ChemPhysChem

Cover image for Vol. 6 Issue 8

August 12, 2005

Volume 6, Issue 8

Pages 1429–1666

    1. Cover Picture: Structural Colors in Nature: The Role of Regularity and Irregularity in the Structure (ChemPhysChem 8/2005) (page 1429)

      Shuichi Kinoshita and Shinya Yoshioka

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200590016

      The cover picture shows the mechanism of structural color in the famous Morpho butterflies ranging over Central and South America. Their wings are covered extensively with iridescent scales, on which a lot of ridges bristle with regular projections at both sides. In their Review on page 1442 Kinoshita et al. demonstrate that these regular structures assist the selective reflection of blue light through interference, while their irregular heights give the diffusive light through diffraction. Thus the cooperation of regularity and irregularity generates wavelength-selective, highly reflective, and spatially diffusive light in the blue region.

    2. Graphical Abstract: ChemPhysChem 8/2005 (pages 1431–1441)

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200590017

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      Intramolecular Electron Transfer in Nitrite Reductases (page 1440)

      Scot Wherland, Ole Farver and Israel Pecht

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200590018

    4. Structural Colors in Nature: The Role of Regularity and Irregularity in the Structure (pages 1442–1459)

      Shuichi Kinoshita and Shinya Yoshioka

      Article first published online: 14 JUL 2005 | DOI: 10.1002/cphc.200500007

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      Natural coloring: Colors in nature can have a physical origin. Structural color, or iridescence, originates from optical processes such as thin-film interference, multilayer interference, diffraction grating effects, photonic crystals, or light scattering. This Review examines the hierarchy of these processes, particularly in relation to the structures found in some butterflies, beetles, and birds (see picture). Applications of structural colors in industry are also discussed.

    5. Biocompatible and Biodegradable Polymer Nanofibers Displaying Superparamagnetic Properties (pages 1461–1465)

      Song Ting Tan, Joachim H. Wendorff, Clemens Pietzonka, Zhi Hong Jia and Gui Qing Wang

      Article first published online: 11 JUL 2005 | DOI: 10.1002/cphc.200500167

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      Nanofiber drug carriers: Polymer nanofibers containing both magnetite (Fe3O4) nanoparticles and a fluorescent albumin were fabricated by the electrospinning technique. The hybrid nanofibers display superparamagnetism and green luminescence, which can be observed by fluorescence optical microscopy (see picture), and they slowly release the albumin component in aqueous medium.

    6. Formation and Decomposition of Surface Ethoxy Species on Acidic Zeolite Y (pages 1467–1469)

      Wei Wang, Jian Jiao, Yijiao Jiang, Siddharth S. Ray and Michael Hunger

      Article first published online: 6 JUL 2005 | DOI: 10.1002/cphc.200500262

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      Observing a catalyst at work: The first 13C cross-polarization (CP)/magic-angle spinning (MAS) NMR spectroscopic evidence for the existence of surface ethoxy species on acidic zeolite Y is reported. In situ 13C CP/MAS NMR–UV/Vis spectroscopy was used to investigate the further decomposition of surface ethoxy species on zeolite H-Y (see picture) to hydrocarbons at elevated reaction temperatures.

    7. A Novel CeO2/ZnO Catalyst for Hydrogen Production from the Partial Oxidation of Methanol (pages 1470–1472)

      Liuye Mo, Xiaoming Zheng and Chuin-Tih Yeh

      Article first published online: 13 JUL 2005 | DOI: 10.1002/cphc.200500119

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      Clean energy: Ce20Zn was found to be a very good catalyst for the selective and effective production of hydrogen from the partial oxidation of methanol at a mild temperature of 200 °C. The figure shows the effect of Ce loading on the catalytic performance of different CexZn catalysts (CMeOH=methanol conversion; SH2=hydrogen selectivity; SCO=CO selectivity).

    8. Linear Configuration of the Spins of a Stable Trinitroxide Radical Based on a Ternary Helical Peptide (pages 1472–1475)

      Elena Sartori, Carlo Corvaja, Simona Oancea, Fernando Formaggio, Marco Crisma and Claudio Toniolo

      Article first published online: 6 JUL 2005 | DOI: 10.1002/cphc.200500139

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      Peptide secondary structure: An octapeptide with three TOAC (2,2,6,6-tetramethyl-1-oxyl-4-amino-4-carboxylic acid) residues forms a 310-helix in the crystal state. The three nitroxide radicals are placed in a linear configuration (see picture). As determined by electron paramagnetic resonance (EPR) spectroscopy, this secondary structure is preserved in solvents of low polarity, while in polar solvents the regularity of the 310-helix is disrupted.

