bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Modelling of Gasphase Aromatisation in the Pyrolysis of Hydrocarbons (Part II)
Authors: Stabel U. , Ederer H. J. , Ebert K. H. 
Published: July 2012

AbstractThe kinetics of the thermal decomposition of n‐hexane and some hydrocarbon mixtures was studied experimentally in respect to the homogeneous formation of aromatics. Some 60 reaction products were identified, among them a number of precursor substances. An attempt has been made to extend our previous reaction model for the mathematical simulation of n‐hexane gas phase pyrolysis by addition of detailed pathways for the formation of benzene and toluene.
Oscillations and Coupling Phenomena Between Different Areas of the Catalyst During the Heterogeneous Catalytic Oxidation of Ethanol
Authors: Jaeger N. I. , Ottensmeyer R. , Plath P. J. 
Published: July 2012

AbstractThe heterogeneously catalyzed oxidation of ethanol was found to be a new chemical system, which exhibits oscillatory behavior. Experiments were carried out using a continuous flow calorimeter and an amorphous alumina‐supported Palladium catalyst.—Temperature as well as product oscillations are presented. Detailed measurements of the temperature of the catalyst reveal coupling and decoupling phenomena between different synchronized areas of the catalyst bed. On the basis of the phase relation between product oscillations possible mechanisms are discussed.
Static and MAS 35CI NMR and Molecular Motions of ClO Ions in the Various Phases of Multimethylammonium Perchlorates
Authors: Jurga S. , Harbison G. S. , Blümich B. , Spiess H. W. , Fujara F. , Olinger A. 
Published: July 2012

AbstractStatic and MAS*) 35CI NMR data of CIO−4 ions in the low‐, intermediate‐ and high‐temperature phases of trimethylammonium, dimethylammonium and monomethylammonium perchlorates are reported. The observed solid‐solid phase transitions are interrelated with the motional state of the perchlorate ions. In the low‐temperature phase III of trimethylammonium perchlorate there is an anisotropic motion of the ClO−4 ions with a constant quadrupole frequency of 185 kHz and an increasing value of the asymmetry parameter when approaching phase transition III‐II. The activation energy for this motion is found to be 44.3 kj/mol. At the transition III‐II the ClO−4 ions gain orientational degrees of freedom manifested by the change of the quadrupole frequency to 159 kHz. In phase II the perchlorate ions undergo an axial motion overcoming the energy barrier of 40.7 kj/mol. In the low‐temperature phase III of dimethylammonium perchlorate there are rigid ClO−4 ions. At the phase transition III‐II the ClO−4 ions gain considerable motional freedom indicated by lowering the quadrupole frequency to 119 kHz, due to an anisotropic motion. In the high‐temperature phase I the anions undergo isotropic motion with the activation energy of 11.9 kj/mol. The low‐temperature phase III of monomethylammonium perchlorate is characterized by rigid ClO−4 ions. At the transition III‐II the ClO−4 ions gain a considerable motional freedom and undergo an axial motion in phase II. In phase I motion of the anions is isotropic. The motional behaviour of the anions along with NMR data for the cations suggests that the low‐temperature ordering of the ions in phase HI is due to hydrogen‐bonds NH … OCl, the partial breaking of which, accompanied by the phase transition III‐II, leads to an axial motion of the ions in phase II. A complete breaking of all hydrogen‐bonds in phase I allows the ions to reorient isotropically. The quadrupole coupling constant of rigid ClO−4 ions amounts to about 1 MHz.
Molecular Structure Determination Inferred from Highly Resolved 4A2g ↔ 2Eg, 2T1g Spectra and Ligand Field Calculations of Trigonally Distorted Hexaamminechromate(III)
Authors: Urushiyama Akio , Schönherr Thomas , Schmidtke Hans‐Herbert 
Published: July 2012

AbstractHighly resolved vibronic spectra were measured at helium temperatures due to spin‐forbidden 4A2g ↔ 2Eg, 2T1g d—d transitions of hexaamminechromate(III) salts. Almost complete assignments of the detailed vibrational structure are presented including the band positions of all five spin‐orbit electronic origins of S6. The electronic level schemes can be rationalized by conventional ligand field calculations because for NH3‐ligands no π‐bonding is involved. From the electronic level splittings polar angles of trigonal distortions from CrN6 octahedra were determined to be Δα = 0.19° for the CdC‐salt, and 0.23° for the analogous copper compound. The phosphorescence spectra exhibit progressions mainly in the Jahn‐Teller active mode ν2(eg); from relative band intensities, bond length changes of the emitting excited state by a few mÅ are calculated.
Fe/Mn Oxide Catalysts for Fischer‐Tropsch‐Synthesis Part VII: Adsorption of Carbon Monoxide and Nitrogen at Low Temperatures
Authors: Hess D. , Papp H. , Baerns M. 
Published: July 2012

