bluuebunny/crossref_metadata_2025 huggingface dataset:
Fourier Transform Microwave Spectroscopy – An Improved Tool for Investigation of Rotational Spectra
Authors: Dreizler Helmut
Published: March 2014

Like in other fields of spectroscopy, the introduction of Fourier transform techniques promoted microwave and millimeter wave rotational spectroscopy of molecular species. As the time scale is shorter than in nuclear magnetic resonance, the development had to wait for sufficiently fast instrumental components for this time domain spectroscopy. By investigation of static molecular gases in waveguide sample cells and of molecular species in a pulsed supersonic beam, the Fourier transform technique has greatly enhanced the potential of rotational spectroscopy. The field is still open for further improvements.

The basic theory and the present state of the experiments will be given and illustrated by examples of investigated species.
HCN Clusters in Molecular Beams and Cryogenic Matrices
Authors: Beichert P. , Pfeiler D. , Knözinger E.
Published: March 2014

Cluster formation of hydrogen cyanide (HCN) was traced by mass spectroscopy in molecular beams and by FTIR spectroscopy in cryogenic matrices in which the clusters were embedded. Both experiments provided evidence for the presence of linear (n ≥ 2) and cyclic structures (n ≥ 3) which were predicted by ab initio calculations as comparably stable.

The mass spectra clearly reflect a fundamentally different behaviour of the two types of clusters within the expansion zone: the linear species exhibit the cabability of cluster growth, while the cyclic ones do not. This leads to a characteristic size distribution with two marked maxima. During matrix deposition, considerable distortions of the clusters are created which may be healed out by annealing. The resulting sharp bands in the CH stretching region were assigned in agreement with ab initio calculations and previous IR studies aiming at small linear and cyclic species (n ≤ 3) in diverse liquid and solid environments.
Influence of Cholesterol and β‐Sitosterol on the Dynamic Behaviour of DPPC as Detected by TMA‐DPH and PyrPC Fluorescence: A Fluorescence Lifetime Distribution and Time‐Resolved Anisotropy Study
Authors: Bernsdorff C , Winter R. , Hazlett T.L. , Gratton E.
Published: March 2014

Fluorescence lifetime and time‐resolved anisotropy measurements on 1‐(4‐trimethylammonium‐phenyl)‐6‐phenyl‐1,3,5‐hexatriene (TMA‐DPH) and 1‐palmitoyl‐2‐[10‐(1‐pyrenyl)decanoyl]‐phosphatidylcholine (PyrPC) in lipid vesicles of 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphatidylcholine (DPPC) with and without cholesterol and β‐sitosterol, using multifrequency cross‐correlation phase fluorometry, are presented. We used TMA‐DPH and PyrPC as fluorescence probe for detecting rotational dynamics. Contrary to TMA‐DPH, which is tethered to the bilayer interface and therefore detects wobbling rotational dynamics in the interfacial and headgroup region, PyrPC senses the deeper acyl chain dynamics of the lipid bilayer. We have investigated the influence of sterol structure on the lipid dynamics. The experiments were carried out at two temperatures, one below and one above the main phase transition temperature of DPPC. Data were analyzed in terms of Lorentzian distribution functions for the fluorescence lifetime results and in terms of hindered rotation for the time‐resolved anisotropy results. We noticed, that addition of cholesterol and β‐sitosterol results in a distinct increase in average fluorescence lifetime of TMA‐DPH in both lipid phases. The rotational rates of TMA‐DPH depolarizing motions are only modestly increased in going from the gel to the liquid‐crystalline phase of DPPC. However, a marked increase in the contribution of fast rotational motions of TMA‐DPH is found as the temperature is increased through the main transition. No significant differences in rotational rates of TMA‐DPH exist between samples with embedded cholesterol or β‐sitosterol at T = 55°C. The rotational rate of TMA‐DPH in the gel state of the lipid bilayer at T = 35°C is slightly larger in the case of β‐sitosterol, however. Cholesterol and β‐sitosterol, then, have a similar effect on the contribution of fast rotational dynamics in the interfacial region of the bilayer. It decreases about 40% upon addition of 50 mol‐% sterol. The incorporation of either sterol into DPPC vesicles leads to an increase in fluorescence lifetime of PyrPC in both lipid phases. The rotational rates of PyrPC in the bilayer are an order of magnitude smaller than those of TMA‐DPH. Also the contributions of fast rotational motions significantly differ for the two fluorophores. The motional freedom in the deeper acyl chain region of DPPC in its fluid‐like state at T = 55°C is scarcely affected by addition of either sterol. However, differences in the rotational rates of the two sterols are observed for high sterol concentrations.
Subpicosecond‐Pulse‐Laser‐Induced Electron Emission from Mercury and Silver into Aqueous Electrolytes
Authors: Krivenko A.G. , Krüger J. , Kautek W. , Benderskii V.A.
Published: March 2014

Highly efficient superlinear electron emission from liquid mercury and polycrystalline silver electrodes into aqueous electrolyte solutions has been discovered. The effect is induced by visible subpicosecond‐laser pulses (300 fs) with a photon energy (h v ≈ 2 eV; 615 nm) less than the threshold of the linear photoeffect. The charge density q emitted from mercury by 615‐nm laser pulses increased from 10−9 to 10−5 C cm−2 in the intensity range 7 = 4–30 GW cm−2. At silver, 10−9 to 10−7 C cm−2 were generated in the range of I = 7–70 GW cm−2. The charge density grew with the concentration of electron acceptors (H3O+ and CHCl3) at I < 20 GW cm−2, because the capture of emitted electrons prevents them from returning to electrode surface. The subsequent slow electron reduction of the electron capture products (H‐atoms and CHCl2‐radicals, respectively) indicates the laser‐induced electron transfer across the interface. Ultraviolet 300‐fs‐pulses (h v ≈ 4 eV) at intensities I < 6 GW cm−2 lead to effective quantum yields corresponding to one‐photon emission. This emission disappeared at Hg when 6‐ps‐pulses were applied with the same energy, but still occurred at Ag. These results conform with theoretical predictions of charge‐intensity dependencies, pulse duration and electrode potential characteristics for thermoelectron emission of a nonequilibrium electron gas from metals into electrolyte solutions.
Festkörperelektrolytpotentiometrie an oxidischen Katalysatoren
Authors: Brück Johannes , Brust Monika , Lintz Hans‐Günther
Published: March 2014

