bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating UV/H2O2 exposure as a DEHP degradation treatment for plasticized PVC
Authors: Hankett Jeanne M. , Welle Alexander , Lahann Joerg , Chen Zhan 
Published: March 2014

ABSTRACTMillions of tons of plasticized poly(vinyl chloride) (PVC) materials are disposed every year. A biologically sustainable and green method for removal of toxic plasticizers from polymer systems after disposal is highly desired since plasticizers can leach out into the environment over decades. Here we compare the surface and bulk structural changes of DEHP‐plasticized PVC after two treatments intended to degrade bis‐2‐ethylhexyl phthalate (DEHP) in PVC plastic: short wave (254 nm) UV with and without the addition of 35 wt % H2O2. Sum frequency generation vibrational spectroscopy (SFG) reveals the addition of aqueous H2O2 decreases CH3 signals on the surface of the films up to 8 h, due to increased molecular disorder and the removal of alkyl chains. Secondary ion mass spectrometry demonstrates that the degradation of DEHP after 8 h of reaction is similar with and without the use of H2O2. However, FTIR results reveal that the introduction of H2O2 reduces bulk DEHP degradation and leads to competing radical chain scission reactions with PVC. Therefore, simple short wave UV exposure may be an effective means to degrade DEHP within and on PVC plastic and the addition of H2O2 is only beneficial if additional degradation of PVC is needed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40649.
Steady State Photocapacitance Study of Semiconductor/Aqueous Electrolyte Junctions: I. Interest and Difficulties in the Case of n‐GaAs
Authors: Allongue P. , Cachet H. 
Published: March 2014

AbstractThe photocapacitance (PC) technique allows the determination of deep‐level as well as surface states at semiconductor/electrolyte (SC/EL) contacts. Expressions of the PC signal, given in several peculiar cases, help in the understanding of the results obtained with GaAs in contact with an aqueous electrolyte. It is found that relevant experimental conditions of band bending and/or incident photon flux are required to detect transitions which have a small magnitude compared to the large response due to EL2 in GaAs. A quantitative interpretation of the spectrum is also given.
Dielectric Spectroscopy on Aqueous Solutions of Purine and 6‐Methylpurine
Authors: Kaatze U. , Schmidt P. , Pottel R. 
Published: March 2014

AbstractBetween 1 MHz and 40 GHz the complex (electric) permittivity of aqueous solutions of purine and 6‐methylpurine has been measured as a function of frequency for various solute concentrations. Different relaxation spectral functions are fitted to the measured spectra to yield the solvent contribution to the static permittivity, the dipole moment of solute, the principal dielectric relaxation time of the solvent water, the number of hydration water molecules per molecule of solute, the hydration water relaxation time, and the relaxation time of solute. Unexspectedly, no effect of self‐association of the purine bases is found in these parameters.
ESR Analysis of Tetrahedral AB2C4 Defect Compounds with Mn2+ Ions as Spin Probes
Authors: Siebert D. , Febbraro S. 
Published: March 2014

AbstractThe ESR spectra of Mn2+ in eight defect tetrahedral structures have been analysed. The values for g and the hyperfine constant A turn out to be very close to those in the binary analogs with the same anion. As for the sulfides there is poor agreement between the measured and calculated b02 values, if one evaluates these values according to the superposition model of Newman and Urban using the unperturbed positions of the ligands. For some selenides and the telluride linewidths greater than 2.2 mT in the central sextets were observed and assigned to different degrees of disorder in the cation sublattices in agreement with recent X‐ray investigations.
Anisotropy of Translational Diffusion in Liquid α,ω‐Dibromoalkanes
Authors: Kempka M. , Peplińska B. , Pajak Z. 
Published: March 2014

AbstractThe analysis of the measured temperature dependences of self‐diffusion coefficients for prolate ellipsoid type molecules of α,ω‐dibromo‐methane, ‐ethane, ‐octane, ‐decane and ‐dodecane performed in the frame of the modified Perrin model enabled to discover anisotropy of translational diffusion in liquids. On the basis of the Eyring theory the effect was confirmed and the jump length of about 7 Å for all the molecules was derived. The same jump length for longer molecules was obtained from the Cohen‐Turnbull free volume theory.
A Fourier Transform Impedance Spectrometer using Logarithmically Spaced Time Samples
Authors: Ühlken Jürgen , Waser Rainer , Wiese Harm 
Published: March 2014

