ChemPhysChem

Cover image for Vol. 11 Issue 16

November 15, 2010

Volume 11, Issue 16

Pages 3369–3551

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
    9. Articles
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    1. Cover Picture: MRI Thermometry Based on Encapsulated Hyperpolarized Xenon (ChemPhysChem 16/2010) (page 3369)

      Franz Schilling, Dr. Leif Schröder, Krishnan K. Palaniappan, Sina Zapf, Prof. David E. Wemmer and Prof. Alexander Pines

      Article first published online: 5 NOV 2010 | DOI: 10.1002/cphc.201090079

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      The cover picture shows a new magnetic resonance imaging (MRI) method using encapsulated hyperpolarized xenon to map temperature, described on p. 3529 by F. Schilling, A. Pines et al. This method allows unprecedented absolute temperature accuracy of 0.1 °C at low and ultralow sensor concentrations. The method is based on the temperature-dependent chemical shift of hyperpolarized xenon in a cryptophane-A cage (shown in the upper left corner). This shift can be detected by MRI and is linear with a slope of 0.29 ppm °C−1 as can be seen in the graph. Three distinct NMR signals appear in a xenon NMR spectrum (see figure at the bottom): the signal of xenon dissolved in water at around 190 ppm, the xenon-in-cage signal at around 60 ppm, and the peak of gaseous xenon at 0 ppm. The xenon-in-cage peak is used for direct temperature mapping by relating its chemical shift to temperature based on the linear gauge curve. This way, dynamic heating procedures can be observed as for example the build-up of a temperature gradient (see figure in the upper right corner). Thermometry based on hyperpolarized xenon sensors improves the accuracy of currently available MRI thermometry methods, potentially giving rise to biomedical applications that could include monitoring of thermotherapy in cancer treatment or the detection of hot arteriosclerotic plaques.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
    9. Articles
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    1. Inside Cover: Oxidative Dehydrogenation of Propane over a VO2-Exchanged MCM-22 Zeolite: A DFT Study (ChemPhysChem 16/2010) (page 3370)

      Sippakorn Wannakao, Dr. Bundet Boekfa, Dr. Pipat Khongpracha, Prof. Dr. Michael Probst and Prof. Dr. Jumras Limtrakul

      Article first published online: 5 NOV 2010 | DOI: 10.1002/cphc.201090080

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      Determination of mechanisms of industrially important reactions over porous materials is challenging. The adsorption and mechanism of the oxidative dehydrogenation of propane over a zeolite are investigated by J. Limtrakul et al. on p. 3432 using DFT.

  3. Graphical Abstract

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
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    1. Graphical Abstract: ChemPhysChem 16/2010 (pages 3371–3379)

      Article first published online: 5 NOV 2010 | DOI: 10.1002/cphc.201090081

  4. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
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  5. Essay

    1. Top of page
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    5. News
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    1. Many Faces of Entropy or Bayesian Statistical Mechanics (pages 3387–3394)

      Dr. Evgeni B. Starikov 

      Article first published online: 23 SEP 2010 | DOI: 10.1002/cphc.201000583

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      Undeservedly forgotten: George A. Linhart's publications some 80–90 years ago in which—unlike Einstein, Debye, Planck and Nernst—he succeeded in deriving a simple, but ultimately general mathematical formula for heat capacity versus temperature from fundamental thermodynamic principles, using what we would nowadays dub a “Bayesian approach to probability”, became totally forgotten, although they represent a valid and fresh standpoint on thermodynamics and statistical physics. The aim of this essay is to restore the memory of these great works.

  6. Highlights

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
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    1. Entangled Photons from a Light-Emitting Diode (pages 3395–3397)

      Prof. Dr. Oliver Benson

      Article first published online: 4 OCT 2010 | DOI: 10.1002/cphc.201000711

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      Current sources for entangled photon pairs rely mostly on spontaneous parametric down-conversion in nonlinear optical crystals. Such sources have the drawback of producing pairs randomly and require powerful optical pump lasers. C. L. Salter et al. have now developed a new source that generates entangled photon pairs on demand under electrical excitation. The device is similar to a classical light-emitting diode (see picture). Its robust and integrated design makes it suitable for applications in quantum information processing.