AbstractIron/manganese oxides often used as catalysts for the Fischer‐Tropsch (FT) hydrogenation of CO have been characterized by their adsorption properties. N2 physisorption was carried out at 77 K and CO chemisorption at 194 K in a vacuum microbalance. Precipitated solids with compositions ranging from pure iron oxide to pure manganese oxide were studied after calcination and reduction. The results indicate a correlation between the fraction of metallic iron in the surface, the irreversible chemisorption of CO at 194 K and the initial activity for FT synthesis.
Thermodynamic properties of molten Na‐Te solutions
Authors: Petric Anthony , Pelton Arthur D. , Saboungi Marie‐Louise 
Published: July 2012

AbstractThermodynamic properties of liquid Na‐Te solutions were measured over the range 0–52 at.% Na at temperatures between 573 and 873 K by means of alloy concentration cells. Beta alumina was used as the solid electrolyte. The following properties were derived from the emf data: ΔG, ΔH, ΔS, the excess heat capacity CE p and the excess stability, ES. The Gibbs energy, enthalpy and entropy showed marked negative deviations. The plot of excess stability versus composition exhibits a rather flat shoulder between 10 and 20 at.% Na and a broad maximum or shoulder near 50% Na indicating maximum short‐range ordering near these compositions. Liquidus and invariant points on the phase diagram as well as the Gibbs energies of formation of the solid compounds NaTe3, NaTe and Na2Te have also been determined.
Mixtures with “w‐Shape” CEp curves. A light scattering study
Authors: Rubio Ramón G. , Cáceres Mercedes , Masegosa Rosa M. , Andreolli‐Ball Lina , Costas Miguel , Patterson Donald 
Published: July 2012

AbstractThe Rayleigh ratio has been obtained for the following mixtures of non‐electrolytes that show “w‐shape” CEp vs. x curves: Nitrobenzene + n‐Heptane, 1,4‐Dichlorobutane + n‐Heptane and Acetone + n‐Dodecane. From them, the concentration‐concentration correlation function Scc(0) has been calculated, as well as the excess Gibbs energy. It has been found that a clear tendency to homocoordination is present in all the mixtures studied. There is a rough correspondence between the concentration at which the maximum of the Scc(0) curves occur and those at which the negative curvature regions exist in the CEp curves. Also the larger the value of max. Scc(0) the more intense the “w‐shape” effect. Despite size differences between the components and specific interactions which complicate the connection between Scc(0) and CEp, an analysis in terms of simple mean field models supports the view that the systems which show “w‐shape” CEp curves still feel the effects of the more or less distant UCST. Hence Scc(0) is proposed as an indicator of the “w‐shape” CEp.
Laser‐tissue interactions
Authors: Srinivasan R. 
Published: July 2012

AbstractThe interactions of laser radiation with animal tissue have become a vast field of study. The detailed chemical behavior of the photons with the tissue, while scientifically a fascinating topic for investigation, is difficult to study experimentally. We have used synthetic polymers and small molecules in the condensed phase as models for the study of non‐linear photochemistry of all organic systems. While such extrapolations should always be used with caution, they have been helpful in suggesting new strategies for tissue ablation which may be adaptable to experiments in vivo. —In etching and ablation by pulsed ultraviolet lasers, the power density at the surface of the polymer or tissue is critical in determining the threshold for ablation and the etch depth per pulse at photon fluxes greater than the threshold. This has been explained by a mechanism in which a single chromophore is excited to high electronic levels by the successive absorption of two or more photons. Recent experiments have been directed towards the use of pairs of laser pulses with a preset time interval separating them in order to couple the multi‐photon excitation process to the excited states of the chromophores in the solid in an optimum fashion. The initial results suggest that a certain amount of “tuning” of the laser pulse to suit the ablation kinetics of the substrate is not only possible but may be useful in practical applications of UV laser: tissue interactions.
Laser in medicine
Authors: Senz R. , Müller G. 
Published: July 2012

