bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge Transmission and Recombination in the Dye-Sensitized Solar Cells Based on Mn-Doped TiO2 Thin Films
Authors: Liu Qiu Ping , Zhou Yang , Huang Hui Juan , Guo Quan Jiang , Zhao Xian Hui , Yuan Lin
Published: July 2012

Abstract:Mn salts[MnSO4]-doped TiO2 electrodes thin film was synthesized by the hydrothermal method. To prepare the working electrode, The TiO2 or Mn-doped TiO2 slurry was coated onto the fluorine-doped tin oxide glass substrate by the doctor blade method and was then sintered at 450 °C. X-ray photoelectron spectroscopy (XPS) data indicated that the doped Mn ions exist in forms of Mn7+. This study show a photovoltaic efficiency of 5.15%, which is higher than that of the undoped TiO2 thin film (4.14%) and increase photovoltage and fill factors by 13.2% from 455 mV to 515mV, 39.3% from 499 to 695 respectively.
Microencapsulated Phase Change Materials and its Application in Thermal-Regulated Fibers
Authors: Li Wei , Zhang Xing Xiang , Wang Xue Chen
Published: July 2012

The phase change materials (PCMs) can absorb, store or release large latent heat over a defined temperature range while the materials change phase or state, so they can be potentially used in thermal energy storage. In this paper, a series of microencapsulated phase change materials (MicroPCMs) with n-octadecane and n-dodecanol as core were successfully fabricated respectively, where the styrene-based copolymer, acrylic based copolymer, melamine-formaldehyde resin and polyurea were selected as shell materials. The morphology of these MicroPCMs was observed by scanning electron microscopy (SEM), and the core-shell structure and the shell thickness of microcapsules were also characterized by SEM. In addition, the phase change properties of MicroPCMs were investigated using differential scanning calorimetry (DSC) analysis. Furthermore, thermal-regulated calcium alginate fiber was produced by adding MicroPCMs in wet-spinning process; and the effects of various types of MicroPCMs on fiber was discussed.
Preparation of ZnO Films with Different Morphologies and their Applications in Dye Sensitized Solar Cells
Authors: Wang Yan Xiang , Jian Sun , Zhao Bing Xin
Published: July 2012

The influences of ZnO photoanode structure on the properties of ZnO dye-sensitized solar cell were studied in this paper. Four kinds of ZnO photoanode films prepared from ZnO nanopowders, nanorods, nanosheets and aggregates were investigated. Their photovoltaic parameters were discussed and compared. ZnO cell consisted of ZnO aggregates had optimal properties, photoelectric conversion efficiency, open circuit voltage, short-circuit current and the fill factor of ZnO aggregates cells were 2.15%, 0.64V, 6.47mA•cm-2 and 0.52, respectively.
The Impact Research on Composition and Electric Properties of the CIGS Powder with Different Content of Ga
Authors: Cao Hui Qun , Zhang Xin Peng , Zhang Sheng Jie , Zhang Yi Qian , Hu Ju Guang , Luo Zhong Kuan
Published: July 2012

CuInGaSe2 (CIGS) is the family of semiconducting materials of the tetragonal chalcopyrite structure; it has emerged as a leading material for high efficiency and radiation-hard solar cell application. The CIGS powder was synthesized by a solvothermal method. The morphologies and microstructure of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and inductive coupled plasma (ICP). It was concluded that the powder has different component with the content of Ga in raw changed. SEM results showed that the size of 0.2 ~2m crystal was formed. ICP results indicated that the element molar ratio of Cu, In, Ga and Se is closer to the elements in raw materials when the reactive time is 48h. The electric properties of product have been investigated, and all the samples have small resistivity values.
The evolution of microphysical and optical properties of an A380 contrail in the vortex phase
Authors: Gayet J.-F. , Shcherbakov V. , Voigt C. , Schumann U. , Schäuble D. , Jessberger P. , Petzold A. , Minikin A. , Schlager H. , Dubovik O. , Lapyonok T.
Published: July 2012

Abstract. A contrail from a large-body A380 aircraft at cruise in the humid upper troposphere has been probed with in-situ instruments onboard the DLR research aircraft Falcon. The contrail was sampled during 700 s measurement time at contrail ages of about 1–4 min. The contrail was in the vortex regime during which the primary wake vortices were sinking 270 m below the A380 flight level while the secondary wake remained above. Contrail properties were sampled separately in the primary wake at 90 and 115 s contrail age and nearly continously in the secondary wake at contrail ages from 70 s to 220 s. The scattering phase functions of the contrail particles were measured with a polar nephelometer. The asymmetry parameter derived from these data is used to distinguish between quasi-spherical and aspherical ice particles. In the primary wake, quasi-spherical ice particles were found with concentrations up to 160 cm−3, mean effective diameter Deff of 3.7 μm, maximum extinction of 7.0 km−1, and ice water content (IWC) of 3 mg m−3 at slightly ice-subsaturated conditions. The secondary and primary wakes were separated by an almost particle-free wake vortex gap. The secondary wake contained clearly aspherical contrail ice particles with mean Deff of 4.8 μm, mean (maximum) concentration, extinction, and IWC of 80 (350) cm−3, 1.6 (5.0) km−1, and 2.5 (10) mg m−3, respectively, at conditions apparently above ice-saturation. The asymmetry parameter in the secondary wake decreased with contrail age from 0.87 to 0.80 on average indicating a preferential aspherical ice crystal growth. A retrieval of ice particle habit and size with an inversion code shows that the number fraction of aspherical ice crystals increased from 2% initially to 56% at 4 min contrail age. The observed crystal size and habit differences in the primary and secondary wakes of an up to 4 min old contrail are of interest for understanding ice crystal growth in contrails and their climate impact. Aspherical contrail ice particles cause less radiative forcing than spherical ones.
The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional scale biogeochemical ocean model study
Authors: Lindenthal A. , Langmann B. , Paetsch J. , Lorkowski I. , Hort M.
Published: July 2012