    9. Manipulation of Surface Wettability between Superhydrophobicity and Superhydrophilicity on Copper Films (pages 1475–1478)

      Shutao Wang, Lin Feng, Huan Liu, Taolei Sun, Xi Zhang, Lei Jiang and Daoben Zhu

      Article first published online: 11 JUL 2005 | DOI: 10.1002/cphc.200500204

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      Wet, wetter, wettest: The surface wettability of copper films can be controlled between superhydrophobicity and superhydrophilicity by micro- and nanoscale hierarchical structures and self-assembled monolayers of alkanoic acids. The picture shows the shapes of water droplets on films prepared with different acids and the contact angle as a function of acid chain length.

    10. High-Density Data Recording in an Optoelectrical Dual-Responsive Thin Film (pages 1478–1482)

      Guiyuan Jiang, Yanlin Song, Yongqiang Wen, Wenfang Yuan, Huimeng Wu, Zhi Yang, Andong Xia, Min Feng, Shixuan Du, Hongjun Gao, Lei Jiang and Daoben Zhu

      Article first published online: 6 JUL 2005 | DOI: 10.1002/cphc.200500184

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      On the record: Five-layer optical information storage based on two-photon excitation and nanoscale electrical data recording by scanning tunneling microscopy have been demonstrated in an optoelectrical dual-responsive thin film (see picture). The recording mechanism is ascribed to charge transfer and the conformational change is induced by light and an electric field. The data can be optically and/or electrically recorded and read.

    11. The Structure and Conformations of 2-Thiophenecarboxaldehyde Obtained from Partially Averaged Dipolar Couplings (pages 1483–1491)

      Maria Concistrè, Giuseppina De Luca, Marcello Longeri, Giuseppe Pileio and James W. Emsley

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200500190

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      Assigning by colour: The conformational equilibrium of 2-thiophenecarboxaldehyde in a fluid phase was investigated by analysing the 1H NMR spectra of samples dissolved in a liquid crystalline solvent, and the results were compared with density functional calculations. A colour-code-based graphical procedure helps in simplifying the spectral analysis (see figure).

    12. A Theoretical Description of Elastic Pillar Substrates in Biophysical Experiments (pages 1492–1498)

      Camilla Mohrdieck, Alexander Wanner, Wouter Roos, Alexander Roth, Erich Sackmann, Joachim P. Spatz and Eduard Arzt

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200500109

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      Pillars of strength? Elastic pillar substrates are widely used to sense traction forces of cells (see graphic) and biopolymeric networks suspended on them. The authors develop an analytical description to evaluate these forces which provides a guideline for the construction as well as for the quantitative evaluation of experiments involving pillar substrates as micromechanical sensors.

    13. Phase Diagram of Electrostricted H2O at Surfaces of Electrodes at 273–373 K: Electric Critical Point of Water (pages 1499–1509)

      Irena Danielewicz-Ferchmin and A. Ryszard Ferchmin

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200500106

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      The phase diagram of water at a charged electrode with (Π, σ) isotherms (see picture; Π=electrostriction pressure, σ=surface charge density) shows a region of coexistence of H2O phase A, with strongly oriented dipoles, and phase B, with weakly oriented dipoles. The electric critical point C is at the top. Qualitatively, phase A is analogous to the condensed phase, while phase B is reminiscent of the gas phase in a real gas (inverted) phase diagram with (p, −V) isotherms.

    14. Identification of Two Isomers from an Organic Mixture by Double-Stimulated-Echo NMR and Construction of the DOSY Spectra by the Regularized Resolvent Transform Method (pages 1510–1513)

      Pierre Thureau, André Thévand, Bernard Ancian, Philippe Escavabaja, Geoffrey S. Armstrong and Vladimir A. Mandelshtam

      Article first published online: 20 JUL 2005 | DOI: 10.1002/cphc.200500192

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      Shape sorter: Two structural isomers with different shapes but identical mass fragmentation patterns can be characterized by DOSY-NMR spectroscopy, with data processing by the regularized resolvent transform method (iRRT; see picture). The ellipsoidal isomer (green) diffuses more slowly than the quasi-spherical one (red), in agreement with the Stokes–Einstein theory.