The oxygen activity in the solid determines the phase composition which should be stable in the case of oxygen transfer reactions at oxidic catalyst. Its value results from the rates of the oxygen uptake by the solid and the oxygen transfer to an acceptor in the gas phase, e.g. a hydrocarbon or ammonia. This oxygen activity in the catalyst can be determined under reaction conditions with the aid of a potentiometric method based on the application of solid ion conductors. In that case the catalyst is simultaneously one electrode of an electrochemical cell, the oxygen activity and the reaction rate being measured simultaneously.

The method has been applied during the investigation of the reduction of nitrogen monoxide by ammonia on copper oxide and a typical SCR catalyst on the basis of vanadia‐titania. The reaction was studied in the domain 300 <ϑ/°C < 390 at reactant concentrations up to 4000 ppm, the oxygen content in the gas phase being varied between 0 and 10 Vol.%.

The results demonstrate unambiguously a correlation between oxidation state of the catalyst and the reaction kinetics. The rate increasing influence of oxygen is accompanied by the transition of V4+to V5+in the case of the SCR catalyst. In the case of copper oxide catalyst the reduction rate of NO is decreased at increasing oxygen concentration at the transition to Cu2+. In addition the increased N2O formation could be observed.

In spite of the high oxygen excess a quasiequilibrium of oxygen chemisorption can be excluded in any case.
Electrochemical Study of Zircaloy‐4 in Aqueous Sulphate Solution
Authors: Al‐Abdallah M.M. , Göhr H.
Published: March 2014

The surface of zircaloy‐4 electrodes was studied in 0.5 M K2SO4 solution by using impedance measurement as a function of potential and by polarization curves. Parameters of the faraday impedance, charge transfer and properties of passivation film were obtained. Faradayic impedance shows clear dependence on the applied anodic potential as well as on the time of polarization.
Investigations of the Reactions of 1CH2 (ã1A1 (v = 0,1)) with H2O, D2O and HCl
Authors: Carstensen H.‐H. , Wagner H. Gg.
Published: March 2014

The reactions of 1CH2(ã1A1) in its vibrational ground state (1CH2(v = 0)) and with single excited bending mode (1CH2(v = 1)) with the reactants H2O (1), D2O (2) and HCl (3) were investigated with a LIF apparatus under quasistationary and first order conditions. 1CH2 was produced via ketene photolysis at 308 nm (1CH2(v = 0) and 1CH2(v = 1)) and at 336 nm (only 1CH2(v = 0)). The evaluation of the kinetic data of 1CH2(v = 0) gave different results for both wavelength. At λ = 336 nm obtained rate constants were in general higher compared to those at λ = 308 nm. The measurements at λ = 308 nm therefore seem to be influenced by secondary processes and they do not give the ‘real rate constant’.

1CH2(v = 1) reacts faster with all three investigated reactants than 1CH2(v = 0) does. Vibrational deactivation with unusual high rate constants may explain these different reactivities of 1CH2(v = 0) and 1CH2(v = 1), but can only in part explain differences for the two 1CH2(v = 0) measurements.

The following rate constants were measured at T = 295 K (in cm3·mol−1·s−1): k1(1CH2(v = 0)) = (1.45 ± 0,1)·1014, k1(1CH2(v = 1)) = (2.3 ± 0.2)·1014, k2(1CH2(v = 0)) ≈ 1.1·1014, k2(1CH2(v = 1)) = (1.75 ± 0.15)·1014, k3(1CH2(v = 0)) = (2.0 ± 0.2)·1014, and k3(1CH2(v = 1)) = (2.2±0.2)·1014.

In the range from 255 K to 475 K the rate constants of the reactions of 1CH2(v = 0,1) with H2O and D2O show a significant dependence on temperature T which can be expressed by T−n with n = 0.6 to 0.8.

The channel of the reaction of 1CH2 + H2O leading to CH3 + OH was found to contribute 50±15% to the total reaction, thus being the main channel at p ≤ 14 mbar. Formaldehyde could not be detected as a product of (1).
An Investigation by Diffusion Layer Imaging of Coupled Homogeneous Chemical Reactions of the Benzophenone Radical Anion in N,N‐Dimethylformamide
Authors: Walczyk K.R. , Popkirov G.S. , Schindler R.N.
Published: March 2014

The electrochemical reduction of benzophenone (BP) to its primary radical anion BP− with coupled homogeneous chemical reactions was investigated in N,N‐dimethylformamide. Protonation of BP− with benzoic acid and with o‐cresol, respectively, used as proton donors, and disproportionation of BP− in the presence of excess Li+ ions were studied by DLI technique. Rate constants for protonation and disproportionation as well as equilibrium constants for ion association were evaluated. Possible reaction pathways, and the effect of ion association on the kinetic behaviour are discussed.
Surface Enhanced Raman Scattering from Acridine on Copper Electrodes at Low Adsorbate Concentration
Authors: Niaura G. , Malinauskas A.
Published: March 2014