Abstract. In High-Nutrient-Low-Chlorophyll regions, phytoplankton growth is limited by the availability of water soluble iron. Volcanic ash can carry bio-available iron salts on its surface, which may be formed during volcanic eruptions by surface reactions between volcanic gases and ash. The eruption of Kasatochi volcano in August 2008 led to ash deposition into the iron-limited NE Pacific Ocean releasing iron upon contact of volcanic ash with seawater. Atmospheric and oceanic conditions were favourable to generate a massive phytoplankton bloom, which was observed by satellite instruments and in-situ measurements. Here we investigate this event with a regional scale ocean biogeochemical model system to illuminate the ocean response to iron fertilisation by volcanic ash. The results indicate that the added iron triggered an additional phytoplankton bloom in the summer of 2008, which produced a drawdown of carbon dioxide in surface seawater. The simulated development is in good agreement with the available observations.
Regional scale evaluation of a MSG solar radiation product for evapotranspiration modeling
Authors: Cristóbal J. , Anderson M. C.
Published: July 2012

Abstract. Solar radiation plays a key role in the Earth's energy balance and is used as an essential input data in radiation-based evapotranspiration (ET) models. Accurate gridded solar radiation data at high spatial and temporal resolution are needed to retrieve ET over large domains. In this work we present an evaluation at hourly, daily and monthly timesteps and regional scale (Catalonia, NE Iberian Peninsula) of a satellite-based solar radiation product developed by the Land Surface Analysis Satellite Application Facility (LSA SAF) using data from the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI). Product performance and accuracy were evaluated for datasets segmented into two terrain classes (flat and hilly areas) and two atmospheric conditions (clear and cloudy sky), as well as for the full dataset as a whole. Evaluation against measurements made with ground-based pyranometers yielded good results in flat areas with an averaged model RMSE of 65 W m−2 (19%), 1.6 MJ m−2 (9.7%) and 0.9 MJ m−2 (5.6%), for hourly, daily and monthly-averaged solar radiation and including clear and cloudy sky conditions and snow or ice cover. Hilly areas yielded intermediate results with an averaged model RMSE of 89 W m−2 (27%), 2.3 MJ m−2 (14.5%) and 1.4 MJ m−2 (9.3%), for hourly, daily and monthly time steps, suggesting the need for further improvements (e.g., terrain corrections) are required for retrieving localized variability in solar radiation in these areas. In general, the LSA SAF solar radiation product appears to have sufficient accuracy to serve as useful and operative input to evaporative flux retrieval models.
The Emperor's New Clothes?
Authors: Strauss Ekkehard
Published: July 2012

This publication attempts to assist the ongoing discussion on the operationalization of the responsibility to protect by the United Nations. After summarizing the negotiation process towards the agreement in the Summit Outcome Document, the practice of the application of the responsibility to protect by United Nations organs and other bodies since September 2005 is presented, before providing elements for a comprehensive review of existing United Nations capacities to prevent or halt genocide, war crimes, ethnic cleansing and crimes against humanity. Finally, the publication proposes elements for an immediate strategy of the Secretary-General and the United Nations departments, funds and agencies to facilitate the application of the responsibility to protect in practice in the immediate future.
Profesní vidění učitelů: od hledání pojmu k možnostem jeho uchopení
Authors: Minaříková E. , Janík T.
Published: July 2012

Přehledová studie uvádí do českého odborného diskursu profesní vidění jako jeden z perspektivních pojmů využitelných při úvahách na téma (učitelské) profesionalizace. V úvodu textu se autoři zmiňují o vybraných pokusech o vymezení znaků profesí a představují pohled na problematiku učitelské profesionality, který se opírá o tři dimenze – profesní vidění, profesní vědění a profesní jednání. Dále naznačují vztahy mezi těmito třemi dimenzemi, a to v rámci modelu pedagogického uvažování a jednání (Shulman, 1986) a modelu reflexe ALACT (Korthagen, 2011). V dalším textu autoři rozebírají profesní vidění u profesí obecně a poté specificky u učitelů. Představují existující konceptualizace tohoto pojmu a na základě souvisejících teoretických i empirických studií se propracovávají k vlastnímu pojetí profesního vidění učitelů. Dále naznačují vztah profesního vidění a reflexe na spirále pedagogického uvažování a jednání. V závěru nastiňují využití konceptu profesního vidění v učitelském vzdělávání, konkrétně při tvorbě elektronického učebního a diagnostického (video)prostředí pro (budoucí) učitele.
Komparácia profesijných činností slovenských, českých a poľských učiteľov na primárnom stupni školy
Authors: Babiaková S.
Published: July 2012