    15. Ab initio Studies of ClOx Reactions: Prediction of the Rate Constants of ClO+NO2 for the Forward and Reverse Processes (pages 1514–1521)

      R. S. Zhu and M. C. Lin

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200400448

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      Radical findings: The complete potential-energy surface (PES) for the forward and reverse reactions of the ClO radical with NO2 has been constructed at the CCSD(T)/6-311+G(3df)//B3LYP/6-311+G(3df) level of theory in conjunction with variational Rice–Ramsperger–Kassel–Marcus (RRKM) calculations (see schematic diagram of the PES). Rate constants for both the forward and reverse reactions, and for the related ClONO2 decomposition, are predicted.

    16. CO Oxidation on Pt-Modified Rh(111) Electrodes (pages 1522–1529)

      T. H. M. Housmans, J. M. Feliu, R. Gómez and M. T. M. Koper

      Article first published online: 20 JUL 2005 | DOI: 10.1002/cphc.200400658

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      CO electro-oxidation: The catalytic effect of Pt monolayers deposited on Rh(111) electrodes on CO oxidation has been investigated by STM characterization, cyclic voltammetry, and chronoamperometry. The improved CO tolerance of the Pt-monolayer system is explained based on changes in the surface morphology and electronic structure (see graphic).

    17. Experimental and Theoretical Investigation of the Room-Temperature Photoluminescence of Amorphized Pb(Zr,Ti)O3 (pages 1530–1536)

      Emmanuelle Orhan, Fenelon M. Pontes, Edson R. Leite, Paulo S. Pizani, José A. Varela and Elson Longo

      Article first published online: 20 JUL 2005 | DOI: 10.1002/cphc.200500030

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      Room-temperature photoluminescence (PL) of lead zirconate titanate (PZT) is investigated by four physical methods during physical processing (see figure). Theoretical studies performed using three different approaches explain the appearance of this PL.

    18. Kinetic and DFT Studies on the Ag/TiO2-Photocatalyzed Selective Reduction of Nitrobenzene to Aniline (pages 1537–1543)

      Hiroaki Tada, Tetsuji Ishida, Ayako Takao, Seishiro Ito, Sudip Mukhopadhyay, Tomoki Akita, Koji Tanaka and Hisayoshi Kobayashi

      Article first published online: 6 JUL 2005 | DOI: 10.1002/cphc.200500031

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      Ag nanoparticles increase catalytic power: The high photocatalytic activity and selectivity for the reduction of nitrobenzene to aniline is rendered to inactive TiO2 in the presence of methanol by loading a small amount of Ag nanoparticles. The kinetic experiments and DFT calculations reveal the essential reaction mechanism. The picture shows a high-resolution transmission electron micrograph of the Ag/TiO2 system.

    19. Modeling of X-ray-Induced Refractive Index Changes in Poly(methyl methacrylate) (pages 1544–1553)

      Birk Andreas, Ingo Breunig and Karsten Buse

      Article first published online: 8 JUL 2005 | DOI: 10.1002/cphc.200500068

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      Polymer index: The refractive index (n) of bulk poly(methyl methacrylate) is modified by X-ray exposure. An increase or decrease in n is observed in dependence on the absorbed dose. The simultaneous radiation-induced changes in n and thickness are measured interferometrically (see picture; arrows represent synchrotron light). A model is proposed which describes quantitatively the observed refractive index changes.

    20. Van der Waals Interactions in Aromatic Systems: Structure and Energetics of Dimers and Trimers of Pyridine (pages 1554–1558)

      Manuel Piacenza and Stefan Grimme

      Article first published online: 13 JUL 2005 | DOI: 10.1002/cphc.200500100

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      Aromatic van der Waals complexes have quite flat potential-energy hypersurfaces according to detailed dispersion-corrected density functional theory (DFT-D) optimizations of pyridine dimers and trimers. Four stacked, two T-shaped, and one H-bridged dimers, as well as two stacked trimers, were investigated with DFT-D and ab initio methods. The picture shows the most stable, stacked dimer.