Surface enhanced Raman spectra of acridine in a concentration range 6.7·10−9 to 3.6·10−3 M were obtained on a copper electrode in a chloride‐containing solution at pH 2.5. A conclusion was made that acridine adsorbs as an ion pair formed from acridinium cation and chloride anion. An adsorption isotherm for acridine on an activated copper electrode was obtained.
Rate Constants of the Reactions of CHCl (X̃1A′) with Ethylene, Propylene, and Acetylene
Authors: Carstensen H.‐H. , Rehbein C , Wagner H. Gg.
Published: March 2014

The rate constants of the reactions of CHCl (X̃1A′) with C2H2 (k4), C2H4 (k5) and C3H6 (k6) were measured as a function of temperature. Experiments were carried out under quasistationary conditions at around 18.5 mbar total pressure. It is shown that excimer laser photolysis of CF2 = CHCl at λPH = 193 nm is a suitable source for CHCl (X̃1A′) generation. The following rate constants were obtained from logarithm plots:

k4 = (4.2±0.1)·1012 (T/295K)−(0.79±0.06) cm3 mol−1 s−1

k5 = (3.2±0.2)·1012 (T/295 K)−(1.52±0.12) cm3 mol−1 s−1

k6 = (8.3±1.4)·1012 (T/295 K)−(1.39±0.05) cm3 mol−1 s−1

The reactivity of CHCl (X̃1A′) is compared to those of other carbenes.
The Density of Ammonia at High Pressures to 723 K and 950 MPa
Authors: Harlow A. , Wiegand G. , Franck E.U.
Published: March 2014

High pressure‐high temperature procedure and equipment is described to determine the specific volume of ammonia as a function of pressure and temperature. An autoclave consisting of a nickel‐based superalloy and a suitable pressure‐sensitive separator between ammonia and the pressure‐transmitting fluid is used. Ten volume isotherms between 298 and 723 K and at pressures from 10 to 950 MPa have been determined. Previous literature data extend to 950 MPa but only up to 473 or to 723 K at pressures below 500 MPa. Polynomials with up to eleven terms are used to represent each experimental volume isotherm with a maximum average deviation of 0.16%. A table with smoothed density values is presented for the whole range of conditions. A comparison with data calculated earlier by Haar and Gallagher (1978) up to 500 MPa showed deviations between 0.06 and 1.1% with an average of 0.4%. The present isothermal volume data are reasonably well described by Tait equations. Parameters are given.
Concentration‐Dependent Electroacoustic Spectra of Some Simple Alkali‐Halide Aqueous Electrolytes
Authors: Tankovsky N. , Bärner K.
Published: March 2014

Excitation of acoustic waves in electrolytes by means of a.c. electric fields has been used to examine the structural and dynamical properties of the solutions. The acoustical signal efficiency depends on the electrolyte concentration and on the frequency of the exciting electric field. Experimental results, obtained in the aqueous solutions of LiCl, NaCl and KCl, are discussed. The influence of the electroacoustic‐cell design on the obtained results is studied as well.
A Time Domain Reflectometer for Dielectric Relaxation Spectroscopy of Electrolyte Solutions
Authors: Buchner R. , Barthel J.
Published: March 2014

A time domain reflectometer for dielectric relaxation spectroscopy of electrolyte solutions in the temperature range of −;45 ≤ ϑ /°C ≤ 90 is presented. With a set of cutoff cells differing in their cell constants, pure solvents covering the permittivity range of 7 ≤ ϵ ≤ 228 and their concentrated electrolyte solutions (κ > 1 Ω−1 m−1) can be investigated at frequencies of 0.05 ≤ v/GHz ≤ 9. In combination with the transmission line system of our laboratory (8.5 ≤ v/GHz ≤ 89) dielectric dispersion, ϵ′(v), and total loss, η″(v) = ϵ″(v) + κ/(2π vϵ0) can be determined with 2% accuracy relative to ϵ.
Characterization of Mo Species Supported on SiO2 Modified with Be2+ and Mg2+
Authors: Aroni Phryni
Published: March 2014

Two series of modified carriers (m.c.) have been prepared by doping silica with various amounts of Be2+ and Mg2+. The prepared m.c. have been used as supports for the preparation of supported Mo(VI) oxide catalysts. The magnitude of interactions between SiO2 and Be2+ or Mg2+ nitrates depends on the kind and content of the cation. After calcination at 600°C a greater fraction of cations remains on the support surface as well dispersed M(NO2)2 in the case of Mg2+ m.c. Concerning the Mo containing samples it was found that doping by Be2+ and Mg2+ causes a solid state transformation of octahedral Mo(VI) to tetrahedral Mo(VI). As before, the extent of the effect differs between Be2+ and Mg2+ and it varies with the content of cation. This effect has been attributed to the inhibition of the polymerization of monomeric Mo(VI) species and/or to the formation of molybdate salts.
The Shape of Se‐Precipitates in a CdSxSe1−x‐Doped Glass
Authors: Gorski Nikolai , Kalus Jürgen , Kunze Bernd , Bischof Thomas , Kiefer Wolfgang , Wiedenmann Albrecht
Published: March 2014

Small angle neutron scattering (SANS) experiments have been carried out on a semiconductor‐doped glass in order to determine the average size and shape of CdSxSe1−x precipitates (x ≈ 0.7). The crystallites are of spherical shape with a mean radius of Rp = 3.5 ± 0.1 nm and are rather monodisperse. The polydispersity is lower than ΔR/Rp ∼0.1. Approximately 69% of CdSxSe1−x are bound in the precipitates, the rest is dissolved in the glass matrix.
The Effect of Ion Size on Solution Mechanism and Defect Cluster Geometry
Authors: Grimes Robin W. , Busker Gerdjan , McCoy Michael A. , Chroneos Alexander , Kilner John A. , Chen Shao‐Ping
Published: March 2014

