bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical solid state spectroscopy by holographic grating techniques with quantum limited sensitivity
Authors: Bráuchle Chr.
Published: March 2014

In the past holographic gratings have been used successfully with cw and pulsed laser sources to study a broad variety of photophysical and photochemical phenomena of molecules in solid, liquid and gas phase. In this paper a newly developed holographic grating technique, called phasemodulated holography (PMH), is presented. With this technique for the first time a separated and simultaneous monitoring of the amplitude and phase gratings including the absolute signs of these contributions is possible. Thus hologram formation mechanisms and the underlying photochemistry can be studied in great detail. This feature and an up to eight orders of magnitude improvement of detection sensitivity over conventional techniques makes PMH an ideal tool for the investigation of new materials for holographic optical information storage. This will be demonstrated for several examples i. e. photoactive molecules incorporated in polymer systems.
Photophysical hole burning on dye solutions in the liquid phase with ns‐laserpuises
Authors: Menzel Ralf , Witte Peter
Published: March 2014

The necessary conditions for observing inhomogeneous bleaching of the electronic absorption bands of organic molecules in solution at room temperature have been investigated by simple rate equation models. For systems with ground state recovery times in the ps‐range, photophysical hole burning (PPHB) can be obtained with the ns‐laserpulses. The measured experimental result for crystal violet in acetonitrile may serve as an example. In transitions between excited states PPHB is possible as an universal method on probably all organic molecules. This has been demonstrated for the S1‐absorption band of para‐terphenyl at 570 nm. The given brief outline of methods, results, and conclusions will be described separately in more detail.
Diffusion of excess electrons in decomposing liquid metal‐ammonia solutions in the high‐conducting state, injected into a zero‐electric field space
Authors: Arendt P.
Published: March 2014

The diffusive motion of electrons in the high‐conducting state of decomposing liquid lithium‐ammonia and sodium‐ammonium solutions in response to a non‐uniform concentration of electrons has been investigated. Excess electrons are produced near a permeable anode and through it injected into a zero‐external electric field space behind the anode. The excess electrons diffuse away from the anode over an average distance of about 1.5 cm during their lifetime in the high‐conducting state, which indicates through the Nernst‐Einstein relation a very large electric mobility of the electrons.
New strategies for studies on the kinetics and energetics of the Belousov‐Zhabotinskii reaction
Authors: Koch E. , Nagy‐Ungvarai Zs.
Published: March 2014

The oscillatory Belousov‐Zhabotinskii reaction and its subsystems were studied by ≈ 1700 DTA and UV experiments performed at linearly increased temperature. The starting concentrations of bromate, bromide, catalyst, and malonic acid were varied in order to obtain “concentration codes” of such series. These represent the dependence of any parameters in discrete ranges of the starting concentrations of the different components. Particularly adequate for a model check are the mechanistic codes (=MCC's), which concern the shape index and reaction type index: If these mechanistic coordinates remain constant in such a concentration interval, other data, e.g. activation energies, can be attributed to a rate‐determining process. — The results led to a nine‐step model which is based on the FKN mechanism and is capable of roughly reproducing the influence of the initial concentrations and heating rate on 11 parameters characteristic of the envelope and of the oscillations of the experimental signals. The MCC's of the experimental and theoretical series are similar, revealing 4 — 5 rate‐determining steps in the different concentration ranges.— The activation energies agree with values from the literature, cited for three steps; these and further resulting activation energies are consistent with our studies with subsystems.
Thermodynamic analysis of partition data in the CaCl2‐H2O‐n‐Octanol and CaCl2‐H2O‐n‐butanol systems at 298.15 K
Authors: Apelblat Alexander , Manzurola Emanuel
Published: March 2014

Simultaneous extraction of calcium chloride and water by n‐octanol and n‐butanol is described. In the system with n‐octanol, the experimental results are consistent with formation of partly dissociated CaCl2(H2O)5(ROH)5 complex in the organic phase. The equilibrium constant for complex formation is K = 6.3 · 10−7 mol−1 kg. In the case of n‐butanol, only at low concentrations of calcium chloride, the extraction can be represented by formation of CaCl2(H2O)7(ROH)8, complex with K = 0.056 mol−1 kg. Activities of alcohols in the organic phase were evaluated by a numerical integration of the Gibbs‐Duhem equation. The solubility of water in n‐butanol as a function of water activity was also determined.
A New Statistical Model for Adsorption of Mixtures on Heterogeneous Surfaces
Authors: Liedy W. , Schlünder E.‐U.
Published: March 2014

A new model for adsorption equilibria on heterogeneous surfaces is developed. First an analytical equation for single‐component adsorption is derived. Then the model is extended to mixtures. The comparison with experimental data shows that single‐component data can be described and extrapolated in a wide pressure and temperature range. The mixture data of a strongly real adsorpt system can be predicted with good accuracy only from single‐component sorptive data and the vapor‐liquid equilibrium of the considered system. A simplified model with mixture parameters gives good extrapolation to other temperatures.
Counterion Accumulation in Rod‐Like Polyelectrolyte Solutions with Added Salt and Manning's Condensation Theory
Authors: Bizzarri A. R. , Cametti G. , Di Biasio A.
Published: March 2014