    2. Light on Molecular Machines (pages 3398–3403)

      Prof. Alberto Credi, Prof. Margherita Venturi and Prof. Vincenzo Balzani

      Article first published online: 16 AUG 2010 | DOI: 10.1002/cphc.201000520

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      On the move: Nanoscale machines function according to mechanisms which are fundamentally different from those of their macroscopic counterparts. Recent spectroscopic experiments with sufficiently high resolution in time and space reveal new details on the intimate operation of molecular shuttles powered by light and are highlighted herein.

  7. Communications

    1. Top of page
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    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
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    1. Charge Transport Induced by Formation of a Single Covalent Bond (pages 3405–3407)

      Dr. Tomoaki Nishino

      Article first published online: 21 SEP 2010 | DOI: 10.1002/cphc.201000686

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      Quantum leap: A molecular tip of a scanning tunneling microcope is utilized to detect conductance change induced by in situ covalent bond formation between single molecules. Thiol groups of sample and tip molecules form a disulfide linkage, which bridges the gap between the gold tip and the substrate (picture, top). Current jumps take place by electron transport through the molecular bridge, and this electron transport is successfully quantified (picture, bottom).

    2. Simultaneous Optical and Electrical Recording of Single Molecule Bonding to Single Channel Proteins (pages 3408–3411)

      Dr. Toru Ide

      Article first published online: 9 SEP 2010 | DOI: 10.1002/cphc.201000560

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      Two birds with one stone: A method is described for simultaneous optical and electrical recordings of single ion-channel proteins by combining the artificial bilayer technique and single-molecule imaging with a total internal reflection fluorescence microscope. Using this apparatus, interactions between single DNA molecules and single alpha-hemolysin channels are measured (see picture).

    3. Electroluminescence from Individual Pentacene Nanocrystals (pages 3412–3416)

      Alexander Kabakchiev, Dr. Klaus Kuhnke, Theresa Lutz and Prof. Dr. Klaus Kern

      Article first published online: 28 OCT 2010 | DOI: 10.1002/cphc.201000531

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      Twinkle, twinkle: Electroluminescence is induced and characterized from individual nanoscale pentacene crystals by means of scanning tunneling microscopy (see picture). Conditions, limits and mechanism of light generation from the organic nanocrystals are investigated and discussed.

    4. An Autocatalytic Cycle Model of Asymmetric Amplification and Mirror-Symmetry Breaking in the Soai Reaction (pages 3417–3419)

      Dr. Jean-Claude Micheau, José-Manuel Cruz, Dr. Christophe Coudret and Dr. Thomas Buhse

      Article first published online: 4 OCT 2010 | DOI: 10.1002/cphc.201000526

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      Do it yourself: An autocatalytic cycle network is introduced to accurately reproduce the unprecedented features of the Soai reaction such as huge asymmetric autoamplification and spontaneous mirror-symmetry breaking. In contrast to previous attempts, which were based on formal kinetics, the present mechanism involves interconnected realistic structures including dimers, trimers and tetramers and resembles stereoselective and template-directed self-replication (see picture).

    5. Coherent Excitation and Relaxation of the Coupled S1/S2 Electronic States of Naphthalene (pages 3420–3423)

      Raúl Montero, Dr. Álvaro Peralta Conde, Dr. Asier Longarte and Prof. Fernando Castaño

      Article first published online: 24 SEP 2010 | DOI: 10.1002/cphc.201000718

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      Femtosecond time-resolved ionization reveals the coherent nature of the electronic excitation and relaxation of the S1 (Lb) and S2 (La) excited states of naphthalene (see picture). The authors describe two different types of coherent behavior: adiabatic evolution, resulting in the transient population of the S2 state excited out of resonance, and electronic recurrences, observed in the relaxation of this resonantly populated state as a consequence of the strong S2/S1 nonadiabatic coupling.