Atomistic simulation calculations are used to predict the solution mechanisms and the defect cluster geometries of: M2+ dopant cations in Y2O3, M3+ dopant cations in CoO and M2+ dopant cations in SrTiO3. The interatomic potential parameters were derived by simultaneously fitting the properties of a range of mixed cation materials. The results suggest that although both solution enthalpies and cluster binding energies do scale with ionic radius, the relationships can be quite complex, materials specific and will not necessarily exhibit simple minima when the radius of the host cation equals the dopant cation, as described in previous studies.
First Principles Description of the Valence States in Manganese Oxides
Authors: Mackrodt W. C. , Williamson E.‐A.
Published: March 2014

First principles periodic Hartree‐Fock calculations of Li:MnO, LixMnO2 and CaMnO3 are reported from which direct evidence is presented to indicate that the valence state of Mn remains essentially d5 throughout the series. The net spin moment on Mn, on the other hand, follows that convential change from ∼5μB to ∼3μB associated with the valence states Mn(II), Mn(III), Mn(IV).
Recent Studies of Localized Modes in Crystals
Authors: Sangster M.J.L.
Published: March 2014

Some recent simulations of localized vibrational modes associated with substitutional impurities in crystals are discussed. Most of the examples are for impurities in III–V semiconductors and alkali halides, cases for which improvements in measurement and sample preparation techniques have generated new exacting tests for theoretical models. The displacements of atoms in the modes are revealed by the fine structure from isotopes of both the impurity and the host crystal atoms. Available schemes for modelling these dynamical properties of defects are reviewed.
Migration of Atomic and Molecular Hydrogen in SiO2: A Molecular Dynamics Study
Authors: Bongiorno A. , Colombo L.
Published: March 2014

We present a theoretical investigation on diffusion of atomic and molecular hydrogen in crystalline as well as amorphous silicon dioxide by means of molecular dynamics simulations. We report a characterization of the migration process of atomic hydrogen in quartz and tridymite and we provide an atomistic description of the diffusion of both atomic and molecular hydrogen in silica.
Spectroscopic Studies of High‐Temperature Processes in Oxides
Authors: Becker K.D.
Published: March 2014

Spectroscopic studies can provide important information on physico‐chemical processes in solids, like, e.g., order‐disorder processes, the point defect structure and local defect arrangements, and heterogeneous as well as homogeneous chemical reactions of solids. Results will be reported relating to these topics from experiments that have been performed under in situ conditions, i.e. at high temperatures and under defined conditions of oxygen partial pressures. The examples have been chosen from high‐temperature studies using optical spectroscopy and Mössbauer spectroscopy.
FTIR Spectroscopy to Monitor OH‐Impurity Interactions in Insulating Crystals
Authors: Capelletti Rosanna , Beneventi Paola , Ruffini Andrea
Published: March 2014

Hydroxyl ion is a common impurity in insulating crystals: by interacting with other impurities, it gives rise to new complexes. The OH‐stretching frequency is a very sensitive probe of the hydroxyl environment. High resolution (0.04 cm_1) FTIR spectroscopy in the temperature range 9–300 K was applied to study the OH‐cation impurity interaction in alkali halides, fluoroperovskites, and sillenites, suitable for optoelectronic applications. Proper thermal treatments and isotopic substitutions allowed to assign the stretching mode absorption lines to the defects in which OH– is embedded and to supply possible models for them. Anharmonicity effect of the OH– ‐stretching modes, monitored by weak overtone lines, were well described in the framework of the Morse model. Electric anharmonicity was also detected. The phonon coupling of the OH–‐stretching mode in different defects was studied by analysing the temperature dependence of the line‐position and ‐width: in most cases the single‐phonon coupling model accounted for the experimental data and supplied the coupled phonon frequencies.
Pairing between Radioactive Solutes and Point‐Defects in Semiconductors
Authors: Wichert Thomas
Published: March 2014

The study of solute point‐defect interactions in crystals is performed on an atomic scale by employing radioactive solutes as local observers. Thereby, the presence of a point‐defect next to the solute atom becomes observable via the altered electronic charge distribution about the solute, giving rise to a defect‐specific electric field gradient. Using the perturbed γγ angular correlation technique, this electric field gradient is detected via the hyperfine interaction occurring at the site of the nucleus of the radioactive atom. The sensitivity to solute point‐defect pairs is typically in the order of 1016cm–3. Several properties of these pairs, such as their chemical nature and thermodynamical behaviour are discussed. The point‐defects addressed in this paper are intrinsic, such as lattice vacancies, and extrinsic, such as substitutional and interstitial impurity atoms. Results for the elemental semiconductor Si and different II‐VI compound semiconductors will be discussed.
FTIR Spectroscopy to Monitor Impurities and Impurity‐Interactions in Sillenite Crystals
Authors: Capelletti Rosanna , Beneventi Paola , Kovács László , Ruffini Andrea
Published: March 2014

High resolution (0.04 cm–1) absorption spectroscopy is applied at 9 K to study the role played on the vibrational spectra by impurities (Im), as Si4+, Ge4+, P5+, V5+, Mn5+, and S6+, in Bi12SiO20 (BSO), Bi12GeO20 (BGO), and Bi12TiO20 (BTO) sillenite single crystals. Up to three‐phonon transitions (overtones of the F mode and combination of F and A modes) are detected for the impurities in ImO4 tetrahedra. Weak anharmonicity effects are monitored. The presence of additional Im impurities modify the lines due to a) the stretching of OH, typical of the undoped material, and b) the multi‐phonon transitions either of the intrinsic MeO4 (Me = Si, Ge, and Ti) and of the ImO4 tetrahedra. New bands are monitored due to the Im‐OH interaction.
Models of Matter Transport: Their Verification and Use for Dilute Systems with the Aid of Statistical Theories
Authors: Allnatt A.R.
Published: March 2014