The Poisson‐Boltzmann equation in the cylindrical cell model is solved numerically for charged polyelectrolyte solutions containing mono‐ or di‐valent counterions and mono‐valent coions. The results, which describe the ion distribution around the polyion, are compared with those derived from the Poisson‐Boltzmann equation for salt‐free solutions in the limit of infinite dilution and with the Manning counterion condensation theory. This approach generalizes the results of Le Bret and Zimm for the dependence of the condensation radius on the polyion concentration to polyelectrolyte solutions containing added salt and shows how counterion condensation occurs even at finite concentration. The general conclusion drawn not only supports further evidences that the Manning condensation theory can be deduced from the Poisson‐Boltzmann equation but also suggests that counterion binding changes progressively from a free to condensed phase, as the polyion charge density parameter increases.
The Kinetics of the Interfacial Diffusion Controlled Electrochemical Processes at Non Porous Electrode/Solid Electrolyte Interfaces of Finite Dimensions
Authors: Barbi G. B. , Beonio‐Brocchieri F.
Published: March 2014

The functional dependence of current density and overpotential for an electrochemical process taking place at the interface between a “blocking” electrode and a solid electrolyte and whose rate determining step is the tangential diffusion over the interface was evaluated. — The conditions of applicability to such systems of the classical electrochemical kinetics were criticized. — In particular, it was put into evidence that, even in the case of a linear trend between the logarithm of the current density and overpotential, the extrapolation of the straight line portion to zero overpotential in some cases does not allow the determination of the value of the exchange current density.
Intracluster Proton‐Transfer between Methylsubstituted Benzene Cations and Polar Solvent Molecules Studied by Resonant Two‐Photon Ionization
Authors: Brutschy B. , Janes C. , Eggert J.
Published: March 2014

Intracluster proton‐transfer was observed for mixed clusters of toluene and p‐xylene with polar solvent molecules (NH3, CH3OH, D2O) after resonant two‐photon ionization of the aromatic moiety. The transfer is deduced from the appearance of protonated solvent clusters, showing the R2PI spectra of their mixed cluster precursors. This process, observable only in combination with subsequent dissociation, is cluster size dependent. The minimum number of solvent molecules necessary for a transfer to take place depends on the solvent's proton solvation energy.
A Gasphase Kinetic Investigation of the System F + HNO3 and the Determination of Absolute Rate Constants for the Reaction of the NO3 Radical with CH3SH, 2‐Methylpropene, 1,3‐Butadiene and 2,3‐Dimethyl‐2‐Butene
Authors: Rahman M. M. , Becker E. , Benter Th. , Schindler R. N.
Published: March 2014

The reaction of HNO3 with atomic fluorine (1) has been studied in a discharge‐flow system at 298 K. Mass spectrometric detection with single ion counting was employed. The rate constant for the primary reaction (1) at 298 K. has been determined from the rate of HF and NO, formation under conditions [HNO3] ≫ [F]0 and the rate of HNO3‐removal under conditions [F] ≫ [HNO3]0

From the patterns of growth and decay of the primary product NO3 and the secondary product FO under various ratios of the initial concentrations of the reactants, the rate constants of the following secondary reactions have been determined:

Further, the rate constants for the reactions of NO3 with CH3SH, 2‐methylpropene, 1,3‐butadiene and 2,3‐dimethyl‐2‐butene at 298 K have been determined by introducing these reactants into the flow system and measuring their consumption under pseudo‐first‐order conditions. The values of the rate constants obtained are 7.7 ± 0.5, 3.3 ± 0.5, 1.7 ± 0.3 and 384 ± 38 in units of 10−13 cm5 s−1 respectively. A comparison is made between the values determined in this work and those reported in the literature.
Ion Relaxation in Aqueous Polyethyleneoxide Solutions Studied by Nuclear Magnetic Relaxation
Authors: Breen J. , Huis L. , De Bleijser J , Leyte J. C.
Published: March 2014

The nuclear magnetic relaxation rates of some ions are studied in aqueous PEO solutions. The relative molal increase of the ion relaxation is obtained for a number of ions. In a limited range the DP‐dependence, salt concentration dependence and temperature dependence are investigated. The quadrupolar relaxation mechanism of ions provides a means to investigate the ion hydration complex. The enhancement of the ion relaxation rate by the presence of PEO is interpreted by an ion hydrationcomplex‐PEO interaction. Two dynamical models are evaluated. One of the models is able to explain the NMR results and does not contradict the results obtained from neutron diffraction experiments.
Photoionization and Photodissociation of Allene Clusters in a Supersonic Molecular Beam
Authors: Rühl E. , Brutschy B. , Bisling P. , Baumgärtel H.
Published: March 2014

The cluster photoionization mass spectrum of allene (1,2‐propadiene) (C3H4) has been measure with synchrotron radiation from the electron storage ring BESSY. Cluster cations and characteristic fragmentation patterns are observed which are differing depending on the cluster size. The allene dimer decays mainly into C3H5+ and C6H7+. The trimer fragmentation yields mainly C7H7+, C7H8+, and C8H9+. These cations are formed by abstraction of methyl, ethene, and ethyl groups, respectively. The parentage of the fragmentation products has been assigned by measuring the pressure dependence of the ion signals. The energetics of the ionization and fragmentation processes has been studied by means of appearance potential measurements. From these values intermolecular binding energies of the cationic complexes are obtained. The role of stable precursor cations and the evidence of energy barriers are discussed for the dominating cluster fragmentation reactions. The role of proton transfer reactions within allene clusters is discussed in terms of charge distributions obtained from MNDO calculations.
Intramolecular and Fragmentation Dynamics of Van der Waals Complexes
Authors: Wozny Christopher E. , Gray Stephen K.
Published: March 2014

