solvents. The local structure of the solutions are interpreted by using the model of hard convex bodies, assuming anisotropic aromatic shielding terms and intermolecular repulsive forces. So the angels α can be determined, which show the intermolecular orientation between the acetonitrile and the aromatic molecules. This way it is possible to calculate the angles β of the orientation between the aromatic molecules. Two different kinds of aromatic solvents could be identified:
benzene, furane, thiophene‐ with intermolecular plane to plane angle β ≈ 60°
pyridazine, pyridine, pyrimidin‐ with intermolecular plane to plane angle β ≈ 30°.
A Lattice Model Approach to Orientational Order in Long Chain n‐Alkanes
Authors: Costas Miguel 
Published: July 2012

AbstractAn equation of state has been obtained for a pure n‐alkane liquid with correlations of molecular orientations (CMO). CMO is simulated by considering small densely packed and loosely packed regions randomly dispersed throughout the liquid. These differ by the presence of holes in the loosely packed regions. The relevant parameter for CMO is the fraction of dense‐packed regions p in the pure n‐alkane. The fraction p decreases rapidly with increase of temperature and increases with pressure. It is found that CMO has a short range segmental rather than molecular character. The model correctly predicts the decrease in energy, entropy and volume brought about by the presence of CMO in the pure liquid. Parameters of the theory are fitted to HE(T) and HE(P) for n‐C12 and the following order contributions to mixing quantities are predicted: dVE/dT, dVE/dP, Δ(γVT), ΔCv and Δ(αγ VT) where α and γ are the thermal expansion and thermal pressure coefficients. Good qualitative and quantitative agreement is found with experiment.
On Complex Formation of BeSO4 in Water ‐ Glycol Mixtures
Authors: Busse G. , Strehlow H. 
Published: July 2012

AbstractUsing the pressure jump technique, four reactions have been observed in the system BeSO4‐water‐glycol, three of which are concerned with the substitution of solvating molecules in the solvation layer of the beryllium ion by the sulfate ion: Of water, of monodentate glycol and of bidentate glycol. The fourth reaction could be attributed to the formation of a bisulfato beryllium complex. Equilibrium and rate constants for the involved reactions have been evaluated from conductivity measurements and from the kinetics. The results are compared with those obtained earlier in other solvent mixtures [1–6]: BeSO4 in water glycol mixtures behaves similar as in other mixtures of hydrogen bond forming solvents (water, formamide, N‐methylformamide, methanol). The substitution rate in different solvatomers Be(H2O)i(glycol)2+4‐i depends only on the kind of solvent being substituted by the sulfate ion, and not on the specific solvatomer. However, the substitution of a bidentate solvating glycol occurs much faster than that of a monodentate one. Furthermore the formation of the bisulfato complex has not been observed in water, in water‐formamide and in water N‐methylformamide solutions, which due to their high dielectric constants form only relatively weak sulfato complexes and undetectable amounts of bisulfato complexes.
Evaporation of Acetonitrile/Water Mixtures Through Ion Exchange Membranes ‐ Influence of Selective Solvation of Counterions on Selectivity
Authors: Hoffmann Edith , Woermann D. 
Published: July 2012

AbstractEvaporation experiments of acetonitrile/water mixtures through ion exchange membranes loaded with potassium and silver ions respectively demonstrate that the extent of enrichment of acetonitrile in the vapor phase is influenced by the selective solvation of the counterions by the components of the mixture.
The Effect of the Interface Velocity on the Plateau Pressure of Intermetallic Compound Hydrides. Theoretical Interpretation
Authors: Park Choong‐Nyeon , Flanagan Ted B. 
Published: July 2012