Statistical expressions for the Onsager phenomenological coefficients are now available for several models of matter transport in systems which are dilute in solutes, vacancies and interstitials. They describe transport by unpaired and paired defects, as in the familiar five‐frequency model. The role of atomistic calculations of the parameters of such models in validating, simplifying or improving them is illustrated. In general it may be difficult to convincingly determine from experiment all the parameters of a given model or to distinguish between closely related models, such as between those retaining first or first and second neighbour binding between a solute and a vacancy. Nevertheless, there is particular utility in knowledge of all the Onsager coefficients for models suggested by atomistic calculations and other information, when one interprets phenomena involving coupled fluxes. This is illustrated by the example of coupled fluxes of a solute, vacancies and interstitials in a dilute alloy under steady irradiation by high energy particles. Here, essential contributions to modelling solute segregation to grain boundaries can be made; striking qualitative differences between closely related models can occur in this case. Finally, the limitations of the current statistical results are examined for systems where the solutes and defects carry effective charges. Limitations are suggested at low temperatures by the existence of a phase transition in the restricted primitive model of dilute aqueous electrolytes. The range of concentration and temperature within which the current procedures, stemming from the early work of Teltow and Lidiard, have been properly validated is limited. In the absence of recent theoretical advances Monte Carlo simulation is becoming the method of choice in investigating such limitations and in studying the transition to higher concentrations where there are larger clusters of defects.
Proton Dynamics in Interacting Hydrogen Bonds in the Solid State: Proton Tunneling in the NHO Hydrogen Bonds of N,N′‐Di(2‐Hydroxy‐1‐Naphthylmethylene)‐p‐Phenylenediamine
Authors: Takeda Sadamu , Inabe Tamotsu , Benedict Claudia , Langer Uwe , Limbach Hans‐Heinrich
Published: March 2014

Combination of comprehensive investigations of the spin‐lattice relaxation rate of proton and low temperature 15N‐CP/MAS NMR spectrum provides unique information of proton dynamics in two interacting NHO hydrogen bonds of solid N,N′‐di(2‐hydroxy‐1‐naphthylmethylene)‐p‐phenylenediamine (DNP). It was evidenced from the 1H‐NMR relaxation measurement that tunneling mechanism operates for the proton transfer in the hydrogen bonds. The tunneling phenomenon is closely related to the very small energy differences among the four tautomeric states accompanied with the proton transfer in the two NHO hydrogen bonds. The very small values of the energy difference, in spite of the chemically asymmetric NHO hydrogen bond, were revealed by the 15N‐CP/MAS NMR spectrum. This is a unique character of solid DNP. It was also suggested from the derived energy scheme of the four tautomers and activation energies of the proton transfer that an interaction exists between the two NHO hydrogen bonds linked by π‐electronic molecular frame. This means that the information of one NHO hydrogen bond, i.e. OH‐form or NH‐form, propagates to the other hydrogen bond and the proton transfer in the first hydrogen bond induces the change of the potential function for the proton transfer in the second hydrogen bond.
Electrochemistry of Steel Electrodes: A Combined Study by Linear Reflectivity Measurements and Second Harmonic Generation
Authors: Kohring R. , Buck M. , Eisert F. , Grunze M. , Vogelsang J.
Published: March 2014

Steel electrodes were investigated under electrochemically controlled conditions at pH 13. The linear reflectivity at 1064 nm and the second harmonic signal (SHG) at 532 nm generated in reflection were measured for different polarizations and recorded simultaneously with cyclovoltammograms. The potential was varied between −1.4 V and 0.5 V vs. SCE and the optical signals were recorded after repetitive cycling. The reflectivity which probes the whole thickness of the electrochemically active layer and the non‐linear optical signal which, in contrast, only probes the electrode surface and its immediately vicinity, exhibit very different behavior with respect to their potential dependence. In a cathodic scan the increase of the respective optical signals is associated with different peaks of the cyclovoltammogram. Furthermore, the SHG signal is strongly dependent on the polarization. The pronounced changes around −1.25/‐1.1 V in the cathodic/anodic scan direction, which are observed for pp‐polarization, are absent in sp‐ and ms‐polarization. The sp‐signal shows features which are paralleled by a decrease in the linear reflectivity. Contrary to the other polarizations, the ms‐polarized signal does not show any particular features correlated with peaks of the cyclovoltammogram. The potential dependence of the surface charge expressed by a simple parabolic model describes the SHG signal over extended parts of the potential range. The differences between the potential dependence of the SHG signal and the change of the linear reflectivity fully agree with the two layer model of electrochemically formed iron oxides.
Thermodynamics of Vanadium Redox Flow Batteries ‐ Electrochemical and Calorimetric Investigations
Authors: Heintz A. , Illenberger Ch.
Published: March 2014

Thermodynamic properties of the so‐called All‐Vanadium battery used as energy storage system and other vanadium redox systems related to the All‐Vanadium battery have been studied. An electrochemical cell has been constructed to measure the equilibrium cell voltages as function of the degree of charging in the temperature range from 278 K to 323 K. The first system studied is the disproportion reaction of VO2+ ions with the two half cell reactions VO2+ + H2O ⇄ VO+2 + 2H+ + e− and VO2+ + 2H+ + e− ⇄ V3+ + H2O. The second system is the All‐Vanadium battery reaction with the two half cell reactions VO2+ + H2O ⇄ VO+2 + 2H+ + e− and V3+ + e− ⇄ V2+. The third system is the disproportion reaction of V3+ ions with the half cell reactions V3+ + H2O ⇄ VO2+ + 2H+ + e− and V3+ + e− ⇄ V2+. The molar reaction Gibbs energy, the molar reaction enthalpy, and the molar reaction entropy of each system has been obtained from these data. Additionally the molar reaction enthalpy of the two disproportion reactions and of the reaction V2+ + 2VO2+ + 2H+ → 3VO2+ + H2O has been measured directly by titration calorimetry. The results agree with those obtained from the electrochemical data for the disproportion reactions. No direct calorimetric measurements of the molar reaction enthalpy of the All‐Vanadium battery reaction is possible, but the sum of the molar reaction enthalpies of the two disproportion reactions gives the molar reaction enthalpy of the All‐Vanadium battery reaction. Comparison with the electrochemically determined molar reaction enthalpy of the All‐Vanadium battery reaction shows good agreement indicating satisfying thermodynamic consistency of the whole procedure.
Polymer‐Surfactant Interactions: Non Ionic Polymers with SDS and DTABr
Authors: La Mesa Camillo , Persi Livio , D'Aprano Alessandro
Published: March 2014