Cieľom príspevku je porovnať profesijné činnosti učiteľov troch krajín z hľadiska ich časovej záťaže. V úvode autorka venuje pozornosť pojmu profesiografia učiteľa a zameriava sa na súčasné profesiografické výskumy, ktoré boli okrem iného inšpiráciou pre prezentovaný medzinárodný výskum profesijných činností učiteľov. V ďalšej časti príspevku sú načrtnuté výskumné ciele, výskumná stratégia a výskumné nástroje. Autorka v štúdii podrobne rozoberá najmä činnosti priamo súvisiace s vyučovaním a uvádza čas, ktorý im učitelia primárneho vzdelávania venujú. Z výskumných zistení vyplýva, že českí učitelia viac ako slovenskí a poľskí plánujú a projektujú vyučovanie, hodnotia žiakov a opravujú ich práce. Slovenskí učitelia najviac vysvetľujú nové učivo a poľskí najviac motivujú žiakov na vyučovaní a tvoria individuálne výchovno-vzdelávacie plány pre žiakov so špeciálnymi potrebami. Zistili sme tiež, že časová záťaž učiteľov primárneho vzdelávania v ich profesii v porovnaní s minulosťou rastie a okrem činností priamo alebo nepriamo súvisiacich s vyučovaním mnoho času venujú vzdelávaniu a sebavzdelávaniu v súvislosti s meniacimi sa spoločenskými a profesijnými podmienkami.
Transnational Corporate Social Responsibility: A Tri-Dimensional Approach to International CSR Research
Authors: Arthaud-Day Marne L.
Published: July 2012

Comparatively few studies have analyzed the social behavior of multinational corporations (MNCs) at a cross-national level. To address this gap in the literature, we propose a “transnational” model of corporate social responsibility (CSR) that permits identification of universal domains, yet incorporates the flexibility and adaptability demanded by international research. The model is tri-dimensional in that it juxtaposes: 1) Bartlett and Ghoshal’s (1998, 2000) typology of MNC strategies (multinational, global, “international,” and transnational); 2) the three conceptual domains of CSR (human rights, labor, and the environment) proposed by the UN Global Compact (Compact 2003); and 3) Zenisek’s (1979) description of three CSR perspectives (ideological, societal, and operational). The end result is a multidimensional typology that permits the organization and development of empirical CSR research in an international setting.
Business Ethics without Stakeholders
Authors: Heath Joseph
Published: July 2012

One of the most influential ideas in the field of business ethics has been the suggestion that ethical conduct in a business context should be analyzed in terms of a set of fiduciary obligations toward various “stakeholder” groups. Moral problems, according to this view, involve reconciling such obligations in cases where stakeholder groups have conflicting interests. The question posed in this paper is whether the stakeholder paradigm represents the most fruitful way of articulating the moral problems that arise in business. By way of contrast, I outline two other possible approaches to business ethics: one, a more minimal conception, anchored in the notion of a fiduciary obligation toward shareholders; and the other, a broader conception, focused on the concept of market failure. I then argue that the latter offers a more satisfactory framework for the articulation of the social responsibilities of business.
For Better or For Worse: Corporate Responsibility Beyond “Do No Harm”
Authors: Wettstein Florian
Published: July 2012

Do corporations have a duty to promote just institutions? Agreeing with Hsieh’s recent contribution, this article argues that they do. However, contrary to Hsieh, it holds that such a claim cannot be advanced convincingly only by reference to the negative duty to do no harm. Instead, such a duty necessarily must be grounded in positive obligation. In the search of a foundation for a positive duty for corporations to further just institutions, Stephen Kobrin’s notion of “private political authority” offers a promising connecting point. Political authority implies political responsibility; Political obligation, however, includes more than merely not doing any harm—it is essentially positive obligation. The implications of the new political responsibilities of multinational corporations may even go far beyond the particular duty to promote just institutions; they may be symptomatic for a much more profound shift from an individual to a collective age.
Extending the Horizon of Business Ethics: Restorative Justice and the Aftermath of Unethical Behavior
Authors: Goodstein Jerry , Butterfield Kenneth D.
Published: July 2012

We call for business ethics scholars to focus more attention on how individuals and organizations respond in the aftermath of unethical behavior. Insight into this issue is drawn from restorative justice, which moves beyond traditional approaches that emphasize retribution or rehabilitation to include restoring victims and other affected parties, reintegrating offenders, and facilitating moral repair in the workplace. We review relevant theoretical and empirical work in restorative justice and develop a conceptual model that highlights how this perspective can enhance theory and empirical research in business ethics. We specifically identify topic areas that we believe have particular promise for business ethics scholars to pursue. We close our paper by discussing implications of the restorative justice approach for practicing managers.
A comparative Suzuki reaction of aryl halides using a new dimeric orthopalladated complex under conventional and microwave irradiation conditions
Authors: Hajipour Abdol R. , Karami Kazem , Tavakoli Ghazal
Published: July 2012

The cross‐coupling reaction between phenylboronic acid and various types of aryl halides (Suzuki reaction) was carried out using a catalytic amount of a new phosphine‐based catalyst under microwave irradiation. The reaction conditions were optimized and results showed that, by application of this catalytic system, N‐methyl‐2‐pyrrolidone as the solvent and potassium carbonate as the base, reactions could be completed in a short reaction time with high to excellent yields. Copyright © 2012 John Wiley & Sons, Ltd.
Migrations and harvest rates of Arctic charr (Salvelinus alpinus) in a marine protected area
Authors: Morris Corey , Green John M.
Published: July 2012

Arctic charr are a particularly important species in Arctic and sub‐Arctic regions and face conservation challenges including human exploitation. Arctic charr migration pattern and harvest rate in the Gilbert Bay Marine Protected Area in southern Labrador, Canada were examined.

The marine movements of Arctic charr tagged with sonic transmitters were studied using an array of moored data logging ultrasonic receivers in Gilbert Bay and nearby Alexis Bay.