AbstractA Fourier transform impedance spectrometer is described which is based on a transform algorithm using logarithmically spaced time samples. Thereby, the computational effort of Fourier transformation, which in electrochemistry constitutes the main problem of the application of the Fourier transform method, is substantially reduced. The spectrometer permits the performance of impedance measurements in the frequency range from 1 Hz to 105 Hz within a few seconds. Moreover, the impedance spectrometer mainly consists of devices, which are commonly available in electrochemical laboratories (e.g., microcomputer, storage oscilloscope, potentiostat).
Thermal Conductivity of Benzene and Cyclohexane under High Pressures
Authors: Tanaka Y. , Hase T. , Kubota H. , Makita T. 
Published: March 2014

AbstractThe thermal conductivity of benzene and cyclohexane has been measured by a transient hot‐wire method in the temperatue range from 283–373 K under pressures up to 250 MPa or freezing pressures with an estimated uncertainty of ±1.0%. The thermal conductivity of each substance decreases almost linearly with rising temperature at a constant pressure, and increases with increasing pressure at a constant temperature. The absolute value of the temperature coefficient of the thermal conductivity, (∂λ/∂T)P decreases with increasing pressure. The pressure coefficient (∂λ/∂P)T increases with rising temperature. The thermal conductivity obtained are correlated with temperature and pressure by a similar expression to the Tait equation. The dense hard‐sphere model presented by Menashe et al. also provides good representation of the present experimental results.
The Binary System Benzene‐Hexafluorobenzene Studied by SSOZ Theory and Computer Simulation II. The Structure of the Pure Components
Authors: Steinhauser O. , Hausleithner I. 
Published: March 2014

AbstractThe atom‐atom correlation functions (AACFs) of the respective pure components C6H6 and C6F6 are thoroughly analysed by means of SSOZ (site‐site Ornstein‐Zernike) theory and computer simulation. In particular, appropriate linear combinations of the AACFs are contrasted to experimental scattering data. This comparison shows the necessity of a potential refinement, which is done by an optimization of the static lattice structure and the harmonic frequencies. With this optimized potential further simulation studies are performed and the respective linear combinations of the improved AACFs agree now very well with the experimental quantities.
Die Auflösung yon Zinkmetall und die Löslichkeit von Zinkhydroxid durch Messung der elektrischen Leitfähigkeit im System Zink/Wasser
Authors: Bohnsack G. 
Published: March 2014

AbstractIn conjunction with colorimetric determination of zinc concentration, sensitive conductivity measurement in solutions consisting of flowing deionized water saturated with hydroxide‐covered metallic zinc enabled conclusions to be drawn regarding the composition of the solutions. The equivalent conductivities of the ions and of a series of solutions allowed us to determine the ion concentrations of the solutions and the degrees of dissociation. In this way the non‐ionic portion was defined also. We thus acquired reliable data for determining the solubility of zinc hydroxide and zinc oxide in water as the sum of the dissolved components. These solubilities are lower than those given in the literature so far. The data can be used to calculate the normal thermodynamic constants, which agree well with the known values. As we were able to determine the undissociated zinc hydroxide in solution fairly reliably, it has also been possible for us to state the first dissociation constant of zinc hydroxid
Dynamic Light Scattering of the Fluid‐Fluid Phase Transition in the Vicinity of the Critical Solution Point and in the First Order Transition Region
Authors: Schröer W. , Rybarsch C. , Strojny M. , Staude W. 
Published: March 2014

AbstractMeasurements of the Rayleigh‐Brillouin spectra of the binary system nitroethane‐isooctane have been carried out as function of temperature and concentration. The purpose of this investigation was to study the transition of one type of phase transformation to an other. Taking the temperature as variable, the phase transformation is of second order for one specific concentration – the critical concentration, whereas for other concentrations it is of first order. Samples deviating up to 20% from the critical composition have been investigated in the temperature range 10 to 10−3 K above the transition temperature in the homogeneous region. The temperature dependence of the Rayleigh‐Brillouin intensity ratio Ir/2Ib can be described by the same critical exponent γ = 1.24 for all concentrations provided the critical temperature in the scaling function is replaced by another reference temperature, interpreted as pseudo‐spinodal temperature T*s The concentration dependence of T*s is found to be |X – Xc| = A · Tβ*s, where ts is the reduced temperature ts = 1 –T*s/Tc. The value of the exponent is found to be β* = 0.5, which is the classical exponent of the spinodal curve.
Fluorescein‐Labelled Glucagon: A New Probe for the Study of Receptor Disposition in Membranes
Authors: Cantrill Richard C. , Ward Larry W. , Heithier Helmuth , Klein Helmut W. , Peters Reiner , Helmreich Ernst J. M. 
Published: March 2014