    21. Gas-Phase Structure of N,N-Dimethylglycine (pages 1559–1566)

      Alberto Lesarri, Emilio J. Cocinero, Juan C. López and José L. Alonso

      Article first published online: 6 JUL 2005 | DOI: 10.1002/cphc.200500103

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      Three conformers ofN,N-dimethylglycine (see picture) in the neutral form were observed in a supersonic jet by combination of laser ablation and molecular-beam Fourier transform microwave spectroscopy. The most stable conformer (left) may be stabilised by a bifurcated methyl-to-carbonyl weak intramolecular hydrogen bond. Ab initio MP2/6-311++G(d,p) predictions of the spectroscopic parameters including nuclear quadrupole coupling constants aided in analysing the spectra.

    22. Pressure Dependence in the Methyl Vinyl Ketone+OH and Methacrolein+OH Oxidation Reactions: An Electronic Structure Study (pages 1567–1573)

      Montserrat Ochando-Pardo, Ignacio Nebot-Gil, Àngels González-Lafont and José M. Lluch

      Article first published online: 18 JUL 2005 | DOI: 10.1002/cphc.200500115

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      Pressure group: The attack of the OH radical on methyl vinyl ketone and methacrolein, the major oxidation by-products of isoprene, can lead to H abstraction and OH addition reactions (see picture; grey: C, blue: H, red: O atoms). High-level electronic structure calculations help to explain the observed pressure dependence of these tropospheric processes in terms of a balance between the possible pathways.

    23. Paradoxical Solvent Effects on the Absorption and Emission Spectra of Amino-Substituted Perylene Monoimides (pages 1574–1580)

      Peter D. Zoon and Albert M. Brouwer

      Article first published online: 14 JUL 2005 | DOI: 10.1002/cphc.200500127

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      Solvatochromic shifts in absorption and emission spectra are commonly analyzed using models which assume solvent-independent dipole moments in the ground and excited states. This approach fails for pyrrolidino-perylenedicarboximide 5PI (blue circles in the figure), which shows solvatochromic shifts in absorption and emission, but a solvent-independent Stokes shift.

    24. In Situ and Online Monitoring of Hydrodynamic Flow Profiles in Microfluidic Channels Based upon Microelectrochemistry: Concept, Theory, and Validation (pages 1581–1589)

      Christian Amatore, Alexander Oleinick, Oleksiy V. Klymenko and Irina Svir

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200500129

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      Microfluidic flow: A method that allows the reconstruction of any experimental flow profile occurring in a microfluidic flow channel (see figure) is proposed and its validity established. The method is fundamentally rooted in the extraction of the diffusion pattern probed by a redox mediator whose flux is controlled by an array of microelectrodes.

    25. Femtosecond S3[RIGHTWARDS ARROW]S1 Conversion and Structural Reorganisation of trans-3-Phenylprop-2-enaldehyde and Derivatives in Solution (pages 1590–1599)

      J. L. Pérez Lustres, Vadim M. Farztdinov and Sergey A. Kovalenko

      Article first published online: 6 JUL 2005 | DOI: 10.1002/cphc.200400518

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      Ultrafast dynamics: Femtosecond broadband transient absorption of trans-3-phenylprop-2-enal and derivatives was measured after S3[LEFTWARDS ARROW]S0 excitation in solution (see picture). The transient spectra exhibit two time components. Semiempirical calculations help to assign the fast component to S3[LEFTWARDS ARROW]S1 conversion and the picosecond decay to structural reorganisation, which serves as source for trans and cis isomers in the ground state.

    26. Ion Binding to Bilayers of the Iridescent Phase in Aqueous Tetradecyldimethylaminoxid Studied by Mass Spectrometry (pages 1600–1605)

      Anna Jakubowska

      Article first published online: 18 JUL 2005 | DOI: 10.1002/cphc.200400541

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      Specific ion effects (Hofmeister effects) in tetradecyldimethylaminoxid (C14DMAO) iridescent solutions are investigated by mass spectrometry. The results show that electrospray ionisation mass spectrometry is a powerful tool for observing the competition between ions in binding to interfaces (see picture).

    27. Modeling of the Adsorption of Organic Compounds on Polymeric Nanofiltration Membranes in Solutions Containing Two Compounds (pages 1606–1612)

      Leen Braeken, Katleen Boussu, Bart Van der Bruggen and Carlo Vandecasteele

      Article first published online: 8 JUL 2005 | DOI: 10.1002/cphc.200400624

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      Nanofiltration is one of the most promising techniques for producing high-quality drinking water. However, the performance of the polymeric membranes used in this process can be seriously affected by the presence of organic adsorbats. It is shown that the simple competitive adsorption model (SCAM) predicts the real adsorption behavior quite well (see figure; q90=mass of benzylidene acetone adsorbed on an N30F membrane, C90=equilibrium concentration).