During subsistence gillnet fisheries conducted inside and outside the MPA 38% (8 of 21) of the tagged Arctic charr were recaptured. Surviving fish spent 7–8 weeks in the marine environment near coastal areas, often outside existing MPA boundaries. They then returned from these feeding areas to the Shinneys River in Gilbert Bay, a distance up to 25 km, during a 10 day period by directed and rapid movements.

This study provides the first information on the extent and timing of Arctic charr marine migrations in southern Labrador, and it identifies a potentially high rate of fishing mortality. The Gilbert Bay Marine Protected Area could provide more protection to the local Arctic charr population were MPA regulations applied to this species.

Copyright © Her Majesty the Queen in Right of Canada 2012
High Pressure Phase Equilibria of the Water‐Argon System
Authors: Wu G. , Heilig M. , Lentz H. , Franck E. U.
Published: July 2012

An experimental reinvestigation of the high‐temperature phase equilibria and critical curve of the water‐argon system was made for water mole fractionsxbetween 0.2 and 0.95 in the temperature range from 480 to 663 K and at pressures from 10 to 340 MPa. Molar volumes were measured at thepTx‐phase equilibrium surface. Contrary to the results of an earlier determination [3], the critical curve shows a temperature minimum at 637 K and 84 MPa and proceeds to 658 K at 261 MPa. Thus the curve belongs to the “type II”‐group. Phase equilibrium data are shown for pressures to 300 MPa. A calculation based on a rational equation of state confirms the critical curve.
Thermodynamic Properties of the Melt of the NaI — DyI3 System
Authors: Hilpert K. , Miller M. , Gerads H. , Saha B.
Published: July 2012

The vaporization of the phases of the NaI — DyI3 system present at a temperature of 1000 K, DyI3(s) + melt for 0 < xNaI < 0.53 and melt for 0.53 ≤ xNaI ≤ 1, has been investigated by Knudsen effusion mass spectrometry. The species NaI(g), (NaI)2(g), DyI3(g), NaDyI4(g), and Na2DyI5(g) were identified in the vapour and their partial pressures determined over the entire concentration range of the system. Chemical activities of NaI and DyI3 and excess chemical potentials of NaI were evaluated. The integral excess Gibbs energies of the melt were determined as negative and showed a minimum near the composition xNaI = 0.75 which may indicate the presence of short‐range ordering states of the composition 3NaI:DyI3 caused by the ionic complex [DyI6]3−. The partial pressures are discussed with respect to their significance for chemical vapour transport in metal halide lamps.
Thermodynamic Study of the Liquid and Solid Alloys of the Nickel‐Rich Part of the Al — Ni Phase Diagram Including the AlNi3 Phase
Authors: Hilpert K. , Miller M. , Gerads H. , Nickel H.
Published: July 2012

The vaporization of liquid and solid alloys of the Al — Ni system in the range xNi = 0.7 to 1 has been extensively investigated by the use of Knudsen effusion mass spectrometry in the temperature range between 1389 and 1734 K. 15 alloy samples of different compositions of the complete concentration range were studied in the course of 25 runs and their Al and Ni partial pressures determined. The vapour pressure measurements in the course of the individual runs were carried out over temperature ranges of up to about 300 K covering the solid and the liquid state for many of the alloys investigated. Chemical activities and chemical potentials for Al and Ni as well as Gibbs energies were evaluated at 1600 K for the solid and at 1728 K for the liquid state. Two independent methods were used for the determination of Ni activities of the solid alloys yielding consistent results. The large temperature range of the partial pressure measurement for the solid AlNi3 phase with xNi = 0.750 rendered possible the determination of a complete set of partial and integral thermodynamic functions (ΔG, ΔH, ΔS) for the formation of this phase. The values obtained are discussed. The partial and integral enthalpies of formation are compared with the enthalpies of dissociation of the gaseous species Ni2(g), Al2(g), and AlNi(g). The integral enthalpy of formation, obtained for the first time by vapour pressure measurements, agrees well with the results of a recent calorimetric study.
Thermophysical Properties of Alkali Metal Vapours, Part I — Theoretical Calculation of the Properties of Monatomic Systems
Authors: Nieto Castro C. A. De , Fareleira J. M. N. A. , Matias P. M. , Ramires M. L. V. , Pais A. A. C. Canelas , Varandas A. J. C.
Published: July 2012

Theoretical calculations of the second virial coefficients, self‐diffusion, viscosity and thermal conductivity of monatomic alkali metal vapours, lithium, sodium, potassium, cesium and rubidium are presented. The calculations have been carried out using reliable analytical two body interaction potential energy functions for the ground singlet 1Σ+g and the excited triplet 3Σ+g molecular states of the alkali dimers. The results are compared with previously calculated values. — The interpretation of experimental data on the thermophysical properties of alkali metal vapours is complicated by the formation of dimers. It follows that theoretical calculations for the monatomic species should thus provide an independent information on the zero density limits for the experimental properties. Full utilization of this principle is tried in Part II of this paper where an assessment of the available experimental data is attempted.
Extraction Kinetics of Europium(III) by Thenoyltrifluoroacetone and its Mixture with Triphenylphosphine Oxide in Chloroform from Perchlorate Medium
Authors: Daoud J. A. , Khalifa S. M. , Aly H. F.
Published: July 2012