AbstractNew fluorescent glucagon derivatives were synthesized by converting tryptophan25 to 2‐thiol‐tryptophan with the consequent use of thiol specific fluorescent reagents. All derivatives retained the ability to bind tightly to rat liver membranes and rat hepatocytes in primary culture and to activate adenylate cyclase as potently as native glucagon. Thus these derivatives are full agonists. From experiments with monolayer cultured hepatocytes and 125I‐glucagon at elevated temperatures it was assumed that the ligand was internalised at this temperature since some of the specifically bound ligand could no longer be washed off with acid. This was confirmed in experiments where monolayer cultures of hepatocytes were incubated with the fluorescein‐labelled derivates of glucagon, thus allowing the study of the distribution of glucagon specifically bound on the cell surface using video intensification microscopic techniques. In keeping with autoradiographic studies using radiolabelled glucagon, or electron microscope studies using ferritin labelled glucagon, we could now show using fluorescently labelled glucagon derivatives and video intensification microscopy that at lower temperatures the bound ligand was distributed all over the cell surface. Whereas, at the higher temperature, ligand derived fluorescence could only be detected in mobile intracellular vesicles following internalisation and removal from the cell surface.
Structure and Membrane Permeability of Charged Molecules: Membrane Experiments with Tetraphenylborate Analogs
Authors: Benz Roland 
Published: March 2014

AbstractCharge‐pulse experiments were performed on membranes made of dioleoyl phosphatidylcholine/n‐decane in the presence of 4 structural analogs of tetraphenylborate (TPB, triphenylcyanoborate (TPCB), tetrakis (4‐fluorophenyl)borate (TFPB), tetrakis (4‐chlorophenyl)borate (TCPB), and tetrakis (3‐trifluoromethylphenyl)borate (TTFPB)). The analysis of the experimental results using a previously proposed model allowed the calculation of the partition coefficient, β, and of the translocation rate constant, ki, of the lipophilic ions. The adsorption of the different TPB‐analogs to the membranes was similar, whereas their structure had a dramatic influence on the translocation rate constants and they increased by almost six orders of magnitude from TPCB to TTFPB. The free energy of the ions in the membranes as calculated from the translocation rate constants, decreased from TPCB to TTFPB by about 31 kJ/mol (7.4 kcal/mol). The change of the free energy in the membrane was used for the estimation of an effective radius of the TPB‐analogs with respect to the van der Waals radius of TPB.
Dissipative Structures of Ion Channels in the Fluid Mosaic Model of a Membrane Cable
Authors: Fromherz Peter 
Published: March 2014

AbstractThe dynamics of an ideal fluid mosaic of ionic ion channels in a membrane is combined with the dynamics of the electrical membrane potential. The distribution of the channels and the profile of the potential in a linear cable are described by two coupled nonlinear partial differential equations: A Smoluchoswki equation with respect to lateral diffusion and electrophoresis of the channels and Kelvin's cable equation with respect to the propagation of the potential. Numerical integration demonstrates the formation of periodic patterns far from electrochemical equilibrium.
Stereodynamic Coupling of Light Energy and Ion Transport in the Retinal Proteins Bacteriorhodopsin and Halorhodopsin
Authors: Tavan Paul 
Published: March 2014

AbstractThe status of research on chromophore‐protein interactions in the light‐driven ion pumps bacteriorhodopsin and halorhodopsin is reviewed. The ideas of the socalled 13,14‐cis model, which consider retinal as an ion switch, and corresponding experimental checks are particularly emphasized.
Pressure Dependence of the Rotational Relaxation of t‐Stilbene and t‐Diphenylbutadiene in n‐Alkanes
Authors: Schroeder J. , Schwarzer D. , Troe J. 
Published: March 2014

AbstractThe rotational relaxation of t‐stilbene and t‐diphenylbutadiene in the first electronically excited singlet state was measured by picosecond anisotropic absorption spectroscopy. The viscosity η in n‐alkane solvents was changed by increasing the pressure up to several kilobars. In all cases the viscosity dependence of the rotational relaxation time τor could be described by a modified form of the Stokes‐Einstein‐Debye equation. No solvent dependence was found for η ≤ 0.8 cP. Therefore we attribute the observed solvent dependence of photoisomerisation rates of t‐stilbene and t‐diphenylbutadiene measured under the same conditions to specific solvent‐solute interactions that modify the path on the potential energy surface.
The Kinetics of the Reaction of N2(A3Σu+) with NO2(X̃2A1)
Authors: Böhmer E. , Hack W. 
Published: March 2014