The classical phase space dynamics of a simple two degree of freedom model for the vibrational predissociation (i.e. fragmentation) of van der Waals complexes is reviewed, with emphasis being placed on the role of transitions across intramolecular and intermolecular bottlenecks. A similar phase space picture is proposed to exist in van der Waals systems with three or more degrees of freedom. Evidence for this is presented with a 3D classical trajectory study of NeCl2 fragmentation. An approximate intermolecular bottleneck is explicitly constructed for this system.
Vector Correlations in Molecular Photodissociation: H2O2, HONO2 and (CH3)3COOH
Authors: August Julie , Brouard M. , Docker M. P. , Hodgson A. , Milne C. J. , Simons J. P.
Published: March 2014

Doppler resolved, laser induced fluorescence spectroscopy has been established as a powerful probe for determining scalar energy distributions among primary photofragments. Measurements of the sensitivity to alternative excitation‐detection beam geometries and polarisations and the choice of the monitored rotational features, P↑, R↑ or Q↑ has now made LIF probing even more powerful, by revealing additional information on their momentum distributions. These are expressed in terms of a family of vector correlations: the translational anisotropy, the rotational alignment and the helicity. – New data are presented and analysed for three archetypal systems, H2O2, HONO2, (CH3)3COOH, each of which presents totally featureless U.‐V. absorption continua. Doppler resolved LIF spectroscopy of the recoiling OH fragments generated by laser photodissociation at 248 nm (H2O2, (CH3)3COOH) or 280 nm (HONO2) is used to assign the electronic transitions, the structural changes which follow excitation, and their influence on the intramolecular dynamics involved in the photodissociation process.
Dynamics of Molecular Photofragmentation
Authors: Comes F. J. , Gericke K. H. , Grunewald A. U. , Klee S.
Published: March 2014

Photodissociation dynamics provides a vast amount of information in understanding chemical dynamics. The obtained energy‐release data describe scalar properties of the chemical interaction which can be compared directly with the results of classical or quantum mechanical scattering calculations. However, even a complete knowledge of the product distribution provides only a limited view of the dissociation process, as long as vector correlations between observables are not taken into account. These correlations can be obtained by measuring Doppler profiles of the products using polarized light and different excitation and detection geometries. – The correlation between the transition dipole moment μ in the parent and the recoil velocity v of the fragment, as well as the correlation between μ and the rotational vector J of the product, may reveal the symmetry and geometry of the dissociative state. Any decrease in fragment anisotropy of directional properties caused by parent rotation gives information on the lifetime of the parent excited state. Very recently a substantial progress in the field of photodissociation dynamics has been achieved by observing not only the <μJ> and <μv> correlation but also the correlation between the rotational and translation motion of the fragment, <μJ>, and between μ, v, and J. – Observation of fragment anisotropy can also be used to discriminate between two different dissociation channels. If two electronic states are responsible for the dissociation process, the observed line shape is a linear combination of two Doppler profiles. The bipolar moments of the <μv> correlation for each contributing parent dissociation channel can be used to calculate the product state distribution referring to the two different fragmentation channels. As an example, the dynamics of the photofragmentation of the H2O2 and D2O2 is analyzed by a characterization of scalar and directed properties of the recoiling OH fragments.
Width Distributions for Random Interstate Coupling
Authors: Dietz W.
Published: March 2014

Differential probability distribution functions are calculated for the widths of oscillator carrying (light) states perturbed by statistically independent background states. Simple analytical expressions are given for the most probable value and fluctuation in case of dense or sparse background manifolds. In these limits the rescaled distributions are independent from model parameters. As example the model is applied to the 1410120 vibronic band of benzene. The results are compared with a previous, more specific model.
New Order Out of the Chaotic Bath of Highly Vibrational States of C2H2
Authors: Pique J. P. , Lombardi M. , Chen Y. , Field R. W. , Kinsey J. L.
Published: March 2014

Using a Statistical Fourier Transform (SFT) technique we show the first evidence of a very soft mode (5.5 cm−1) out of the chaotic vibrational spectrum of C2H2 at 26500 cm−1 above the ground state.
Multiphoton Ionization Studies of Energy Transfer in Highly Excited Ground State Molecules
Authors: Luther K. , Reihs K.
Published: March 2014

A multiphoton ionization method, the “kinetically controlled selective ionization” (KCSI), is presented which is suitable for observations of the time evolution of molecular populations at selected vibrational energies even in cases of unresolvable high densities of states. In collisional energy transfer this technique allows the first experimental determination of 〈ΔE2〉, and therefore of a population distribution of highly excited molecules during the relaxation. In addition it provides sensitive detection of 〈ΔE〉, the average amount of energy transferred per collision, and its energy dependence. Examples of such measurements are shown and discussed.
Chemical Exchange and Raman Line Broadening II
Authors: Strehlow H.
Published: March 2014

A simple equation for the line shape of Raman (or infrared) spectra is provided for systems subject to fast chemical exchange with average life‐times between about 3 · 10−13 and 10−11 s. The equation is compared with the corresponding one for NMR line broadening.
A Proton Magnetic Resonance and Gravimetric Study of Water and Isopropanol Adsorption on Microcrystalline Rutile. II. Hydration and Hydroxylation
Authors: Boddenberg B. , Horstmann W.
Published: March 2014