The rate of extraction of Eu(III) from aqueous perchlorate solutions at constant ionic strength of 0.1 (H+, NaClO4) by thenoyltrifluoroacetone (HTTA) or its mixture with triphenylphosphine oxide (Ph3PO) in chloroform was studied using a stirred Lewis cell. The rate of extraction was measured at different [H+], [HTTA] and [Ph3PO]. For the chelate and adduct systems, the rate increased with the increase in [HTTA] and decreased with the increase in [H+]. The rate of extraction increased slightly with the increase in [Ph3PO]. The results were interpreted by a reaction mechanism where the 1 : 1 chelate formation steps in the aqueous phase are the rate‐determining steps. The rate constant kHL (HL = HTTA) and kL were found to be 9.20 ± 0.02 M−1 min−1 and 2.23 ± 0.04 · 103 M−1 min−1, respectively, for the extraction of Eu(III) by HTTA alone and 10.86 ± 0.03 M−1 min−1 and 1.41 ± 0.01 · 104 M−1 min−1 for the extraction by HTTA — Ph3PO mixture. Activation parameters were determined for both systems and discussed.
The Investigation of Near — Critical Mixtures by Means of the Nonlinear Dielectric Effect
Authors: Śliwińska‐Bartkowiak M.
Published: July 2012

Nonlinear dielectric effect (NDE) occurring in classical critical mixtures of o‐nitrotoluene with alkanes as well as mixtures m‐nitrotoluene with alkanes showing a formally similar NDE course was studied. The magnitude of the measured effect in critical mixtures is proportional to
equation image
where Φ ∼ 1/3. A similar dependence with the same exponent Φ was obtained for the other group of mixtures. — On the grounds of this analogy we conclude that a precritical effect occurs in the m‐nitrotoluene mixtures formally similar to the critical ones and we determine a hypothetical critical temperature for these mixtures.
Influence of Ni Deposits on the Catalytic CO Oxidation on Pt(110)
Authors: Ladas S. , Imbihl R.
Published: July 2012

The influence of Ni deposits in the submonolayer range on the activity of a Pt(110) surface in catalytic CO oxidation has been investigated in the 10−5 and 10−4 Torr range by means of reaction rate, LEED, AES and work function measurements. The presence of Ni on the surface led to an overall reduction of the CO2 production rate with the exception of the low temperature regime where an increase in the reaction rate could be observed for T ≦ 470 K. The increase in catalytic activity at low temperature could be traced back to a change in the CO adsorption properties caused by Ni which reduces the inhibitive effect of a CO adlayer on oxygen adsorption. With oxygen a ternary Pt/Ni/O phase could be observed characterized by a c(4 × 2) pattern in LEED. The reactivity of the oxygen in the ternary phase towards CO is at an intermediate level between the high reactivity of chemisorbed oxygen and the low reactivity of an oxide.
Sorption Kinetics of Xenon on MFI‐Type Zeolite Molecular Sieves
Authors: Bülow M. , Härtel U. , Müller U. , Unger K. K.
Published: July 2012

Kinetic uptake data for xenon adsorbed onto large and uniform silicalite‐I crystals are presented over a temperature range of 121 K to 296 K. — Adsorption isotherms and corrected diffusion coefficients derived from the uptake curves are given. The heat of adsorption and activation energy of diffusion were estimated from the plots of reciprocal temperature against the logarithm of equilibrium pressure and corrected diffusion coefficients, respectively. — While the corrected diffusion coefficient is independent of coverage for the higher temperatures, it decreases significantly at the lower temperatures investigated (<170 K) when the limiting adsorption capacity has been reached. — Comparing the sorption diffusion data with self‐diffusion coefficients obtained by NMR‐pulsed field gradient techniques, the room‐temperature mobility of xenon in silicalite‐I derived from sorption measurements is lowered by one order of magnitude. However, this result should not be considered necessarily as a discrepancy, due to uncertainties inherent in both techniques.
Potential Energy for the CO2‐NaCl(100) and the Lateral Adsorbate Interaction
Authors: Heidberg J. , Kampshoff E. , Schönekäs O. , Stein H. , Weiss H.
Published: July 2012

An empirical adsorption potentialVADof a single CO2molecule on the (100) face of NaCl is reported. The molecule‐surface interaction is calculated for different orientations of the adsorbed molecule. The lowest energy minimum is found for a molecule parallel to the surface above the cell center, having an energy of adsorption in good agreement with the measured value in the low coverage limit. Using the potential the vibrationalv2‐splitting is calculated for the different orientations of the molecule. — To determine the structure of the CO2‐monolayer on NaCl(100), intermolecular Coulomb and van der Waals terms are added to the molecule‐surface potential. Two basic overlayer structures, namely (2 × 2) and (2 x 1), are investigated and the potential minima determined under variation of the adsorbate configuration. In both cases we find an angle ϕ 90° between neighbouring molecules and a tilt angle ϑ of 30–40 between the CO2molecular axis and the NaCl(100) plane for adsorption sites above Na+. The deepest potential energy minimum for a (2 x 1) structure with 2D space group pg is found for CO2shifted by 0.07 Å from the center of the line between adjacent Na+and Cl−towards Cl−and ϕ = 85.6°,ϑ= 26.2°. According to our spectral line shape analysis and LEED measurements [12] the adsorbate has the (2 x 1) structure.
A Molecular Dynamics Study of the Interface between a Membrane and Water
Authors: Schlenkrich Michael , Nicklas Kai , Brickmann Jürgen , Bopp Philippe
Published: July 2012