AbstractIt has been observed that when an intermetallic compound‐H system is in its two‐solid‐phase coexistence region, the addition or removal of small aliquots of hydrogen (small driving forces) leads to larger and smaller values of μH respectively, than do large aliquots (large driving forces). It is proposed that the origin of this phenomenon is due to the effect of the interface velocity on the metal atom pile‐up at the interface between the dilute and hydride phases. Large aliquots of hydrogen lead to rapid initial interface velocities which can result in the destruction of the pile‐up (metal atom equilibrium) at the interface. When the driving pressure during the large aliquot falls below the value needed to maintain v ≥ vc, the pile‐up builds up again but does not reach the composition characteristic of small aliquots. It is shown that the chemical potential of hydrogen will be lower during hydriding for the large aliquot case than for the small aliquot case because the hydrogen chemical potential is a function of the metal atom composition at the interface.
Time Delayed Two Photon Processes: I. One Dimensional Model Approach
Authors: Cribb Peter H. , Brickmann Jürgen 
Published: July 2012

AbstractTime delayed two photon processes via a non stationary intermediate state are studied within a one dimensional model approach involving only harmonic potentials. The transition probabilities are calculated as a function of different potential parameters as well as the second photon arrival time distribution. The special maximum is observed to shift with delay time and to depend on the wavepacket momentum. The influence of the arrival time distribution on the spectrum is washed out by the rapid speading of the intermediate state.
Superstructures on the Polar Faces of Indium Antimonide
Authors: Benz Volker W. , Weil Konrad G. 
Published: July 2012

AbstractA scanning high energy electron diffraction system, working at glancing incidence, was used to investigate the polar (111) In and (&1macr;&1macr;&1macr;)Sb faces of indium antimonide. On the (111) face, argon ion bombardment with subsequent annealing lead to the appearance of a 2×2 superstructure. This superstructure disappears after oxygen admission. The sticking coefficient for oxygen can be estimated to be < 5 · 10−6. The logarithmic intensities of the base lattice reflexes, the superstructure reflexes, and the 1 × 1 reflexes on the oxygen covered surface decrease linearly with temperature leading to the following values for Debye temperatures: θbase latt. = 128 ± 7 K, θsuperstr. = 105 ± 6 K, and θOX = 157 ± 7 K, the latter value being close to that of the bulk lattice (θbulk = 159 K [2]).The (&1macr;&1macr;&1macr;)Sb face shows a more complicated behaviour: removal of approximately 1 monolayer by argon ion bombardment and subsequent annealing below 560 K leads to a 2 × 2 superstructure. Under further annealing above 560 K this transforms into a 3 × 3 superstructure. The 3×3 structure appears immediately, when the argon ion bombardment is more intense and when the annealing temperature is above 630 K. Still stronger ion bombardment leads to the formation of additional reflexes which could be attributed to epitaxially oriented indium precipitates.The base lattice reflexes on the (&1macr;&1macr;&1macr;) surface show normal temperature dependence, resulting in a Debye temperature of 111 ± 5 K. The superstructure reflexes show a linear In I vs T behaviour only below 400 K. In the temperature interval 420 K < T < 520 K. these reflexes completely disappear showing reversible behaviour. This behaviour indicates an order‐disorder‐transition in an adsorbed overlayer.
Pulsed Laser‐Induced Thermal Desorption of Xenon
Authors: Hussla I. , Coufal H. , Trager F. , Chuang T. J. 
Published: July 2012

AbstractA 28 nm thick copper film with a temperature of 20 K, covered with approximately 100 monolayers of xenon is excited with a pulse from a XeCl laser. Time‐of‐flight signals of laser‐induced desorbed xenon are recorded with a quadrupole mass spectrometer. Simultaneously surface temperatures of the.copper film are measured with a pyroelectric calorimeter which serves as substrate for the copper film. The calorimetric temperatures are compared with translational temperatures derived from time‐of‐flight data. In the absence of any rotational or vibrational deexcitation channel, the maximum surface temperatures of the copper film are higher than the translational temperatures of desorbed xenon. In addition, non‐equilibrium desorption is reflected by a non‐Maxwellian line shape of the velocity distribution of desorbing xenon.
Molecular Dynamics of Fluids: The Gaussian Overlap Model II
Authors: Kabadi Vinayak N. 
Published: July 2012