Polymer‐surfactant interactions in water‐SDS‐polyvinylpyrrolidone (PVP), water‐SDS‐polyoxyethylenglycol (PEO), water‐(DTABr)‐(PEO) and in water‐SDS‐polyoxypropylenglycol (PPO), systems have been investigated by ultrasonic relaxation, adiabatic compressibility and viscosity measurements.

Both the hydrodynamic and thermodynamic properties show significant changes at the critical association concentration in presence of polymer. As to the kinetic behaviour, investigation on systems containing PEO or PVP indicates the occurrence of a region where relaxation times are nearly constant. For the low molecular weight PPO polymer this effect has not been observed. Such differences have been ascribed to the minimum polymer chain length effect, required for the binding of surfactant aggregates on the polymer backbone. The dynamics of polymer‐surfactant interactions has been discussed in terms of a kinetic model, previously proposed.
Determination of the ortho‐, para‐, and meta‐Interactions in secondary‐Alkylphenols from Thermochemical Measurements
Authors: Verevkin Sergey P.
Published: March 2014

The standard molar enthalpies of formation ΔfH0m, (1 or cr) at the temperature 298.15 K were measured by using combustion calorimetry for 4‐ethylphenol, 2‐iso‐propylphenol, 2‐iso‐propyl‐5‐methylphenol, 2‐sec‐butyl‐phenol, 4‐iso‐propylphenol, 4‐sec‐butylpnenol, and 4‐cyclo‐hexylphenol. The enthalpy of formation ΔfH0m, (1) of 3‐iso‐propylphenol was obtained from the results of calorimetric and equilibrium studies. The standard molar enthalpies of sublimation (or vaporization) of these compounds, and also of phenol, were obtained from the temperature dependence of the vapour pressure measured in a flow system. Molar enthalpies of fusion Δ1crH0m of the solid compounds were measured by d.s.c. Resulting values of ΔfH0m (g) were obtained at the temperature 298.15 K and used to derive strain enthalpies of alkylphenols. The intra‐molecular interactions of the substituents were discussed in terms of deviations of ΔfH0m (g) from the group additivity rules. Ortho‐, para‐, and meta‐interactions of sec‐alkyl substituent with OH‐group in the gaseous phase was found to be equal 3.9 kJ·mol−1. These values provided a further improvement on the group‐contribution methodology for estimation of thermodynamic properties of organic compounds.
Kinetics of the Gas‐Phase Reaction of NO3 Radicals with 1‐Butene, trans‐Butene, 2‐Methyl‐2‐butene and 2,3‐Dimethyl‐2‐butene Using LIF Detection
Authors: Berndt T. , Kind I. , Karbach H.‐J.
Published: March 2014

Rate constants for the gas‐phase reaction of NO3 radicals with 1‐butene, trans‐butene, 2‐methyl‐2‐butene and 2,3‐dimethyl‐2‐butene have been obtained in a flow system at 298±2 K and a pressure of 3 mbar He using NO3 LIF measurements. NO3 radicals were produced via thermal decomposition of N2O5 at ca. 400 K, i.e. N2O5+M → NO3+NO2+M.

Applying pseudo‐first‐order conditions, the rate constants for 1‐butene and trans‐butene were found to be (1.04±0.11)·10−14 and (3.74±0.45)·10−13, respectively. For 2‐methyl‐2‐butene and 2,3‐dimethyl‐2‐butene the rate constants were obtained under second‐order conditions to be (1.03±0.09)·10−11 and (5.49±0.42)·10−11, respectively (unit: cm3 molecule−1 s1).
Contributions to the Spectroscopic‐Kinetic Analysis of Linear Reaction Systems: Systems with Two Linearly Independent Reactions Using the Concept of Parallel Projection
Authors: Polster J.
Published: March 2014

Multistep protolysis or metal‐complex systems can be divided into their individual titration equilibria by the concept of projective mapping using diagrams which contain only absorbance data. In this way, the individual equilibria constants and their ratios can be very easily determined. The concept can be transfered to the spectroscopic‐kinetic analysis of linear reaction systems. Reaction systems which are described by two linearly independent concentration variables (s = 2) can be reduced to systems which depend only on one linearly independent concentration variable (s = 1) by replacing the perspective projection by a parallel projection. The new method is demonstrated by application to the spontaneous hydrolysis of Boc‐gly‐ONP (N‐tert.‐Butoxycarbonyl glycine p‐nitrophenylester) and oNPA (o‐nitrophenyl acetate) in borax buffer (pH = 8.7).
Kinetic Studies on Reversible Dimerization of Thianthrene and 2,3,7,8‐Tetramethoxythianthrene Radical Cations
Authors: Hübler Patrick , Heinze Jürgen
Published: March 2014