By means of1H magnetic resonance the time domain line shapes of water adsorbed on a microcrystalline titania (rutile) at three different coverages were measured as function of temperature (77 to 350 K) and resonance frequency (21 to 90 MHz). Evidence is obtained that dissociation of chemisorbed water even on the (110) surface planes amounts to not more than about 33%. Except at the lowest coverage measured the spectra indicate rapid proton exchange processes to occur which average out the static dipolar interaction energy.
Photochemistry of Colloidal Semiconductors 28. Photo‐Electron Emission from Cadmium Phosphide Particles in Aqueous Solution
Authors: Haase Markus , Weller Horst , Henglein Arnim
Published: March 2014

Laser illumination (308 nm) of small Cd3P2 particles in aqueous solution leads to the formation of hydrated electrons which are detected by their strong optical absorption. The yield increases with decreasing particle size. A quantum yield of 0.04 electrons per photon absorbed was observed for yellow Cd3P2. The absorption of the holes remaining was also observed. Trapped holes and electrons live several 100 ns on the colloidal particles, their recombination being accompanied by fluorescence. – The photo‐electron emission is a complex two‐photon process. A mechanism is proposed according to which an electron is emitted upon the interaction of the two excitonic states (electron‐hole pairs) produced by successive photon absorptions in a colloidal particle. The first state is already relaxed and acts as a fast recombination center for the delocalized second state, the recombination energy being used for the promotion of an electron into the aqueous solvent. This kind of photo‐electron emission thus follows a mechanism different from the two‐photon reactions yet known in laser photochemistry.
Measurements and Analysis of Excess Enthalpies of Alkyl Acetates + 1‐Chloroalkanes Using the Unifac Model
Authors: Ortega Juan
Published: March 2014

Molar excess enthalpies at 298.15 K and atmospheric pressure are reported for eight binary liquid mixtures of alkyl (methyl and propyl) acetates + 1‐chloroalkanes (pentane, hexane, heptane and octane). The experimental results along with literature data of ethyl acetate with the same 1‐chloroalkanes are examined by a version of the UNIFAC model. In general, the model reproduces the experimental data within the limits of error. The maximum discrepances are observed in those mixtures where the acetate with the largest alkyl radical intervenes; however, the average overall error of the twelve systems analysed here is less than 6.5 per cent.
Recent Advances in the Theory of the Electric Double Layer
Authors: Schmickler Wolfgang
Published: March 2014

Recent progress in the theory of the electric double layer at a metal/solution interface is reviewed. In the absence of specific adsorption the system may be represented as jellium in contact with an ensemble of hard sphere ions and dipoles; results of explicit model calculations are compared with experimental data. When ions are specifically adsorbed, the induced change in the surface dipole potential is of particular interest. Due to the effective screening of the adsorbate charge by the solvent and by the metal electrons, the corresponding dipole moments are relatively small. Finally, isotherms for ionic adsorption are considered in the limit of vanishing bulk concentration.
Thin Films of Conjugated Polymers for Photoelectrochemical and Electronic Devices
Authors: Garnier Francis , Horowitz Gilles , Roncali Jean , Lemaire Marc
Published: March 2014

Organic conjugated polymers can be deposited as thin films on semiconducting or conducting electrodes, and, owing to the large potential offered by varying their physical and chemical properties, new devices can be envisionned. Thus CdS and CdSe are interesting photoanodes for the photoelectrochemical conversion and storage of light energy, but they require to be protected against their very fast corrosion in aqueous solution. This is achieved by thin layers of composite conducting polymers, in which the conductivity the catalytic activity and the hydrophobic character can be controlled. Besides, conjugated polymer films possess in their undoped state semiconducting properties, and when deposited on inorganic semiconductors, they lead to new “organic‐on‐inorganic” electronic junctions. The electric characteristics of these junctions can be easily tuned by subtle chemical modifications in the polymer structure and doping level. Finally, the recent development of functionalized organic conducting polymers, in which various prosthetic groups bearing selective functions are homogeneously distributed along the conducting chains, will allow the realization of new chemically selective electronic devices.
Oxygen Reduction Electrocatalysis by Chevrel Phase Sulfides Supported on Carbon Paste Electrodes
Authors: Schubert B. , Vante N. Alonso , Gocke E. , Tributsch H.
Published: March 2014

Molecular oxygen reduction studies in acid medium have been performed with cluster materials of the Chevrel phase type supported on carbon paste electrodes. It was found that the metal intercalated in the channels between Mo6 clusters enhances their catalytic activity. This is explained by the formation, during oxygen reduction, of peroxo intermediates bonded both to the transition metal cluster and to the intercalated atom. The advantage of the resulting bimetallic catalysis is even more pronounced using mixed clusters. The increasing activity of differently intercalated cluster materials can be correlated with their structural parameters.
Elektrochemie neuer Speichersysteme
Authors: Beck F.
Published: March 2014

Chemistry and material science predominate in the development of new storage batteries. Nevertheless, no perspective systematics is possible without the fundamental electrochemical aspects. The present review consequently tries to verify this feature and it generally avoids the descirption of individual systems. The industrial state of the art is characterized by energy densities of about 100 Wh/kg−1 and by satisfying cyclabilities.
Electron Spectroscopic and Electrochemical Investigations of Chemically Modified Iron Surfaces
Authors: Volmer M. , Czodrowski B. , Stratmann M.
Published: March 2014