AbstractMolecular dynamics computer simulation results are reported for a model Gaussian overlap potential with the orientation dependence of the well depth adjusted so as to mimic a multiple‐centered 12–6 site‐site potential. At low anisotropy (length to breadth ratios less than 1.55), the thermodynamics of this potential agree well with those for the site‐site diatomic potential when the same length to breadth ratios are used for both. At higher anisotropies, the equivalence is not as good. We have also obtained the parameters for an oblate Gaussian overlap potential (k = 0.50) which yields properties that agree with the thermodynamic data for liquid benzene. In all cases the structure of the Gaussian overlap fluid differs from site‐site and from real fluids, especially with respect to the probabilities of configurations in the T‐shaped orientation. The implications of this finding in relation to the properties of quadrupolar fluids are discussed.
Interactions of Hydrophobic Layer Silicates with Alcohol‐Benzene Mixtures II. Structure and Composition of the Adsorption Layer
Authors: Dékány I. , Szántó F. , Weiss Armin , Lagaly G. 
Published: July 2012

AbstractAdsorption of methanol and benzene on alkylammonium montmorillonite, a hydrophobic layer silicate, changes the orientation of the alkylatnmonium ions at the internal and external surfaces. The hydrophobic chains are pushed off from the surface and assume upright orientations. The methanol molecules are adsorbed preferentially on the silicate surface not covered by alkyl chains, the benzene molecules “solvate” the alkyl chains.—The volume of the adsorbed phase as calculated from the adsorption excess isotherms is smaller than the total interlayer volume occupied by the methanol and benzene molecules. Thus, only a fraction of the liquid between the silicate surfaces is subdued to the adsorption forces. The remaining liquid is considered bulk‐like. The uptake of the bulk‐like liquid in addition to the adsorption phase is apparantly imperative for the process of swelling.
In Situ Photoacoustic Spectroscopy of Electrochemically Grown PbO2 Films. Optical Constants from Photoacoustic Interference Signals
Authors: Dohrmann Jürgen K. , Sander Ulrich 
Published: July 2012

AbstractPhotoacoustic (PA) signals have been measured in situ in the 300–750 nm range during constant‐current growth of β‐PbO2 films on a platinum electrode in aqueous Pb(ClO4)2/HClO4 solution. The structure seen in the PA signals at constant wavelength arises from optical interference. An analysis of the PA signals in terms of reflectivity of the electrode/solution interface is presented, from which the optical constants of the β‐PbO2 film (index of refraction and absorption constant) have been obtained in the 300–750 nm region.
The Effect of Ionic Strength and Pressure on the Complex Formation Kinetics of the Aquated Iron(III)‐Thiocyanate System
Authors: Martinez P. , Mohr R. , Eldik R. Van 
Published: July 2012

AbstractThe kinetics of the complex formation and reverse aquation reactions in the aquated iron(III)‐thiocyanate system were studied as a function of ionic strength (0.1 to 1.5 M) and pressure (up to 120 MPa) using a high‐pressure temperature‐jump technique. Volumes of activation for the various reaction steps were estimated from a combination of the kinetic data with the ionic strength and pressure dependencies of the overall equilibrium and acid dissociation constants determined before. The volume of activation for complexation of Fe(H2O)5OH2+ by SCN− exhibits a significant ionic strength dependence and possible explanations are offered. The results are compared and discussed in reference to earlier reported data, and mechanistic conclusions are drawn.
Reduced Representation of Second Virial Coefficients by Straight Lines
Authors: Kerl K. 
Published: July 2012

AbstractThe possibility of reduced representation of second virial coefficients B(T) by different straight lines Y = C ‐ DX (Y ≡ B/Vc, X ≡ (Tc/T)2) in the temperature ranges 1 (Tc), 2(TCTB) and 3 (TBT) is proposed (Tc, Vc = critical constants, TB = Boyle temperature). This concept is checked for 33 very different substances including the noble gases, dipole and quadrupolar gases, metal vapours (K, Na, Cs, Hg) and hydrocarbons with different bonding types.
Dielectric Study of Fractal Clusters Formed by Aqueous Nanodroplets in Apolar Media
Authors: Eicke Hans‐Friedrich , Geiger Simon , Sauer Friedrich A. , Thomas Harry 
Published: July 2012