Fast scan voltammetry gives kinetic evidence for the reversible dimerization of the radical cations of thianthrene (T) and 2,3,7,8‐tetra‐methoxythianthrene (TMOT) in acetonitrile. At 256 K an equilibrium constant KDim ≈ 900 for TMOT (KDim ≈ 1.1·104 for T) and rate constants kf ≈ 1·107 and kb ≈ 1.2·104 were determined. Using the semi‐empirical PM3 method, the formation of σ‐bonded dimers is indicated. For the dimerization reaction in acetonitrile, enthalpy values of −79 kJ/mol for T and −56 kJ/mol for TMOT respectively were calculated. Despite the folded structure of the neutral T and TMOT systems and their planarization during the radical cation formation, the heterogeneous electron transfer kinetics was found to be very fast in both cases (1.6 cm/s; 298 K). The activation enthalpy was determined to be 14 kJ/mol in the case of TMOT. Calculations of the inner‐sphere reorganization energy using the Marcus theory produced ΔH#(∞) = 4.6 kJ/mol for TMOT and 3.9 kJ/mol for T respectively at infinite temperatures. This explains the fast electron transfer kinetics and their low activation enthalpies.
Beyond inhibition: GABA synapses tune the neuroendocrine stress axis
Authors: Inoue Wataru , Bains Jaideep S.
Published: March 2014

We recently described a novel form of stress‐associated bidirectional plasticity at GABA synapses onto hypothalamic parvocellular neuroendocrine cells (PNCs), the apex of the hypothalamus‐pituitary‐adrenal axis. This plasticity may contribute to neuroendocrine adaptation. However, this GABA synapse plasticity likely does not translate into a simple more and less of inhibition because the ionic driving force for Cl−, the primary charge carrier for GABAA receptors, is dynamic. Specifically, stress impairs a Cl− extrusion mechanism in PNCs. This not only renders the steady‐state GABA response less hyperpolarizing but also makes PNCs susceptible to the activity‐dependent accumulation of Cl−. Accordingly, GABA synapse plasticity impacts both the robustness of GABA voltage response and dynamic Cl− loading, imposing nonlinear influences on PNC excitability during circuit activities. This theoretical consideration predicts roles for GABA transmission far more versatile than canonical inhibition. We propose potential impacts of GABA synapse plasticity on the experience‐dependent fine‐tuning of neuroendocrine stress responses.
Clinical effectiveness of posaconazole versus fluconazole as antifungal prophylaxis in hematology–oncology patients: a retrospective cohort study
Authors: Kung Hsiang‐Chi , Johnson Melissa D. , Drew Richard H. , Saha‐Chaudhuri Paramita , Perfect John R.
Published: March 2014

In preventing invasive fungal disease (IFD) in patients with acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS), clinical trials demonstrated efficacy of posaconazole over fluconazole and itraconazole. However, effectiveness of posaconazole has not been investigated in the United States in real‐world setting outside the environment of controlled clinical trial. We performed a single‐center, retrospective cohort study of 130 evaluable patients ≥18 years of age admitted to Duke University Hospital between 2004 and 2010 who received either posaconazole or fluconazole as prophylaxis during first induction or first reinduction chemotherapy for AML or MDS. The primary endpoint was possible, probable, or definite breakthrough IFD. Baseline characteristics were well balanced between groups, except that posaconazole recipients received reinduction chemotherapy and cytarabine more frequently. IFD occurred in 17/65 (27.0%) in the fluconazole group and in 6/65 (9.2%) in the posaconazole group (P = 0.012). Definite/probable IFDs occurred in 7 (10.8%) and 0 patients (0%), respectively (P = 0.0013). In multivariate analysis, fluconazole prophylaxis and duration of neutropenia were predictors of IFD. Mortality was similar between groups. This study demonstrates superior effectiveness of posaconazole over fluconazole as prophylaxis of IFD in AML and MDS patients. Such superiority did not translate to reductions in 100‐day all‐cause mortality.
Blended Learning – An Innovative Concept for Advanced Vocational Training in Chemical Technology
Authors: Jäger Kathrin , Moros Ralf , Geißler Anja , Gläser Roger
Published: March 2014

Die ständig wachsenden und wechselnden Anforderungen des Arbeitsmarktes setzen die Bereitschaft von Fach‐ und Führungskräften zu einer stetigen und berufsbegleitenden Weiterbildung voraus. Zudem existiert von Seiten der Fachkräfte der Wunsch nach Vereinbarkeit von Beruf und Familie. Vor diesem Hintergrund wurde ein auf der Grundlage des Blended Learning beruhendes Konzept für naturwissenschaftlich‐technische Weiterbildungsangebote erarbeitet. Exemplarisch wurde dieses Konzept für das Gebiet der Technischen Chemie anhand des Weiterbildungskurses „tc‐compactBL”︁ umgesetzt und erprobt.
Low‐temperature catalytic activity of CO oxidation by uni‐size Pt30 cluster disks bonded to silicon substrate
Authors: Yasumatsu Hisato , Fukui Nobuyuki
Published: March 2014

We investigated catalytic activity of CO oxidation by monatomic‐layered cluster disks, Pt30, bonded to a silicon substrate by means of ultrahigh‐sensitive temperature‐programmed desorption (TPD) mass‐spectrometry. It was found in the repeated TPD measurements with various reactant‐exposure amounts that this cluster‐substrate system possesses high ability of low‐temperature reductive activation of oxygen molecules, which is the rate‐determining step of the CO oxidation. This high‐performance is explained in terms of negative charges accumulated at a subnano interface between the cluster disk and the silicon substrate surface.
Tribological contact stability of hard and soft cleaning projectiles
Authors: Malayeri M. Reza , Jalalirad Mohammad R.
Published: March 2014