Iron surfaces, chemically modified by n‐decanethiol (n‐DMc), have been investigated in order to get a better understanding of the corrosion protection of reactive metals by organic coatings, as investigations of the phase boundary substrate/organic coating are possible only if just monolayers of an organic monomere are adsorbed onto the metal. Electron spectroscopic (XPS, AES) and electrochemical analyses (cyclovoltammetry, rotating ring‐disc‐electrode) have shown that a stable bond between iron and n‐DMc and a well defined orientation of the organic molecules towards the surface are only observed, if the thiol is adsorbed at an oxid free substrate. In this case the oxidation of the thiol by air to disulfide, sulfenate, and sulfonate is highly inhibited. Similar results are obtained regarding the electrode reactions like metal dissolution/passivation, and H+‐reduction in an Ar‐purged borate buffer (pH = 8.5). Only oxygen can be reduced on the modified surface with high rates, the kinetics being completely different from the one on clean iron surfaces. It is proposed, that as part of the O2‐reduction the thiol is transformed into disulfide, which then catalyses the oxygen reduction but still inhibits the rate of metal dissolution and H+‐reduction. After prolonged O2‐reduction the disulfide is oxidized to sulfonate, which then desorbs from the metal surface.
Impedance Analysis of Quartz Oscillators, Contacted on One Side with a Liquid
Authors: Beck Ralf , Pittermann Udo , Weil Konrad G.
Published: March 2014

We use a vector analyzer to investigate the impedance of a quartz oscillator, one face of which is exposed to a liquid. An aqueous LiCl – solution can be used to vary density and viscosity of the liquid over a wide range. The solution acts as an additional impedance with as well a real as an imaginary part. Furthermore, different electrical driver circuits have been used to excite the crystal vibrations. In most cases, our experimental results deviate from the predicted dependence of the crystal frequency from density and viscosity. These deviations are different for different driving circuits, but they do not change with the properties of the liquid.
The Dependence of the Redox Potentials in the System Ru[(CnH2n+1)2bpy]23+/3+ /Methylviologen2+/+ on the Hydrocarbon Chain Length and on the Ratio of Water and Acetonitrile in the Solvent
Authors: Greiner G. , Wörner M. , Rau H.
Published: March 2014

The redox potentials of hydrocarbon‐substituted Ru[(CnH2n+1)2bpy]3 complexes with n = 0, 1, 5 and 7 have been measured with cyclic voltammetry in acetonitrile. There is a marked decrease of the redox potential on substitution but the chain length has no strong effect. The free enthalpy of electron transfer for the reaction between the oxidized complexes and reduced methylviologen RuL33+ + MV+ → RuL23+ + MV2+ has been obtained by differential pulse voltammetric measurements of the redox partners in the same solutions of different water/acetonitrile composition. The electron transfer is less exergonic for the substituted complexes and there is a minimum in the ΔG° vs. χ plots for the unsubstituted and methyl‐substituted complex. The effect of the supporting electrolyte on ΔG0 is shown for the methyl‐substituted complex. The relevance of these results for the photoinduced electron transfer reaction is pointed out.
Electrochemical and Structural Behaviour of Pd+ Implanted TiO2‐Films in Dependence on the Pd+‐Concentration
Authors: Elfenthal L. , Schultze J. W. , Delplancke J.‐L.
Published: March 2014

According to our recent investigations, ion implantation into oxide films yields an increase in capacity, an enhancement of ETR and a decrease in the band gap. These effects are now measured in dependence on the implanted Pd+‐concentration. Due to doping or metallization by Pd as well as to radiation damage and amorphization, the implantation effects increase up to 1 to 3% Pd+ but then saturation is observed. Saturation of amorphization is due to fast annihilation of the Frenkel defects during implantation, but saturation of doping by Pd may be caused by the Pd‐cluster formation. The defect states of the oxide films can be annihilated during the andic polarization (repassivation). – The interface Ti/TiO2 is mixed by the implanted Pd+‐ions. The surface structure and grain boundaries of the oxide films disappear during Pd+‐implantation. This can be seen with Scanning Electron Microscopy and measured by localized photocurrent and Transmission Electron Microscopy. The implanted films are reconstructed by repassivation, and an additional oxide is grown at the interfaces of the oxide. The latter can be concluded from Rutherford Backscattering Spectroscopy (RBS). The Pd‐enrichment at the surface, at intermediate repassivation potentials, is measured by X‐ray Photoelectron Spectroscopy (XPS) and it can be correlated exactly with the results of ETR experiments. XPS ad RBS show that all implanted Pd+ disappears during repassivation up to the oxide formation potential.
Forces and Torques Acting on Two Parallel Dielectric Cylinders in a Periodic Transverse Field. B. Frequency Dependence
Authors: Schlögl Reinhard W.
Published: March 2014

The frequency dependence of forces and torques acting on two parallel cylinders in a periodic field is investigated. The permittivities are assumed to have imaginary parts a) due to an electric conductance or b) due to a single Debye relaxation. At the transition frequencies a change of the sign of the force components or of the torque can take place. Marked deviations from the “long distance laws” occur for small cylinder distances.
Photochemistry of Azide Complexes of Gold, Silver, Platinum, and Palladium. Generation of the Metallic State
Authors: Vogler A. , Quett C. , Kunkely H.
Published: March 2014