AbstractBetween 1965 and 1980 basic research into the medical use of lasers led to the discovery of new applications. Today we differentiate between three classes of principle interactions. Firstly there are the photochemical effects whereby laser energy is used to trigger off photochemical reactions on biomolecules by absorption of either natural or artificial dyes, or chromophoric groups. This is one of the basic principles of nature, e.g. photosynthesis and the vision process. —A further effect is based on the fact that the absorption of light at a suitable wavelength and intensity is converted into heat which accordingly leads to a heating effect of the irradiated tissue. It is a thermal effect whereby the result is dependent on the degree of absorption and the amount of radiation absorbed. In this way photocoagulation and tissue cutting is possible. —The third effect can be summarized under the term “non‐linear effects”, as they cannot be explained by the linear absorption of photons, i.e. radiation, and therefore are classified according to the effects that they produce. It is possible by these non‐linear effects to remove material fragments from the surface by light without heating the surrounding area. —Between the above mentioned thermal effects, there are the so‐called “photoacoustic effects”. Thermal absorption and time behaviour of the light radiation leads to changes in the acoustic and thermal density which results in the destruction of material. —The laser may contribute in future to solving the following problems: Recanalisation of arterial blood vessels; Destruction or fragmentation of stones in the kidneys, bladder, efferent urinary tracts as well as in the bilary tract; photochemical reactions by choosing the applicable laser wavelength, e.g. polymerisation of biocompatible plastics “in situ”.
Time resolved fluorescence quenching‐experiments on tryptophan and tyrosine containing proteins
Authors: Kühn Klaus P. , Ludwig Horst , Brecht Andreas , Schwarzwald Ralf , Greulich Karl Otto 
Published: July 2012

AbstractThe protein rop, some of its mutants and the human complement component C9 were studied using steady state fluorescence spectroscopy and lifetime resolved fluorescence quenching experiments. —The rop molecule has a hairpin like structure and a tail consisting of 7 amino acids, which is not visible in the electron density map of X‐ray crystallography. The lifetime resolved quenching experiments show that at low salt concentrations the tail is attached to the main body of the molecule, while it is removed at high salt concentrations. This difference can be explained by shielding of electrostatic interactions at high salt. —A comparision of C9 and its polymer with respect to their fluorescence quantum yields and fluorescence lifetimes shows that in the poly C9 three of the four tryptophanes are quenched by intramolecular processes. Furthermore the experiments reveal a discrepancy between exposure of tryptophan determined by the emission spectrum or determined by use of the surface quenchers I− and Cs+.
An Experimental Study of the Reactions CH3CHO + Cl, C2H4O + Cl, and C2H4O + F in the Gas‐Phase
Authors: Bartels M. , Hoyermann K. , Lange U. 
Published: July 2012

AbstractThe reactions of chlorine and fluorine atoms with the structural isomers CH3CHO and C2H4O have been studied at low pressures and room temperature by the discharge flow technique with mass spectrometric detection. Using the reference reactions magnified image the relative rate constant for the reactions magnified image were determined: k1/k0 = 1.04 ± 0.09, k2/k0 = 0.49 ± 0.04, k3/k00 = 0.47 ± 0.05. — Reaction (1) proceeds mainly via hydrogen abstraction from the aldehyde group (> 93%) forming CH3CO. In the reactions of ethylene oxide (2), (3) the abstraction route is observed, contributions from addition channels in reaction (2) are discussed.
Gas‐Phase Dimerization of Sodium Halides and Formation of Mixed Sodium/Phenyl Iodides
Authors: Alkemade U. , Homann K. H. 
Published: July 2012

AbstractThe formation of dimers and oligomers of the monomeric sodium halides NaCl, NaBr and NaI were studied in a flow reactor at a pressure of 300 Pa and temperatures of 623 and 645 K. The reactions propynyl chloride/bromide + Na vapour were used to generate the gaseous NaCl and NaBr while the sodium iodide monomer was formed via the reaction Na + CH3I. The rate constants for the dimerizations of NaCl, NaBr and NaI were found to be 8.0 · 1013, 5.0 · 1013 and 5.0 · 1012 cm3 mol‐1 s‐1, respectively. Under the experimental conditions the dimerizations were near their high‐pressure limits. NaCl oligomers up to [NaCl]5 were detected while the detection of NaBr oligomers was limited by the accessible mass range to [NaBr]3. — In the system Na + Phenyliodide (PhI) mixed Na/Phenyliodides were formed but hardly any NaI. Disodium‐phenyliodide was a main product. Higher compounds such as Na3Ph2J and Na3PhI2 were also detected in lower concentrations. In addition, diphenyl was a product of a homogeneous reaction while benzene was formed both by a heterogeneous and a homogeneous reaction. The reaction mechanism is discussed on the basis of an intermediate complex Na + PhI → NaPhI.
Electrical and Dielectric Behaviour at the Critical Point of Binary Liquids: Acetonitrile + Cyclohexane
Authors: Jayalakshmi V. , Guha S. , Gopal E. S. R. 
Published: July 2012