The interface between a membrane, modelled by an ensemble of COO− functional groups with rotational and translational degrees of freedom, and liquid water, represented by the TIP4P model, is studied by molecular dynamics (MD) computer simulations. The structure of the bare membrane and of the membrane in the presence of water are studied by means of pair correlation functions. The influence of the membrane on the structure of the water is similarly discussed in terms of density profiles and distribution functions. Three ordered layers of water are found above the membrane, followed by a transition region to the bulk structure. Finally, the single molecule dynamics is examined. The translational self‐diffusion of the water is lowered by one order of magnitude in the vicinity of the membrane and remains anisotropic even above the layered water.
Hydrogen Bond Formation and Molecular Motion in Solutions of Aniline with Nitroxide Free Radicals
Authors: Stark U. , Müller‐Warmuth W.
Published: July 2012

1H NMR spin‐lattice relaxation rates and paramagnetic contact shifts have been measured at various temperatures and frequencies in solutions of aniline, aniline‐d2, and aniline‐d5 containing nitroxide free radicals. The data can be explained in terms of transient hydrogen bond formation between the amino protons and the NO group of the radical. Detailed information about the intermolecular transfer of electron spin density and the steric arrangement of the complex have been obtained. Molecular motions and interactions have been probed by relaxation measurements over a large frequency range between 100 kHz and 300 MHz. Relaxation is induced by dipolar interactions of the aniline protons with the unpaired electron spin and rotational tumbling of the associated system. The results are compared with other hydrogen‐bonded complexes of nitroxide radicals and proton donor solvent molecules.
Calculation of the Dielectric Constant of Water to 1000°C and Very High Pressures
Authors: Franck E. U. , Rosenzweig S. , Christoforakos M.
Published: July 2012

Measured data for the dielectric constant of water exist to 550°C and 5000 bar and to 400°C and 3000 bar (critical temperature: 374°C). The present calculations extend to 1000°C and a density of 1 g cm−3 (16000 bar). Results are given for densities between 0.1 and 1 g cm−3 and for temperatures to 1000°C. From 400 to 1000°C at densities of 0.1, 0.5 and 1.0 g cm−3 the dielectric constant varies from 2.04 to 1.50, from 10.45 to 4.69 and from 29.4 to 11.06 respectively. The calculation is based on a hard‐sphere with dipole moment molecular interaction model and an approximate equation of Patey et al. based on a linearized hypernetted chain procedure. The effective hard sphere diameter of 2.68 Å has been derived from fitting to existing PVT data to 1000°C by a suitable equation of state. The effective dipole moment of 2.33 D was obtained from fitting to existing experimental dielectric constant values to 550°C and high densities with the Patey equation. Analogous calculations of the dielectric constants of supercritical, dense HCl, NH3 and CH3F are presented.
The Glass Transition of Hard Spherical Colloids
Authors: Pusey P. N. , van Megen W.
Published: July 2012

When suspended in a liquid, hard spherical colloidal particles can show fluid, crytalline and glassy phases. A light scattering study of the dynamics of the metastable fluid and glassy phases is reported. Comparison is made with the predictions of mode‐coupling theories applied to the glass transition of simple atomic systems.
Particle Transport in Pores Bounded by Permeable Walls
Authors: Clark A. T. , Lal M. , Jones R. B.
Published: July 2012

Particle transport in pores bounded by a pair of parallel, semi‐infinite absorbing boundaries, ideally permeable to the suspending medium, is studied theoretically by solving the classical convective‐diffusive transport equation both for the first passage times and for the particle number versus time profiles. The initial transient appearing in the profiles is ascribed to the initial condition specifying the particle distribution in the pore before the onset of transport and absorption. At small convective flows, the post‐transient period in the profile is characterised by first‐order kinetics, but at large flow rates this period splits into two distinct regimes, one exhibiting zero‐order and the other first‐order kinetic behaviour. The rate constants obtained from the profiles are compared with those derived from the first passage times.
Response of (Poly)Atomic Fluids to Various Flows with Homogeneous Velocity Gradients
Authors: Ryckaert J. P.
Published: July 2012

In this paper a transient non‐equilibrium method based on the so called Sllod equations of motions is developed to study polyatomic fluids in flows with a homogeneous velocity gradient in space. Various flows like pure deformational, pure rotational or elongational flows can be imposed and accommodated with periodic boundary conditions in order to avoid surface effects. The method is illustrated on an atomic fluid, on liquid butane and on liquid chlorine subject respectively to a planar Couette flow, a purely deformational flow and a pure rotational flow.
Recollision Dynamics in the Hard Sphere Fluid
Authors: Vesely Franz J. , Evans Glenn T.
Published: July 2012

Given that two out of N hard spheres have collided at time t = 0, the probability of a recollision, as a function of time, was evaluated by molecular dynamics simulation. Using this conditional probability, certain time correlation functions of interest in the kinetic theory of the hard sphere fluid (and in theories of recombination processes) were computed. The initial values of all these tcf's could be reproduced independently as certain canonical averages. A decomposition of the recollision probability and the various tcf's in terms of first and second recollision functions is given. The first recollision functions in turn can be traced back to sequences of binary collisions involving 3, 4 or more hard spheres.
Non‐Markovian Effect on Diffusion‐Controlled Reactions
Authors: Dong W. , Baros F. , André J. C.
Published: July 2012