The photochemistry of the following azide complexes in organic solvents has been investigated: [Au(N3)4]−, [Au(N3)2]−, [Ag(PPh3)2N3], [Pt(N3)6]2, [Pt(N3)4]2−, [Pd(N3)4]2−, and [Pd2(N3)6]2−. All complexes underwent a photochemical reduction of the metal and oxidation of azide upon ligand to metal charge transfer excitation. The photolysis of the complexes with the metals in the lower oxidation states (Au(I), Ag(I), Pt(II), Pd(II)) led ultimately to the generation of free metals which form colloids. These colloids were characterized by their absorption spectra which showed the typical plasmon bands in the case of gold and silver. Pt(0) and Pd(0) produced during the photolysis can be intercepted with allyl chloride to form [Pt(π‐allyl)Cl]4 and [Pd(π‐allyl)Cl]2. Most photoreactions took place with rather large quantum yields.
Synthesis of highly luminescent mercaptosuccinic acid‐coated CdSe nanocrystals under atmospheric conditions
Authors: Dong Meiting , Xu Jingyi , Liu Shuxian , Zhou Ying , Huang Chaobiao
Published: March 2014

Here we report a facile one‐pot method for the preparation of high‐quality CdSe nanocrystals (NCs) in aqueous solution under an air atmosphere. Compared with the traditional use of NaHSe or H2Se, the more stable sodium selenite is utilized as the Se source for preparing highly luminescent CdSe nanocrystals. By using mercaptosuccinic acid (MSA) as the capping agent and borate–citrate acid as the buffering solution, CdSe nanocrystals with high quantum yield (up to 70%) have been synthesized conveniently. The influence of different experimental parameters, such as the pH of the precursor solution, the molar ratio of Cd2+ to Na2SeO3 and Cd2+ to MSA on the CdSe nanocrystals, has been systematically investigated. The prepared CdSe NCs were spherical with a size of ~ 5 nm. Copyright © 2014 John Wiley & Sons, Ltd.
Most lobular carcinoma in situ and atypical lobular hyperplasia diagnosed on core needle biopsy can be managed clinically with radiologic follow‐up in a multidisciplinary setting
Authors: Middleton Lavinia P. , Sneige Nour , Coyne Robin , Shen Yu , Dong Wenli , Dempsey Peter , Bevers Therese B.
Published: March 2014

We evaluated the efficacy of using standard radiologic and histologic criteria to guide the follow‐up of patients with lobular carcinoma in situ (LCIS), lobular neoplasia (LN), or atypical lobular hyperplasia (ALH). Patients with high‐risk benign lesions diagnosed on biopsy were presented and reviewed in a multidisciplinary clinical management conference from 1 November 2003 through September 2011. Associations between patient characteristics and rates of upgrade were determined by univariate and multivariate logistic models, and times to diagnosis carcinoma were calculated. Of 853 cases reviewed, 124 (14.5%) were lobular neoplasms. In all, 104 patients were clinically and/or radiographically monitored. In 20 patients, who were found to have LN on core biopsy and were recommended to have immediate surgical excision, a more significant lesion was identified in 8 (40%) of the excised specimens. Factors associated with a more significant lesion on excisional biopsy included whether the lobular lesion had been targeted for biopsy and whether the extent of disease involved three or more terminal duct lobular units. Of the 104 patients radiographically and clinically monitored, the median follow‐up time was 3.4 years with a range of 0.44–8.6 years. Five patients under surveillance were subsequently diagnosed with breast malignancy (three of the five at a site unrelated to the initial biopsy). Patients with incidental lobular lesions identified on percutaneous core needle biopsy have a small risk of upgrade and may not require an excisional biopsy. Clinical management of low‐volume lobular lesions in a multidisciplinary setting is an efficacious alternative to surgical excision when radiologic and histologic characteristics are well‐defined.
The Ca2+‐activated Cl− channel, ANO1 (TMEM16A), is a double‐edged sword in cell proliferation and tumorigenesis
Authors: Qu Zhiqiang , Yao Weicheng , Yao Ruyong , Liu Xiangping , Yu Kuai , Hartzell Criss
Published: March 2014

Since anoctamin 1 ANO1 (TMEM16A) was found to be a molecular component of Ca2+‐activated Cl− channels, its role in tumorigenesis has gained attention at a fast pace. ANO1 overexpression frequently occurs in the cancer tissues along with 11q13 chromosome amplification. Poor prognosis of many types of cancers has been closely correlated with ANO1 gene amplification and protein overexpression. ANO1 is now considered an excellent biomarker for certain cancers. Recent research suggests that it is the channel function of ANO1 that is involved in the tumorigenesis. However, how the overexpression of the functional ANO1 causes malignant transformation of tissues via signaling pathways, for example, MAPK remains to be investigated. Clarification of the reasons in future will avail to make ANO1 as a target for cancer treatment.
Dissecting Physical and Biochemical Factors of Catalytic Effectiveness in Immobilized D‐Amino Acid Oxidase by Real‐Time Sensing of O2 Availability Inside Porous Carriers
Authors: Bolivar Juan M. , Schelch Sabine , Mayr Torsten , Nidetzky Bernd
Published: March 2014