AbstractThe electrical capacitance and resistance of the binary liquid mixture cyclohexane + acetonitrile are measured in the one phase and two phase regions at spot frequencies between 5 kHz and 100 kHz. This sample has a very low gravity affected (∼0.6 mK) region. In one phase region the capacitance data show a sharp, ∼0.7% increase above background within 0.5 degrees of Tc whereas the resistance has a smooth increase of ∼1.5% above background in a (T−Tc) range of 4 degrees. Two phase values of capacitance and resistance from the coexisting phases are used to determine the critical parameters Tc (critical temperature), Rc (resistance at Tc) and Cc (capacitance at Tc). A precise knowledge of these parameters reduces the uncertainty on the critical exponent 0 for C and R. The one phase capacitance data fit to an (1 ‐ α) exponent in a limited temperature range of 0.2 degrees. Resistance data strongly support an (1 ‐ α) exponent over the entire 5 degree range.
Solvent induced intramolecular electron exchange kinetics in 1,3‐isodisubstituted aromatic radical anions I. ESR‐measurements at 280 K
Authors: Grampp G. , Shohoji M. C. B. L. , Herold B. J. 
Published: July 2012

AbstractThe rate constants of the intramolecular solvent induced electron transfer in 1,3‐dinitrobenzene and benzene‐1,3‐dicarbaldehyde radical anions were measured in different solvents by means of ESR‐spectroscopy using the alternating linewidth effect. At 280 K, for benzene‐1,3‐dicarbaldehyde the rate constants are 0.89–1.52·109 s−1 in several alcohols, whereas for the 1,3‐dinitrobenzene radical they are 1.16–2.19–106 s−1 in alcohols and 2.8–4.2·109 s−1 in aprotic solvents. The reactions were found to be adiabatic and uniform in the sense of classical transition state theory. From the solvent dependence of the rate constants, the transferred charge was determined applying Marcus theory as being z = 0.31 for the benzene‐1,3‐dicarbaldehyde, z = 0.84 for the 1,3‐dinitrobenzene radical anion in alcohols and z = 0.51 in aprotic solvents. The ellipsoidal cavity model was employed for evaluating the outer sphere reorganization energy λ0.
A cloud computing system in windows azure platform for data analysis of crystalline materials
Authors: Xing Qi , Blaisten‐Barojas Estela 
Published: July 2012

SUMMARYCloud computing is attracting the attention of the scientific community. In this paper, we develop a new cloud‐based computing system in the Windows Azure platform that allows users to use the Zeolite Structure Predictor (ZSP) model through a Web browser. The ZSP is a novel machine learning approach for classifying zeolite crystals according to their framework type. The ZSP can categorize entries from the Inorganic Crystal Structure Database into 41 framework types. The novel automated system permits a user to calculate the vector of descriptors used by ZSP and to apply the model using the Random Forest™ algorithm for classifying the input zeolite entries. The workflow presented here integrates executables in Fortran and Python for number crunching with packages such as Weka for data analytics and Jmol for Web‐based atomistic visualization in an interactive compute system accessed through the Web. The compute system is robust and easy to use. Communities of scientists, engineers, and students knowledgeable in Windows‐based computing should find this new workflow attractive and easy to be implemented in scientific scenarios in which the developer needs to combine heterogeneous components. Copyright © 2012 John Wiley & Sons, Ltd.
Contemporary ocean warming and freshwater conditions are related to later sea age at maturity in Atlantic salmon spawning in Norwegian rivers
Authors: Otero Jaime , Jensen Arne J. , L'Abée‐Lund Jan Henning , Stenseth Nils Chr. , Storvik, Geir O. , Vøllestad Leif Asbjørn 
Published: July 2012