  8. Articles

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
    9. Articles
    10. Preview
    1. Temperature-Dependent Prediction of the Liquid Entropy of Ionic Liquids (pages 3425–3431)

      Dr. Ulrich Preiss, Dr. Vladimir N. Emel'yanenko, Prof. Dr. Sergey P. Verevkin, Dr. Daniel Himmel, Dr. Yauheni U. Paulechka and Prof. Dr. Ingo Krossing

      Article first published online: 22 OCT 2010 | DOI: 10.1002/cphc.201000614

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      Ionic Liquid Entropies: The temperature-dependent liquid entropy of ionic liquids (ILs) is predicted to within 2 % of the experimental value. The influence of ion pairing versus the use of single ions on the accuracy of the prediction is investigated. The first parameterization of the standard entropy specifically for ILs in the context of volume-based thermodynamics is given (see picture).

    2. Oxidative Dehydrogenation of Propane over a VO2-Exchanged MCM-22 Zeolite: A DFT Study (pages 3432–3438)

      Sippakorn Wannakao, Dr. Bundet Boekfa, Dr. Pipat Khongpracha, Prof. Dr. Michael Probst and Prof. Dr. Jumras Limtrakul

      Article first published online: 25 OCT 2010 | DOI: 10.1002/cphc.201000586

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      Propene production: The adsorption and the mechanism of the oxidative dehydrogenation of propane over VO2-exchanged MCM-22 (see picture) are investigated by DFT calculations using the M06-L functional, which takes into account dispersion contributions to the energy.

    3. Interaction of Aromatic Derivatives with Single-Walled Carbon Nanotubes (pages 3439–3446)

      Wei-Chun Hung, Dr. Gracy Elias and Prof. Dr. Chien M. Wai

      Article first published online: 27 SEP 2010 | DOI: 10.1002/cphc.201000570

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      Pass the electron, please: Fluorescence of semiconducting single-walled carbon nanotubes (SWNTs) normally exhibits diameter-dependent oxidative quenching behaviour upon titration with hydrogen peroxide. This behaviour can be substantially changed to become an almost diameter-independent quenching phenomenon in the presence of electron-withdrawing nitroaromatic compounds (see picture).

    4. Defeating Radiation Damping and Magnetic Field Inhomogeneity with Spatially Encoded Noise (pages 3447–3455)

      Prof. Carl A. Michal

      Article first published online: 6 OCT 2010 | DOI: 10.1002/cphc.201000527

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      Adding noise to improve resolution:1H NMR spectra of D-glucose in an inhomogeneous magnetic field are acquired (see figure) with ordinary single pulse excitation (above) and with spatial noise encoding (below). In addition to providing high-resolution spectra in inhomogeneous fields, this excitation strategy also eliminates the effects of radiation damping.

    5. Organosilica Spheres Covalently Functionalized with Diphenylanthracene and Viologen Units (pages 3456–3464)

      Dr. Mercedes Álvaro, Giorgia Bizzoca, Dr. Belén Ferrer, Prof. Dr. Hermenegildo García, Maykel de Miguel and Dr. Laura Teruel

      Article first published online: 28 OCT 2010 | DOI: 10.1002/cphc.201000494

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      Photochemical response: Long-lived organic radical cations incorporated in functionalized silica spheres (viologen, VIO@SPH, see figure) introduce a photochemical response in the silica spheres. The photoinduced electron acceptor/donor characteristics of the organic components prevail and can be used in optical applications.

    6. Complexation of Phenol and Thiophenol by Amine N-Oxides: Isothermal Titration Calorimetry and ab Initio Calculations (pages 3465–3473)

      Ir. Ruud Cuypers, Dr. Sukumaran Murali, Dr. Antonius T. M. Marcelis, Prof. Dr. Ernst J. R. Sudhölter and Prof. Dr. Han Zuilhof

      Article first published online: 22 OCT 2010 | DOI: 10.1002/cphc.201000482

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      Extraction of (thio)phenol in industrial processes requires detailed information on the nature of the H bonds between the extractants (here a series of amine N-oxides) and (thio)phenol. This is provided by a combination of high-level quantum chemical calculations and calorimetry. The picture shows raw data (top) together with peak-integration data and fitted curve (bottom) for the calorimetric titration of phenol with dimethyldodecylamine N-oxide.