D‐Amino acid oxidase (DAAO) presents a paragon for effective use of biocatalytic O2‐dependent transformations in fine‐chemical and pharmaceutical synthesis at the industrial scale. Solid‐supported DAAO immobilizates are applied to continuous processing, but their activity and stability are often inadequate. Targeted immobilization development is restricted by insufficient knowledge of physical and biochemical factors governing the performance of heterogeneous DAAO catalysts. We have applied real‐time optical sensing of the O2 availability in luminescence‐labeled porous Sepabeads and ReliSorb carriers to quantify diffusional restrictions in DAAO immobilizates differing in the mode of enzyme attachment to the solid surface. We show that noncovalent oriented immobilization of DAAO (from Trigonopsis variabilis) resulted in high retention of the original enzyme activity (≥60 %), whereas covalent multipoint fixation caused massive (up to 90 %) activity loss. Depletion of O2 inside the solid immobilizates became limiting for enzyme catalytic effectiveness at activity loadings as low as 5 units gcarrier−1. Slow pore diffusion was principally responsible for the observed large mass‐transfer resistance, and this provides a main starting point for process intensification.
Stability and CO2 Capture Ability of Electrogenerated N‐Heterocyclic Carbene in Parent 1‐Butyl‐3‐methylimidazoliun Ionic Liquid (BMIm‐X): The Role of X−
Authors: Feroci Marta , Chiarotto Isabella , Forte Gianpiero , Vecchio Ciprioti Stefano , Inesi Achille
Published: March 2014

The electrochemical reduction of imidazolium‐based ionic liquids (BMIm‐X) leads to the formation of corresponding N‐heterocyclic carbenes (NHCs). Owing to the peculiar reactivity of NHCs, solutions containing NHC in ionic liquid (IL) can be used in CO2 capture or in organocatalyzed reactions. It is thus important to know the stability of the carbene in the parent IL. In fact, the NHC lifetime can be influenced by the nature of the anion (X−) of the IL. To better understand the relationship between NHC lifetime (and reactivity towards CO2) and IL medium, the presence of electrogenerated NHC in the parent IL is studied by using voltammetric, infrared, and thermogravimetric analyses and by isolation of the adduct between NHC and benzaldehyde. It is thus possible to estimate the actual NHC concentration and its lifetime through voltammetric peak‐current measurements. Moreover, NHC in BMIm‐X is able to catch CO2 (yielding the adduct NHC–CO2) and, triggered by heating (60‐150 °C), to release CO2. It is proven that the half‐life of NHC and the rate of CO2 capture are both affected by the nature of X−.
Solid‐State Interconversions: Unique 100 % Reversible Transformations between the Ground and Metastable States in Single‐Crystals of a Series of Nickel(II) Nitro Complexes
Authors: Warren Mark R. , Easun Timothy L. , Brayshaw Simon K. , Deeth Robert J. , George Michael W. , Johnson Andrew L. , Schiffers Stefanie , Teat Simon J. , Warren Anna J. , Warren John E. , Wilson Chick C. , Woodall Christopher H. , Raithby Paul R.
Published: March 2014

The solid‐state, low‐temperature linkage isomerism in a series of five square planar group 10 phosphino nitro complexes have been investigated by a combination of photocrystallographic experiments, Raman spectroscopy and computer modelling. The factors influencing the reversible solid‐state interconversion between the nitro and nitrito structural isomers have also been investigated, providing insight into the dynamics of this process. The cis‐[Ni(dcpe)(NO2)2] (1) and cis‐[Ni(dppe)(NO2)2] (2) complexes show reversible 100 % interconversion between the η1‐NO2 nitro isomer and the η1‐ONO nitrito form when single‐crystals are irradiated with 400 nm light at 100 K. Variable temperature photocrystallographic studies for these complexes established that the metastable nitrito isomer reverted to the ground‐state nitro isomer at temperatures above 180 K. By comparison, the related trans complex [Ni(PCy3)2(NO2)2] (3) showed 82 % conversion under the same experimental conditions at 100 K. The level of conversion to the metastable nitrito isomers is further reduced when the nickel centre is replaced by palladium or platinum. Prolonged irradiation of the trans‐[Pd(PCy3)2(NO2)2] (4) and trans‐[Pt(PCy3)2(NO2)2] (5) with 400 nm light gives reversible conversions of 44 and 27 %, respectively, consistent with the slower kinetics associated with the heavier members of group 10. The mechanism of the interconversion has been investigated by theoretical calculations based on the model complex [Ni(dmpe)Cl(NO2)].
Catalytic Water Splitting with an Iridium Carbene Complex: A Theoretical Study
Authors: Venturini Alessandro , Barbieri Andrea , Reek Joost N. H. , Hetterscheid Dennis G. H.
Published: March 2014

Catalytic water oxidation at Ir(OH)+ (Ir=IrCp*(Me2NHC), where Cp*=pentamethylcyclopentadienyl and Me2NHC=N,N′‐dimethylimidazolin‐2‐ylidene) can occur through various competing channels. A potential‐energy surface showing these various multichannel reaction pathways provides a picture of how their importance can be influenced by changes in the oxidant potential. In the most favourable calculated mechanism, water oxidation occurs via a pathway that includes four sequential oxidation steps, prior to formation of the OO bond. The first three oxidation steps are exothermic upon treatment with cerium ammonium nitrate and lead to formation of IrV(O)(O.)+, which is calculated to be the most stabile species under these conditions, whereas the fourth oxidation step is the potential‐energy‐determining step. OO bond formation takes place by coupling of the two oxo ligands along a direct pathway in the rate‐limiting step. Dissociation of dioxygen occurs in two sequential steps, regenerating the starting material Ir(OH)+. The calculated mechanism fits well with the experimentally observed rate law: v=kobs[Ir][oxidant]. The calculated effective barrier of 24.6 kcal mol−1 fits well with the observed turnover frequency of 0.88 s−1. Under strongly oxidative conditions, OO bond formation after four sequential oxidation steps is the preferred pathway, whereas under milder conditions OO bond formation after three sequential oxidation steps becomes competitive.
Photodynamic Therapy Efficacy Enhanced by Dynamics: The Role of Charge Transfer and Photostability in the Selection of Photosensitizers
Authors: Arnaut Luis G. , Pereira Mariette M. , Dąbrowski Janusz M. , Silva Elsa F. F. , Schaberle Fábio A. , Abreu Artur R. , Rocha Luís B. , Barsan Madalina M. , Urbańska Krystyna , Stochel Grażyna , Brett Christopher M. A.
Published: March 2014