AbstractAtlantic salmon populations are reported to be declining throughout its range, raising major management concerns. Variation in adult fish abundance may be due to variation in survival, growth, and timing of life history decisions. Given the complex life history, utilizing highly divergent habitats, the reasons for declines may be multiple and difficult to disentangle. Using recreational angling data of two sea age groups, one‐sea‐winter (1SW) and two‐sea‐winter (2SW) fish originated from the same smolt year class, we show that sea age at maturity of the returns has increased in 59 Norwegian rivers over the cohorts 1991–2005. By means of linear mixed‐effects models we found that the proportion of 1SW fish spawning in Norway has decreased concomitant with the increasing sea surface temperature experienced by the fish in autumn during their first year at sea. Furthermore, the decrease in the proportion of 1SW fish was influenced by freshwater conditions as measured by water discharge during summer months 1 year ahead of seaward migration. These results suggest that part of the variability in age at maturity can be explained by the large‐scale changes occurring in the north‐eastern Atlantic pelagic food web affecting postsmolt growth, and by differences in river conditions influencing presmolt growth rate and later upstream migration.
Socio‐demographic factors and shared leadership behaviors in dispersed teams: Implications for human resource management
Authors: Muethel Miriam , Gehrlein Sarah , Hoegl Martin 
Published: July 2012

AbstractCompanies increasingly make use of geographically dispersed teams to capture knowledge residing at different locations. In this context, shared leadership is considered a key enabler of team performance. Taking a functional perspective on shared leadership, we thus investigate the relationship between shared leadership behaviors and team performance in dispersed teams. Furthermore, we analyze how socio‐demographic factors that are characteristic for dispersed teams (i.e., high female‐to‐male ratio, high mean age, and high levels of national diversity) affect shared leadership behaviors. Based on data from 96 dispersed teams, we show that shared leadership behavior fosters team performance. Further, we find the socio‐demographic characteristics typical for dispersed teams to foster shared leadership. Theoretical and managerial implications for human resource management are discussed. © 2012 Wiley Periodicals, Inc.
Climate changes and their impacts on water resources in semiarid regions: a case study of the Wei River basin, China
Authors: Zhao Guangju , Mu Xingmin , Tian Peng , Wang Fei , Gao Peng 
Published: July 2012

AbstractUnderstanding the impacts of climate change and human activity on the hydrological processes in river basins is important for maintaining ecosystem integrity and sustaining local economic development. The objective of this study was to evaluate the impact of climate variability and human activity on mean annual flow in the Wei River, the largest tributary of the Yellow River. The nonparametric Mann–Kendall test and wavelet transform were applied to detect the variations of hydrometeorological variables in the semiarid Wei River basin in the northwestern China. The identifications were based on streamflow records from 1958 to 2008 at four hydrological stations as well as precipitation and potential evapotranspiration (PET) data from 21 climate stations. A simple method based on Budyko curve was used to evaluate potential impacts of climate change and human activities on mean annual flow. The results show that annual streamflow decreased because of the reduced precipitation and increased PET at most stations. Both annual and seasonal precipitation and PET demonstrated mixed trends of decreasing and increasing, although significant trends (P < 0.05) were consistently detected in spring and autumn at most stations. Significant periodicities of 0.5 and 1 year (P < 0.05) were examined in all the time series. The spectrum of streamflow at the Huaxian station shows insignificant annual cycle during 1971–1975, 1986–1993 and 1996–2008, which is probably resulted from human activities. Climate variability greatly affected water resources in the Beiluo River, whereas human activities (including soil and water conservation, irrigation, reservoirs construction, etc.) accounted more for the changes of streamflow in the area near the Huaxian station during different periods. The results from this article can be used as a reference for water resources planning and management in the semiarid Wei River basin. Copyright © 2012 John Wiley & Sons, Ltd.
Under the influence: An examination of men's fears of women leaders
Authors: Swope Alan J. 
Published: July 2012

AbstractAlthough the number of women leaders in organizations has increased, devaluation of women leaders by men is a persistent problem. The roots of this devaluation are typically discussed in terms of stereotypes and social hierarchy. In this article, I attempt to augment our understanding of this phenomenon by suggesting a psychological explanation, one that posits men's underlying fear of women as a source of devaluation. I draw from studies of men in psychotherapy and research on femiphobia (Kierski & Blazina, 2009) to flesh out the picture of how fears of the feminine still seem to affect men today. I then offer the psychological defense of devaluing and mistrusting those we fear as a tool for understanding male attitudes toward women leaders. Last, I review research on changing men's attitudes and offer a perspective on the modern workplace that integrates the social and psychological perspectives.