AbstractThe reaction of N2(A3Σu+) with NO2(X̃2A1) was studied in a fast discharge flow system. N2(A) was produced by energy transfer from Ar* and detected by laser induced fluorescence (LIF). From the N2(A,ν′)‐depletion as a function of reactant concentration under pseudo‐first order conditions [N2(A)]0 ≪ [NO2] the overall reaction rate constants for the reactions:

were determined: k10 = 0.76, k11 = 0.84, k12 = 1.8 and k13 = 1.8 (in 1013 cm3/mol·s) at T = 298 K. – The reaction products NO(X2Π) and O(3P) were detected directly by LIF via the transition (A2Σ+ – X2Π) and with resonance absorption (RA) respectively. Other products than NO(X) and O(3P) were not detected. The absolute NO concentration was calibrated with a NO/Ar mixture. The NO(X) concentration at long reaction times was found to be equal to the [N2(A)]0 concentration within the experimental error limits, i.e. the branching ratio for the reaction:magnified imagewas determined to be unity. The reaction of N2(A) with NO2(X̃) can thus be used as a calibration reaction to determine absolute N2(A) concentrations.
A Model for the Electrochemical Behaviour of TiN and TiC
Authors: Schmickler Wolfgang , Schultze J. W. 
Published: March 2014

AbstractWe have performed simple model calculations for the surface electronic structure of TiN and TiC based on the theory of Miedema for the heat of formation of these compounds. The electronic properties of pure anionic (N‐ and C‐surfaces) and pure cationic (Ti‐) surfaces are contrasted. The anionic surfaces have a higher surface energy, and cannot screen external fields as well as the cationic surfaces. Our model suggests that at potentials below the onset of oxidation surface layers enriched in nitrogen (resp. carbon) are formed, which shield the underlying titanium atoms from the external field. At higher potentials the field can penetrate through the anions at the surface and induce the oxidation of the titanium atoms.
Dynamics of Nitrite Ions in Ionic Plastic Crystal RbNO2 Studied by Nitrogen and Rubidium NMR
Authors: Honda Hisashi , Kenmotsu Motoko , Ohki Hiroshi , Ikeda Ryuichi , Furukawa Yoshihiro 
Published: March 2014

AbstractTemperature dependences of NMR spin‐lattice relaxation times T1, of 15N, 14N, 85Rb and 87Rb, spin‐spin relaxation times T2 of 14N and 87Rb, and NMR spectra of 15N and 87Rb in RbNO, were observed in the plastic phase (Phase 1) and the low‐temperature phase (Phase II) obtainable below 264 K. We showed the presence of a new NO−2 motion in Phase II with an activation energy of 12‐ 15 kJ mol−1. This motion was assigned to NO−2 reorientation about its C2‐axis by referring to the temperature dependence of the 15N chemical‐shift anisotropy and the reported data of the dielectric dispersion. In the plastic phase, we detected the NO−2 isotropic reorientation with an activation energy of 6.2 kJ mol−1 and the ionic self‐diffusion with 110 kJ mol−1, which was confirmed by measuring electrical conductivity.
Study of Sodium Colloids in Heavily Irradiated NaCl Crystals by Nuclear Magnetic Resonance
Authors: Kanert O. , Schmidt C. , Küchler R. , Den Hartog H.W. 
Published: March 2014

AbstractStrong irradiation of NaCl crystals results in a formation of sodium colloids which exhibit metallic properties. In consequence, besides the 23Na line of NaCl a second well‐separated 23Na line occurs in the NMR spectrum caused by the Knight shift of the conduction electrons. We present Knight shift and nuclear spin relaxation measurements performed on the “metallic” 23Na line in e–‐irradiated NaCl single‐crystals between about 4 and 390 K. Evaluation of the data leads to detailed information on the electronic properties, atomic self‐diffusion, and melting behavior of the colloids. The results are discussed in view of corresponding data obtained in bulk sodium.
On the Interaction of Paramagnetic Point Defects in Heavy Metal Fluoride Glasses
Authors: Scholz G. , Stösser R. , Grande T. , Aasland S. 
Published: March 2014

AbstractThe origin and nature of ESR signals of fluoride glasses (ZBLAN: ZrF4/BaF2/LaF3/AlF3/NaF) doped both with Fe3+ and Fe2+ ions was studied using the temperature and microwave power (PMW) dependencies as well as a complete simulation of the X‐band ESR spectra. For the first time, evidence is given for the existence of {FeII‐OH‐FeIII} units (S' = 9/2) formed in the glasses involving traces of O2 and H2O present in the samples. Fluoride glassy matrices constrain the formation of interacting species and therefore nonuniform spatial distributions of the dopants. Reasons are seen (i) in the local structural chemistry (geometrical and charge compensation reasons), and (ii) in the melting and post‐melting processes.
Thermochemistry of the NaBr‐Nal Solid Solution at 750 K – A Knudsen Effusion Mass Spectrometric Study
Authors: Miller Miroslaw , Hilpert Klaus 
Published: March 2014