Progress in the photodynamic therapy (PDT) of cancer should benefit from a rationale to predict the most efficient of a series of photosensitizers that strongly absorb light in the phototherapeutic window (650–800 nm) and efficiently generate reactive oxygen species (ROS=singlet oxygen and oxygen‐centered radicals). We show that the ratios between the triplet photosensitizer–O2 interaction rate constant (kD) and the photosensitizer decomposition rate constant (kd), kD/kd, determine the relative photodynamic activities of photosensitizers against various cancer cells. The same efficacy trend is observed in vivo with DBA/2 mice bearing S91 melanoma tumors. The PDT efficacy intimately depends on the dynamics of photosensitizer–oxygen interactions: charge transfer to molecular oxygen with generation of both singlet oxygen and superoxide ion (high kD) must be tempered by photostability (low kd). These properties depend on the oxidation potential of the photosensitizer and are suitably combined in a new fluorinated sulfonamide bacteriochlorin, motivated by the rationale.
A Cobalt Pyrenylnitronylnitroxide Single‐Chain Magnet with High Coercivity and Record Blocking Temperature
Authors: Vaz Maria G. F. , Cassaro Rafael A. Allão , Akpinar Handan , Schlueter John A. , Lahti Paul M. , Novak Miguel A.
Published: March 2014

Coordination of a [Co(hfac)2] moiety (hfac=hexafluoroacetylacetonate) with a nitronylnitroxide radical linked to bulky, rigid pyrene (PyrNN) gives a helical 1:1 chain complex, in which both oxygen atoms of the radical NO. groups are bonded to CoII ions with strong antiferromagnetic exchange. The complex shows single‐chain magnet (SCM) behavior with frequency‐dependent magnetic susceptibility, field‐cooled and zero‐field‐cooled susceptibility divergence with a high blocking temperature of around 14 K (a record among SCMs), and hysteresis with a very large coercivity of 32 kOe at 8 K. The magnetic behavior is partly related to good chain isolation induced by the large pyrene units. Two magnetic relaxation processes have been observed, a slower one attributable to longer, and a faster one attributable to short chains. No evidence of magnetic ordering has been found.
Efficiently Detecting Metallodrug–Protein Adducts: Ion Trap versus Time‐of‐Flight Mass Analyzers
Authors: Meier Samuel M. , Babak Maria V. , Keppler Bernhard K. , Hartinger Christian G.
Published: March 2014

Modern mass spectrometry techniques have increasingly found use in studies on the binding of anticancer metallodrugs to potential cellular targets. In this context, investigations on the detection efficiency of adduct formation between antiproliferative Ru(arene) complexes and proteins in dependence of the mass analyzer used in the electrospray ionization (ESI) mass spectrometer are presented. The potential in detecting adducts between the metal center and the protein was found to be dependent on the mass analyzer and the denticity of the metal–protein interaction. This might be related to the design of the mass analyzers with different conditions in the ion travelling pathways, which affects adducts when the protein acts as a monodentate ligand more highly than in cases when the protein is a multidentate ligand. This could also impact the biological activity and indicate different pathways of metabolism of biomolecule adducts.
Adherence and retention in clinical trials: A community‐based approach
Authors: Fouad Mona N. , Johnson Rhoda E. , Nagy M. Christine , Person Sharina D. , Partridge Edward E.
Published: March 2014

BACKGROUND

The Community Health Advisor (CHA) model has been widely used to recruit rural and low‐income, mostly African American women into clinical and behavioral research studies. However, little is known about its effectiveness in promoting retention and adherence of such women in clinical trials.

METHODS

The Community‐Based Retention Intervention Study evaluated the effectiveness of a community‐based intervention strategy using the CHA model and the empowerment theory to improve the retention and adherence of minority and low‐income women in clinical trials. The research strategy included the training and use of the volunteer CHAs as research partners. The target population included women participating in the University of Alabama at Birmingham clinical site of the Atypical Squamous Cells of Undetermined Significance–Low‐Grade Squamous Intraepithelial Lesion (ASCUS‐LSIL) Triage Study (ALTS), a multicenter, randomized clinical trial. Two communities in Jefferson County, Alabama, that were matched according to population demographics were identified and randomly assigned to either an intervention group or a control group. Thirty community volunteers were recruited to be CHAs and to implement the intervention with the ALTS trial participants. In total, 632 ALTS participants agreed to participate in the project, including 359 in the intervention group, which received CHA care, and 273 in the control group, which received standard care.

RESULTS

Adherence rates for scheduled clinic visits were significantly higher in the intervention group (80%) compared with the control group (65%; P < .0001).

CONCLUSIONS

The results indicate that volunteer CHAs can be trained to serve as research partners and can be effective in improving the retention and adherence of minority and low‐income women in clinical trials. Cancer 2014;120(7 suppl):1106–12. © 2014 American Cancer Society.