    28. A Colloidal Au Monolayer Modulates the Conformation and Orientation of a Protein at the Electrode/Solution Interface (pages 1613–1621)

      Xiue Jiang, Lei Zhang, Junguang Jiang, Xiaohu Qu, Erkang Wang and Shaojun Dong

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200400652

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      Gold-colloid-modified electrodes were investigated with regard to the orientation and conformation of adsorbed cytochrome c (cyt c) at the electrode/solution interface. The Au monolayer, formed by binding colloidal Au to a preformed organic self-assembled monolayer (SAM), increases the electronic coupling between the SAM and cyt c. A possible model for the adsorption orientation of cyt c at the electrode/solution interface is proposed (see picture).

    29. Structural Heterogeneity in DNA: Temperature Dependence of 2-Aminopurine Fluorescence in Dinucleotides (pages 1622–1627)

      Oscar J. G. Somsen, Linda B. Keukens, M. Niels de Keijzer, Arie van Hoek and Herbert van Amerongen

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200400648

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      Fluorescent base analogues provide an excellent opportunity to study interactions between neighboring bases in DNA. The time-resolved fluorescence of a dinucleotide is most easily explained with three conformational states and a transient opening of the excited state (see figure).

    30. Ultrafast Fluorescence Depolarisation in the Yellow Fluorescent Protein due to Its Dimerisation (pages 1628–1632)

      Gregor Jung, Yingzhong Ma, Bradley S. Prall and Graham R. Fleming

      Article first published online: 18 JUL 2005 | DOI: 10.1002/cphc.200400653

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      Not crystals but dimers are the exclusive states of aggregation of autofluorescent proteins from Aequorea victoria in solution at high concentration according to a study by transient absorption spectroscopy with sub-100 fs time resolution. The close contact of two protein barrels (see schematic diagram) leads to ultrafast energy migration (2.2 ps) accompanied by a partial loss of polarisation.

    31. Kinetics of the Initial Steps of G Protein-Coupled Receptor-Mediated Cellular Signaling Revealed by Single-Molecule Imaging (pages 1633–1640)

      Yoriko Lill, Karen L. Martinez, Markus A. Lill, Bruno H. Meyer, Horst Vogel and Bert Hecht

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200500111

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      Membrane receptors are very important for cellular signaling. In this context, G protein-coupled receptors (GPCR) play a prominent role. The authors report on an in vivo single-molecule study of the signaling kinetics of GPCR performed using the neurokinin 1 receptor (NK1R) as a representative member (see figure).

    32. Molecular Dynamics Simulation of Water Near Nanostructured Hydrophobic Surfaces: Interfacial Energies (pages 1641–1649)

      Sandeep Pal, Danilo Roccatano, Horst Weiss, Harald Keller and Florian Müller-Plathe

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200500074

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      Water repelled by corrugation: The picture shows the water-density distribution in the vicinity of a hole (a) and a protrusion (b) on the surface of a hydrophobic crystal. Molecular dynamics simulations have been performed to study the structural properties of water. The interfacial free energy of the water/hydrophobic crystal interface is analysed.

    33. Photophysical Characterization of Light-Emitting Poly(indenofluorene)s (pages 1650–1660)

      Panagiotis E. Keivanidis, Josemon Jacob, Luke Oldridge, Prashant Sonar, Benjamin Carbonnier, Stanislav Baluschev, Andrew C. Grimsdale, Klaus Müllen and Gerhard Wegner

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200400634

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      Blue-light-emitting devices: Two different synthetic routes, used for the preparation of three different blue-light electroluminescent poly(indenofluorene) (PIF) derivatives, are compared in terms of photophysical material properties. Results of controlled doping experiments are discussed for a model host (arylated PIF)–guest (indenofluorene ketone) system. The identified photoluminescence (PL) quenchning rate kq becomes comparable to the PL rate of the host kobs. at a guest loading level of 0.3 wt % (see picture).

    34. You have free access to this content
      Preview: ChemPhysChem 8/2005 (page 1666)

      Article first published online: 4 AUG 2005 | DOI: 10.1002/cphc.200590019

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