Recently we have carried out a molecular dynamics simulation of a model of diffusion‐controlled reactions in which the solvent is treated on an equal footing with reactants [8]. It is found that the rate of reactive encounter is larger at short times than that given by the Smoluchowski theory. In the present note it will be shown that the enhanced rate is due to a non‐Markovian effect. The theoretical approach for taking into account the non‐Markovian effect is a generalized diffusion equation, neglecting the mean force, with a time‐dependent diffusion coefficient which is related to the memory function of the velocity auto‐correlation function. By using the relaxation‐time approximation for the memory function, it can be shown that the motion of the mutual approach of the reactants is faster at short times than predicted by the classic Fick's law. It is this enhanced transport which is the physical origin of the enhanced reaction rate. Subjected to the absorbing boundary condition for reactivity, the generalized diffusion equation can still be solved analytically. The results have mathematical expressions as simple as those of the classic Smoluchowski theory.
Canonical Molecular Dynamics of Molecules with Internal Degrees of Freedom
Authors: Toxvaerd S. , Olsen O. H.
Published: July 2012

Canonical molecular dynamics simulations of molecules with internal degrees of freedom have been analysed by simulating alkanes at different temperatures and densities. The dynamics of a single thermostated butane molecule is not fully chaotic, even at high temperatures, and it tends to behave regular for large thermostat relaxation times. When the thermostat is applied to a fluid of butane molecules we only obtain a biased sampling for a low fluid density and only for thermostat relaxation times close to the fast intramolecular bond‐ and angle vibration times. The overall behaviour indicates that the anharmonic energy terms play a crucial role for the efficiency of the thermostat.
Dynamics of Liquids and Supercooled Water Studied by High Pressure Pulse NMR
Authors: Lüdemann H.‐D.
Published: July 2012

Data of the self diffusion coefficient for unpolar, polar, hydrogen bonded liquids and water are discussed and compared to existing molecular theories. — The liquids analyzed are a series of halomethanes (CF4, CF3H, CH3F), some monohydric alcohols (CH3OH, C2H5OH) and light and heavy water. They were studied at temperatures between their melting pressure curves and 450 K to pressures of 200 MPa. For methanol and water the data were extended into the supercooled range.
Multi‐Nuclear Relaxation Time Studies in Undercooled Aqueous Electrolytes
Authors: Lang E. W. , Fink W. , Radkowitsch H. , Girlich D.
Published: July 2012

The dynamic properties of water molecules coordinated to simple ions (alkali‐, alkali earth halides) in undercooled solutions have been investigated with NMR. Relaxation time studies at low temperatures provide details of molecular motions as well as certain features of the local arrangement in the coordination sphere of these ions.
Viscosities, Electric Conductivities and Self Diffusion Coefficients of Tetraalkylammonium‐tetraalkylborides
Authors: Weiden Norbert , Wittekopf Burghard , Weil Konrad G.
Published: July 2012

A number of salts of the type R3R'N+ · R3R'B− were prepared, with R, R' = aliphatic groups from methyl to octyl. Most of them are liquid at room temperature. The densities, electric conductivities, and viscosities of these salts were measured as functions of the temperature. Both transport properties correlate strongly with the molar volume, even with unsymmetric salts, where R and R' are different for anion and cation. — For a number of these salts, self diffusion coefficients of anions and cations could be determined by a spin‐echo NMR technique. For this purpose, the NMR signal of a proton from a methylene group adjacent to the central N or B atoms was used. In all investigated cases, the self diffusion coefficients of both constituents of a salt were identical. This finding excludes the applicability of concepts of individual contribution of ions to the transport processes in molten salts. — This is corroborated by the fact, that the Nernst‐Einstein equation does not quantitatively describe the relation between diffusion coefficients and conductivities: The experimental conductivities are in all cases smaller than those calculated from the self diffusion coefficients by use of the Nernst‐Einstein equation.
Ternary Diffusion in the Aqueous Solutions of MgCl2 + KCl, CdCl2 + KCl, ZnCl2 + KCl and Onsager's Reciprocity Relations
Authors: Spallek M. , Hertz H. G. , Funsch M. , Herrmann H. , Weingärtner H.
Published: July 2012

The diffusion coefficients D11, D12, D21, and D22 of the three systems MgCl2(1) + KCl(2) + H2O(3), CdCl2(1) + KCl(2) + H2O(3), and ZnCl2(1) + KCl(2) + H2O(3) have been measured at 25°C. The diaphragm cell method was applied. Diffusion coefficients for the following concentrations were obtained c1 = c2 = 0.25, 0.5, 0.75 M, and c1 = 0.25, 0.5, 0.75 M, c2 = 2c1 = 0.5, 1.0, 1.5 M. The Dij values which refer to the cell fixed system were transformed to the D'ij referring to the solvent fixed coordinate system. By the aid of thermodynamic data taken from the literature and from measurements with cells involving the solutions studied the derivatives of the partial chemical potentials δμi/δcj were determined. From all these data the phenomenological coefficients Ω'ij were calculated and we found the result that for MgCl2 + KCl + H2O Ω'12 = Ω'21 is valid whereas for the complex forming systems CdCl2 + KCl and ZnCl2 + KCl our study yielded phenomenological coefficients Ω'12 ≠ Ω'21.
Mass Transport Coefficients from Liquid Thermal Diffusion Columns
Authors: Ecenarro O. , Madariaga J. A. , Navarro J. L. , Santamaría C. M. , Carrión J. A. , Savirón J. M.
Published: July 2012

Experimental data on ordinary diffusion coefficient and thermal diffusion for binary liquid systems containing hexane, heptane, benzene, toluene and carbon tetrachloride are obtained from steady and non‐steady separation measurements in a thermal diffusion column. The data extraction uses a time evolution theory previously developed by the authors that accounts for density effects (the “forgotten effect”). The comparison of the diffusion data with those of the literature provides a powerful test of the derived thermal diffusion factors.
Pressure‐Temperature‐Dependence of Mass Density and Self‐Diffusion Coefficients in the Binary Liquid System n‐Hexane/Benzene
Authors: Brüsewitz Michael , Weiss Alarich
Published: July 2012