AbstractDielectric investigations of fractal cluster formation near the percolation threshold were carried out on water‐in‐oil microemulsions consisting of water, Aerosol OT, and isooctane. Temperature‐dependent dielectric relaxation measurements in the frequency range 100 kHz to 1 GHz reveal the formation of fractal clusters as the percolation threshold is approached. The degree of ramification of the fractal clusters is phenomenologically characterized by a swelling factor. A repeated application of Bruggeman's unsymmetrical effective‐medium theory yields an internally consistent first‐order approximation which describes satisfactorily the characteristic features of the experimental results.
From Micellar Solutions to Microemulsions—A Kinetic Study
Authors: Hoffmann H. , Platz G. , Ulbricht W. 
Published: July 2012

AbstractThe influence of various additives like alcohols and hydrocarbons on the dynamic and structural properties of surfactant solutions with rodlike micelles was studied. It was observed that short chain alcohols and aliphatic hydrocarbons transform the rodlike micelles to globular aggregates while aromatic and alicyclic hydrocarbons and long chain alcohols have little effect on the size of the rods. Short chain alcohols accelerate very much the reequilibration processes in the micellar solutions and the chemical relaxation time can become shorter than the correlation time which is measured by the dynamic light scattering method. Solubilization of aliphatic hydrocarbons in such systems leads to longer chemical relaxation times. As a consequence the chemical relaxation time in these four component systems which can be called microemulsions is found to be longer than the correlation time.
Mechanisms of By‐Product Formation in the Dehydrochlorination of 1,2‐Dichloroethane
Authors: Schneider M. , Wolfrum J. 
Published: July 2012

AbstractThe decomposition of 1,2‐dichloroethane (DCE) to vinyl chloride (VC) was studied in the temperature range 620–750 K at DCE partial pressures of 50–450 Torr. Initiation of the radical chain reaction by a XeCl laser allowed controlled degree of conversion which had a strong influence on the formation of the major by‐products acetylene and 2‐chlorobutadiene. Both compounds are formed via abstraction of olefinic hydrogen from vinyl chloride by Cl atoms. Analysis of the product distribution combined with calculations yielded kinetic data of these side reactions. The mechanism was confirmed by adding HCl and vinyl chloride to the substrate. Formation of other byproducts by homogeneous processes and the photolysis of vinyl chloride are discussed.
Solvent Influence on (Perylene…Ag+)* Exciplex Fluorescence
Authors: Läufer Albrecht G. E. , Dreeskamp Herbert 
Published: July 2012

AbstractQuenching of perylene fluorescence by AgClO4 and concomitant perylene…Ag+*) exciplex formation was studied in 15 organic solvents ranging in dielectric constants from 6 to 65 and in mixed aqueous organic solvent systems. In almost all of these solvents perylene fluorescence quenching and exciplex fluorescence occurred.—The maximum of the exciplex emission spectrum lay at 490 ± 5 nm independent of the solvent employed. Distinct variations of the extent of fluorescence quenching and of exciplex formation with nature of solvent were found. They are interpreted in terms of (i) solvent viscosity (ii) coordination between solvent and Ag+ ion and (iii) solvent structure due to the Ag+ ion solvation.
On the Mechanism of the Cathodic Reduction of Anthraquinone to Anthrone
Authors: Beck F. , Heydecke Gabriele 
Published: July 2012

AbstractThe cathodic reduction of anthraquinone in 85% H2SO4 at cathodes of glassy carbon or mercury has been investigated. Voltammetric curves exhibit two steps at +0.23 and +0.10 V vs. SHE. The limiting current densities show a ratio between 4:0 via 1:1 to 1:3, depending on the experimental conditions. Experiments at the RRDE indicate two reoxidizable intermediates.—We derive a mechanism from our Findings, involving the electrochemical formation of these intermediates, anthrasemiquinone AQH2 and anthrahydroquinone AQH·. Both are subject to a bimolecular follow up reaction (disproportionation) to yield AQH2 and anthrone. The rate constants are estimated to be 2 · 103 and 3 · 104 1 mol−1 s−1, respectively. Anthrone is the only reduction product which could be isolated.
Thermodynamic investigations on cuprous selenide
Authors: Mostafa S. N. , Selim S. R. , Soliman S. A. , El‐Lakwah F. A. 
Published: July 2012