    7. Paramagnetic Relaxation Enhancements in Acetate and Its Fluorine Derivatives Interacting with Gd3+: Complex Formation, Structure, and Transmetallation (pages 3474–3484)

      Dr. Célia S. Bonnet and Dr. Pascal H. Fries

      Article first published online: 26 OCT 2010 | DOI: 10.1002/cphc.201000448

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      A simple relaxation measurement:1H and 19F relaxation times of acetate and its fluorinated derivatives give access to structural parameters and thermodynamic stability constants of the complexes formed with Gd3+ (see figure). Transmetallation of Gd3+ by endogenous Zn2+ is also determined accurately with this easy method.

    8. 3He Impurities in Nearly Frictionless Transport of Solid 4He at Low Temperatures (pages 3485–3490)

      Prof. Kwang-Hua W. Chu

      Article first published online: 16 SEP 2010 | DOI: 10.1002/cphc.201000401

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      Superfluidity: Glassy matter, when subjected to high shear rates, exhibits shear thinning, that is, the viscosity diminishes with increasing shear rate. One possible outcome for the almost vanishing viscosity is a nearly frictionless transport, which is possible in solid 4He due to the presence of minute concentrations of 3He (see figure).

    9. CdS-Encapsulated TiO2 Nanotube Arrays Lidded with ZnO Nanorod Layers and Their Photoelectrocatalytic Applications (pages 3491–3498)

      Dr. Ya-nan Zhang, Prof. Guohua Zhao, Yanzhu Lei, Dr. Peiqiang Li, Mingfang Li, Yuning Jin and Baoying Lv

      Article first published online: 17 SEP 2010 | DOI: 10.1002/cphc.201000371

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      A novel structure composed of TiO2 nanotubes (NTs)/CdS/ZnO nanorods (NRs) is obtained by encapsulating CdS nanoparticles (NPs) into the hollow shell of a TiO2 NT/ZnO NR composite. The new material resembles “empty bottles with a lid” and shows broad-wave response, superior photoelectrocatalytic activity, and long-term stability for methyl orange oxidation in the UV/Vis region.

    10. Glycine Dimers: Structure, Stability, and Medium Effects (pages 3499–3504)

      Dr. Pascale Friant-Michel and Dr. Manuel F. Ruiz-López

      Article first published online: 24 SEP 2010 | DOI: 10.1002/cphc.201000354

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      Two to tango: The calculated structures of glycine dimers are stable in the gas phase, in hydrophobic solvents, and in aqueous solution. Moreover, the dimerization process appears to be exergonic in all these media. In water, zwitterion–zwitterion structures predominate (see picture). It is shown that dimers might be abundant in supersaturated aqueous solutions.

    11. Theoretical Investigation of the Interaction between Carbon Monoxide and Carbon Nanotubes with Single-Vacancy Defects (pages 3505–3510)

      Dr. Bo Xiao, Dr. Jing-xiang Zhao, Prof. Yi-hong Ding and Prof. Chia-chung Sun

      Article first published online: 30 SEP 2010 | DOI: 10.1002/cphc.201000325

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      Healing defects: Computational results demonstrate the efficient adsorption of a CO molecule on single-vacancy defects (see picture) in carbon nanotubes. The subsequent reaction with a second CO molecule forms CO2 that leaves the perfect tube surface. This mechanism indicates a dual role of CO in carbon nanotube synthesis—carbon source and defect healing.

    12. Emergence of Supramolecular Chirality by Flows (pages 3511–3516)

      Dr. Oriol Arteaga, Dr. Adolf Canillas, Dr. Joaquim Crusats, Dr. Zoubir El-Hachemi, Prof. Joan Llorens, Eduardo Sacristan and Prof. Dr. Josep M. Ribo

      Article first published online: 26 OCT 2010 | DOI: 10.1002/cphc.201000658

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      In a stirring flask the descending and ascending flows have different chiral signs and the emerging signal depends on the weighting of these two flows. Circular dichroism (CD) and linear dichroism (LD) in the stirred cuvettes do not correlate, which agrees with the bending/floding of the nano-objects by the effect of flows (see picture; cw: clockwise, ccw: counterclockwise).