The self‐diffusion coefficients of n‐hexane and benzene have been measured in the temperature and pressure range 253.15 ≤ T/K ≤ 368.15; 1 ≤ P/bar ≤ 2000. The mol fraction x of benzene was varied over the range 0 ≤ x ≤ 1 in six steps. — The densities of the liquid mixtures and the pure substances were measured in the given Pressure (P)‐Temperature(T)‐range and the molar volumes were fitted to the Tait‐equation. — The P, T‐dependence of the self‐diffusion coefficients can be described in a phenomenological way by a polynomial. The self‐diffusion coefficients of benzene and n‐hexane in the liquid state vary at constant temperature by factors of 3.0 to 3.5 in the given P‐range. — The temperature dependence of the self‐diffusion coefficients is described by an Arrhenius‐type equation, which leads to activation energies EDa of both components in the binary system. EDa was studied in dependence of concentration and pressure. EDa increases for both compounds with increasing pressure and does not exceed 15 kJ mol−1. — EDa (benzene) depends stronger on the benzene‐concentration in the given P‐range than EDa (n‐hexane). — The free volume model for the transport properties in the liquid mixtures is applied to describe the self‐diffusion coefficients at constant molar volume Dv̄ = D(P,T).
Pressure Dependence of Resonant Intermolecular Vibrational Coupling etc.in Isotropic Raman Scattering of the v2 Mode of CH3I
Authors: Döge G. , Lindner D.
Published: July 2012

The pressure dependence of the isotopic dilution effect on the Raman band of the v2 mode of CH3I and CD3I has been investigated. In this way the resonant intermolecular vibrational coupling term has been separated from the other vibrational relaxation terms. It could be shown that the density dependence of this term is stronger then it is predicted from recent theories. The possible reasons for the discrepancy are discussed. The pressure dependence of a dynamical parameter τΩ is also obtained from the vibrational relaxation functions.
Strong Thermal Lens Induced by Laser Light in the Mixtures of Organic Liquids with Ferrocene
Authors: Kruk G. , Gburski Z.
Published: July 2012

Thermally induced changes in the refractive index of liquid benzene and ethyl alcohol, illuminated by the blue argon ion laser beam, were studied. The development of a thermal lens and strong increasing (factor of ten) of the defocusing angle of the incident laser beam. was observed for the liquids mixed with ferrocene.
Amplitude Ratios for Viscosity & Thermal Conductivity Anomalies Near a UCST
Authors: Maczek A. O. S. , Davies M. K. , Jayasuriya J. E. C.
Published: July 2012

Amplitudes of power laws which describe the viscosity of binary liquid mixtures in the close neighbourhood of a critical solution temperature were determined along the coexistence curve and along the critical isochore for a number of different systems. Dynamic renormalisation group theory predicts that the ratio of amplitudes along these two paths should be a universal constant, with a value of 0.950, for every binary system close to a critical point. If the amplitudes are determined by fitting the experimental viscosity data to a power law in which the critical exponent is treated as a disposable variable, the resulting ratios vary from about 0.94 to 0.97. If corrections for shear gradient dependence of the viscosity close to a critical point are made and the critical exponent is fixed at the value χλ = 0.040 predicted by dynamic renormalisation group theory, then all the systems considered show amplitude ratios which converge to 0.950 ± 0.001, in excellent agreement with theory. A similar analysis of results for the thermal conductivity anomaly detected in the system perfluoromethylcyclohexane + methylcyclohexane shows that, to within experimental error, the predicted amplitude ratio of 0.473 for thermal conductivity is compatible with the experimental data. Amplitude ratios for these transport properties appear indeed to be universal constants, as dynamic renormalisation group theory predicts.
Pressure‐jump Experiments for the Study of the Kinetics of Phase Separation in the Binary System Ethene/Hexane. I. Transient Light Scattering Measurements
Authors: Metz U. , Schneider G. M.
Published: July 2012

Measurements were performed with ethene/hexane mixtures at pressures up to 8 MPa and at temperatures from 293 to 323 K in order to study the process of demixing of a gas/liquid system. Supersaturation was achieved by a pressure jump technique that makes possible differential pressure jumps from 0.05 up to 1 MPa into metastable regions of the miscibility gap in less than 5 ms. ‐ The appearance of the new phase within the liquid mixture was observed by means of light scattering. Transient light scattering measurements at an angle of 90° were carried out in order to determine the kinetic limit of bubble growth following homogeneous nucleation along the phase boundary of the binary liquid with respect to a p(x) isotherm as well as to a T(x) isobar. It will be shown that the primary limitation of our light scattering measurements is the appearance of multiple scattering.
A Theoretical Study of the Time‐Dependence of Solvent Diffusion in a Polymer
Authors: Rudolph Franz , Peschel Gerhard
Published: July 2012

Based on experimental evidence in literature an attempt is made to theoretically derive an expression for the diffusion rate of a solvent in a polymer, a process by which the polymer can adopt a gellous state. In particular the movement of the solvent/gel interface is examined. With respect to the time dependence the solvent diffusion in polymers can be attributed to two cases

Proportional to t (Alfrey's Case I)

Proportional to √t (Alfrey's Case II)

Both cases are mathematically treated particularly with respect to the different time‐dependence of solvent diffusion.