Tribological properties of projectiles, i.e. contact stability with the tube through which they pass, are of prime importance for the selection of soft or hard projectiles for on‐line cleaning of tubular exchangers. To do so, this study proposes two methods of firstly measuring pressure in the back of projectiles under the force of flow and secondly the shear by mechanical force using a tensometer. The experimental results show that hard projectiles exert a much higher mechanical shear on the surface, nevertheless much lower hydrodynamic shear under the propulsion of flow. This is mainly due to reduced and unstable contact area between the projectile and tube surface. Accordingly a new term “contact stability or Z factor” is proposed which has a strong relation to the stiffness of projectiles. The Z factor is low for hard projectiles and vice versa. A set of fouling runs, under similar operating conditions, is also conducted for hard and soft projectiles as well as when no projectile is shot. While a hard projectile can exert a shear of 12‐fold larger than a soft projectile, its cleanability is not appreciably better. The reason was attributed to poor contact stability with the tube surface.
Local treatment of high risk prostate cancer: Role of surgery and radiation therapy
Authors: Borza Tudor , Kibel Adam S.
Published: March 2014

The current management of patients with high‐risk prostate cancer is hampered by overstaging. This editorial reviews the referenced article as well as outlines the treatment strategies for patients with aggressive disease.
The impact of pathologic staging on the long‐term oncologic outcomes of patients with clinically high‐risk prostate cancer
Authors: Abern Michael R. , Terris Martha K. , Aronson William J. , Kane Christopher J. , Amling Christopher L. , Cooperberg Matthew R. , Freedland Stephen J.
Published: March 2014

BACKGROUND

In the prostate‐specific antigen (PSA) screening era, approximately 15% of US men still present with clinically high‐risk prostate cancer (PC). However, high‐risk PC may be downgraded/downstaged at radical prostatectomy (RP), making additional therapy unnecessary. The authors tested the oncologic outcomes in men with clinically high‐risk disease stratified on RP pathology.

METHODS

A total of 611 men with high‐risk PC (PSA level > 20 ng/mL, biopsy Gleason sum [bGS] ≥ 8, or clinical classification of ≥ T3) underwent RP and pelvic lymphadenectomy between 1998 and 2011. Outcomes included biochemical disease recurrence (BCR), receipt of androgen deprivation therapy (ADT), metastases, and PC‐specific and overall survival. RP pathology was classified as unfavorable (pathologic Gleason sum ≥ 8, pathologic classification of ≥ T3, or lymph node‐positive disease), or favorable (no unfavorable features). Multivariable analyses tested oncologic outcomes stratified by pathologic classification.

RESULTS

Overall, 527 men had complete pathologic data and were included in the current analysis. Of the cohort, 206 of 527 men (39%) had favorable pathology. This finding was more common in men with only 1 clinical high‐risk feature, and a lower body mass index, PSA level, bGS, and percentage positive biopsy cores. Favorable pathology was associated with decreased BCR (hazards ratio [HR], 0.34), metastases (HR, 0.17), and PC death (HR, 0.17). After a median follow‐up of 82 months (range, 49 months‐131 months), 193 of the 527 men (37%) received ADT, including only 35 of the 206 men with favorable pathology (17%). Unfavorable pathology was associated with early (≤ 5 years) but not late treatment with ADT.

CONCLUSIONS

In a large cohort of men with high‐risk PC who were managed with RP, 39% had favorable pathology and superior oncologic outcomes. Cancer 2014;120:1656–1662. © 2014 American Cancer Society.
Shared decision‐making and patient control in radiation oncology: Implications for patient satisfaction
Authors: Shabason Jacob E. , Mao Jun J. , Frankel Eitan S. , Vapiwala Neha
Published: March 2014

BACKGROUND

Shared decision‐making (SDM) has been linked to important health care quality outcomes. However, to the authors' knowledge, the value of SDM has not been thoroughly evaluated in the field of radiation oncology. The objective of the current study was to determine the association between SDM and patient satisfaction during radiotherapy (RT). The authors also explored patient desire for and perception of control during RT, and how these factors relate to patient satisfaction, anxiety, depression, and fatigue.

METHODS

A cross‐sectional survey of 305 patients undergoing definitive RT was conducted. Patients self‐reported measured variables during the last week of RT. Relationships between variables were evaluated using chi‐square analyses.

RESULTS

Among study participants, 31.3% of patients experienced SDM, 32.3% perceived control in treatment decisions, and 76.2% reported feeling very satisfied with their care. Patient satisfaction was associated with perceived SDM (84.4% vs 71.4%; P < .02) and patient‐perceived control (89.7% vs 69.2%; P < .001). Furthermore, the perception of having control in treatment decisions was associated with increased satisfaction regardless of whether the patient desired control. Increased anxiety (44.0% vs 20.0%; P < .02), depression (44.0% vs 15.0%; P < .01), and fatigue (68.0% vs 32.9%; P < .01) were reported in patients who desired but did not perceive control over their treatments, compared with those who both desired and perceived control.

CONCLUSIONS

The findings of the current study emphasize the value of SDM and patient‐perceived control during RT, particularly as it relates to patient satisfaction and psychological distress. Regardless of a patient's desire for control, it is important to engage patients in the decision‐making process. Cancer 2014;120:1863–1870. © 2014 American Cancer Society.
Modeling diffusion of energy innovations on a heterogeneous social network and approaches to integration of real‐world data
Authors: Bale Catherine S. E. , McCullen Nicholas J. , Foxon Timothy J. , Rucklidge Alastair M. , Gale William F.
Published: March 2014

A model has been developed to simulate the diffusion of energy innovations on a heterogeneous social network. Nodes on a network represent households, whose adoption of an energy innovation is based on a combination of personal and social benefit; social benefit includes the positive influence from an individual's personal social network and feedback from the wider population. This article describes the development of the model to incorporate heterogeneous parameters and, thus, become more like a real social system. The sensitivity of the model is investigated and it is shown that heterogeneity matters. This has important implications for the inclusion of real‐world data into this type of model. © 2014 Wiley Periodicals, Inc. Complexity 19: 83–94, 2014