    13. Fluoride Sensing by Catechol-Based π-Electron Systems (pages 3517–3521)

      Dr. Byeong-Kwan An, Dr. Xin Wang, Prof. Paul L. Burn and Prof. Paul Meredith

      Article first published online: 25 OCT 2010 | DOI: 10.1002/cphc.201000582

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      Selectivity: Catechol-based sensors detect fluoride selectively via fluorescence or optical absorption. The sensitivity of detection is dependent on the chromophore length and fluoride can be sensed over the concentration range 1.7–200 μm (see figure). The catechol dye can detect fluoride in aqueous solution when adsorbed onto a solid support.

    14. [11]Anthrahelicene on InSb(001) c(8×2): A Low-Temperature Scanning Probe Microscopy Study (pages 3522–3528)

      Dr. Jakub S. Prauzner-Bechcicki, Szymon Godlewski, Dr. Janusz Budzioch, Grzegorz Goryl, Lukasz Walczak, Dr. Petr Sehnal, Dr. Irena G. Stará, Dr. Ivo Starý, Dr. Francisco Ample, Prof. Christian Joachim and Prof. Marek Szymonski

      Article first published online: 24 SEP 2010 | DOI: 10.1002/cphc.201000547

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      Molecular bridge: Adsorption and self-assembly of [11]anthrahelicene molecules on an InSb(001) surface is studied with low-temperature scanning probe microscopy (see picture). Molecules adsorb with the helical axis almost perpendicular to the substrate, decorating atomic step edges at lower coverage. At higher coverage, islands with a quasi-hexagonal ordering are formed. Interference between tunneling through the molecular layer and directly through space is reported.

    15. MRI Thermometry Based on Encapsulated Hyperpolarized Xenon (pages 3529–3533)

      Franz Schilling, Dr. Leif Schröder, Krishnan K. Palaniappan, Sina Zapf, Prof. David E. Wemmer and Prof. Alexander Pines

      Article first published online: 6 SEP 2010 | DOI: 10.1002/cphc.201000507

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      A new approach to MRI thermometry using encapsulated hyperpolarized xenon is demonstrated. The method is based on the temperature dependent chemical shift of hyperpolarized xenon in a cryptophane-A cage (see figure). Noninvasive, accurate and spatially resolved temperature measurement in the human body is a desirable technology for many biomedical applications.

    16. α-Chymotrypsin-Catalyzed Reaction Confined in Block-Copolymer Vesicles (pages 3534–3540)

      Dr. Qi Chen, Kristin G. Rausch, Prof. Dr. Holger Schönherr and Prof. Dr. G. Julius Vancso

      Article first published online: 25 OCT 2010 | DOI: 10.1002/cphc.201000429

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      Nanoscale reactors: α-Chymotrypsin is confined into nanoscale block copolymer vesicles and the reactivity of the encapsulated enzymes in differently sized vesicles is monitored (see picture). The enzyme possesses a higher catalytic activity when it is loaded into smaller vesicles, which is attributed to the volume confinement effect of the vesicles.

    17. Versatile Functionalization of Nanoelectrodes by Oligonucleotides via Pyrrole Electrochemistry (pages 3541–3546)

      Dr. Emeline Descamps, Dr. Khoa Nguyen, Dr. Christelle Bouchain-Gautier, Dr. Arianna Filoramo, Dr. Laurence Goux-Capes, Dr. Marcello Goffman, Dr. Jean-Philippe Bourgoin, Dr. Pascal Mailley and Dr. Thierry Livache

      Article first published online: 22 OCT 2010 | DOI: 10.1002/cphc.201000101

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      The selective and efficient functionalization of individual nanoelectrodes of an array with distinct DNA scaffolds is described based on the localized electropolymerization of polypyrrole–oligonucleotide nanofilms. The results open up a new route to the versatile bio-assembly of nanocomponents based on DNA scaffolds and enable high-density integration in a biotechnology context.

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    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Essay
    7. Highlights
    8. Communications
    9. Articles
    10. Preview
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      Preview: ChemPhysChem 17/2010 (page 3551)

      Article first published online: 5 NOV 2010 | DOI: 10.1002/cphc.201090083

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