AbstractThe excess molar Gibbs energy and partial pressures at a temperature of 750 K for the solid phase of the NaBr‐NaI system were determined by Knudsen effusion mass spectrometry. The parameters of the Redlich‐Kister equation for GEm resulted in kJ mol−1 as B1 = 6.46 and B2 = −1.12. The thermodynamic data obtained from the molecular ion intensities of NaBr+ and NaI+ and those obtained from the fragment ion intensities of Na2Br+ (from Na2Br2) and Na2I+ (from Na2I2) agree well. The results of this work are discussed with respect to those reported by other authors.
Viscosity Measurements on Molten Salts with an Oscillating Cup Viscometer: Viscosity of Molten KNO3 and NaCl
Authors: Tolbaru D. , Borcan Rodica , Zuca Stefania 
Published: March 2014

AbstractAn oscillating cup viscometer interfaced to an automatic data acquisition and processing system (computer, interface, software) was built for viscosity measurements in molten salts below 1400 K.In order to avoid the “meniscus effect”, the main source of errors of the method, the measurements were carried out in the so‐called “full cup” condition, i.e. with the height of the liquid column (h) of 11.2 cm, the overall height of the cup being 11.9 cm. An adequate software supplied η values at each temperature, as function of R, I, δ, h, ρ and T values in air and with liquid containing cup. The viscosity of molten KNO3 and NaCl, both of “standard salt purity”, was reinvestigated over a temperature range of 100 K above their melting points. The standard deviation of the data obtained was ±0.38%. These data were systematically lower (3% for ηNaCl and 2% for η) than those obtained earlier by the same method, but agree within ±0.9% with the recommended Janz's “calibration quality viscosity data”.One can conclude that the method gives accurate results only if operated in “full cup” condition.
The Rovibrational Overtone Spectrum of H13CNO up to 3600 cm−1: A Network of Resonance Systems
Authors: Albert Sieghard , Albert Karen Keppler , Winnewisser Manfred , Winnewisser Brenda P. 
Published: March 2014

AbstractThe infrared spectrum of fulminic acid, H13CNO, has been analyzed in the range 700–3600 cm−1. More than 90 new vibrational levels have been identified. Power series coefficients of these levels are given.Every vibrational level and its rotational levels are locally or globally perturbed. It was possible to classify most of the interactions into a grand network of Coriolis‐ and/or Fermi‐type resonance systems, similar to that described for the parent species H12CNO, by using the previously known basic resonance systems 00010/00002 and 00100/00004. In addition, as for H12CNO, another basic resonance for H13CNO was identified as 01000/00111, leading to the system 00015/01000/00103/(00111), corresponding to a resonance involving the same states in the parent species. As a consequence of the interactions, many so‐called “resonance‐enhanced” rovibrational subbands have been assigned. The identification and partial analysis of the resonance systems have been carried out, first with the help of different representations of reduced term values and second, by determining the J‐value separation between e and f crossing points. The five main resonance systems will be discussed in this paper.
The Thermal Decomposition of NH2 and NH Radicals
Authors: Deppe J. , Friedrichs G. , Ibrahim A. , Römming H.‐J. , Wagner H. Gg. 
Published: March 2014

AbstractThe formation of NH2 and NH radicals as well as H and N atoms during the thermal decomposition of hydrazine was investigated over a wide temperature range. For the first time frequency‐modulated spectroscopy was used for the detection of NH2 radicals behind shock waves. In comparison with the dual beam laser absorption technique, the detection limit has been improved by one and a half orders of magnitude.For reaction (5a) NH2 + M → NH + H + M the rate constants were obtained in the temperature range from 2200 to 4000 Kk5a = (1.2 ± 0.5)1015 · exp[‐(318±10) kJ mol−1/RT] cm3/mol sand for reaction (6) NH + M → N + H + M in the temperature range from 2500 to 3400 Kk6 = (1.8 ± 0.8)1014 · exp[‐(313 ± 15)kJ mol−1/RT] cm3/mol s.The experimental apparent activation energies were found to be in good agreement with theoretical calculations and recently recommended enthalpies of formation for NH2 and NH. The competing NH2 decomposition channel (5b) NH2 + M → N + H2 + M was shown to be of minor importance (⩽ 5%). The kinetic behavior of the unimolecular decomposition of NH2 is compared with that of H20 and 3CH2.