AbstractThe thermodynamic properties of electrons in cuprous selenide was studied with the help of coulometric titrations, using the solid state galvanic cell. ‐ Pt/Cu/CuBr/Cu2‐δSe/graphite, in the temperature region between 350 and 450°. The electromotive force (emf) of this cell was measured as a function of the stoichiometry of the selenide compound and the temperature. Analysis of the experimental data shows that the semiconducting properties of cuprous selenide and the change of the thermodynamic quantities with composition are only given by a change of the respective quantities of the defect electrons or of the quasifree electrons. From the electrochemical measurements besides of other quantities —the band gap energy can be calculated and is of about 0.39 eV.
An Experimental Setup for X‐ray Investigations on Higher Ordered Liquid Crystals
Authors: Klämke W. , Fan Z. X. , Haase W. , Müller H. J. , Gallardo H. 
Published: July 2012

AbstractX‐ray studies on microdomains of liquid crystals with higher ordered smectic phases require a technique providing a relative high resolution of the X‐ray reflexes. A diffractometer technique for such X‐ray investigations on liquid crystals and also a special oven, containing permanent magnets for getting aligned microdomains, is described. Some examples for the application of this technique on bulk samples and free standing films are discussed.
Options‐based HRM, intellectual capital, and exploratory and exploitative learning in law firms' practice groups
Authors: Kang Sung‐Choon , Snell Scott A. , Swart Juani 
Published: July 2012

AbstractThe current study intends to uncover the strategic contribution of human resource management by introducing a unique construct of options‐based (vis‐à‐vis project‐based) HRM and examining its links to intellectual capital and exploratory and exploitative learning in the context of law firms' practice groups. Empirical results show that options‐based HRM is positively related to the practice group's explorative and exploitative learning. The intellectual capital mediates the relationships between options‐based HRM and the practice group's learning for exploration and exploitation. This study makes a valuable contribution to the HRM literature by establishing the mechanisms by which HRM enables organizational learning and extending the scope of HRM research to professional service firms. Our findings also provide valuable implications for the literature of organizational learning. © 2012 Wiley Periodicals, Inc.
Reverse mentoring at work: Fostering cross‐generational learning and developing millennial leaders
Authors: Marcinkus Murphy Wendy 
Published: July 2012

AbstractReverse mentoring is an innovative way to encourage learning and facilitate cross‐generational relationships. It involves the pairing of a younger, junior employee acting as mentor to share expertise with an older, senior colleague as mentee. The purpose is knowledge sharing, with the mentee focused on learning from the mentor's updated subject or technological expertise and generational perspective. In addition, there is an emphasis on the leadership development of the mentors. Reverse mentoring is situated in the mentoring literature as an alternative form of mentoring, with unique characteristics and support functions exchanged that distinguish it from other developmental relationships. A model is developed that focuses on key variables to consider and how reverse mentoring may benefit individuals and organizations. Generational differences are also presented, and the ways in which reverse mentoring capitalizes on millennial capabilities and preferences are highlighted throughout. Finally, theoretical and practical contributions are discussed, including essential components for creating a reverse mentoring program. © 2012 Wiley Periodicals, Inc.
The valence and Rydberg excited states of CH2: A theoretical exploration
Authors: Li Bu‐Tong , Wei Zi‐Zhang , Wu Hai‐Shun 
Published: July 2012

AbstractUsing the completed active space second‐order perturbation (CASPT2) method, valence and Rydberg excited states of CH2 molecule are probed with the large atomic natural orbital (ANO‐L) basis set. Five states are optimized and the geometric parameters are in good agreement with the available data in literatures, furthermore, the state of 21B1 is obtained for the first time. Valence and Rydberg excited states of CH2 are also calculated for the vertical transitions with the ANO‐L+ basis set that is constructed by adding a set of 1s1p1d Rydberg orbitals into the ANO‐L basis set. Two Rydberg states of the p̃3A2 and r̃3B1 at 9.88 and 10.50 eV are obtained for the first time, and the 3a1 → 3dyz nature of the state p̃3A2 and the 3a1 → dx2−y2 nature of the state r̃3B1 are confirmed. © 2012 Wiley Periodicals, Inc.