Angewandte Chemie International Edition

Cover image for Vol. 49 Issue 28

June 28, 2010

Volume 49, Issue 28

Pages 4687–4837

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Cover Picture: Solid Solutions of Soft Porous Coordination Polymers: Fine-Tuning of Gas Adsorption Properties (Angew. Chem. Int. Ed. 28/2010) (page 4687)

      Tomohiro Fukushima, Satoshi Horike, Yasutaka Inubushi, Keiji Nakagawa, Yoshiki Kubota, Masaki Takata and Susumu Kitagawa

      Version of Record online: 20 MAY 2010 | DOI: 10.1002/anie.201002349

      Thumbnail image of graphical abstract

      The properties of porous frameworks can be modulated over the mesoscale domains in porous coordination polymers (PCPs). In their Communication on page 4820 ff., S. Horike, S. Kitagawa et al. demonstrate the synthesis of integrated crystals of two different types of flexible 2D layers. Changes in the composition of these so-called PCP solid solutions result in precise control of gas sorption isotherms and better performance than the parent compounds in the separation of a CO2/CH4 mixture.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Inside Cover: A Programmable DNA-Based Molecular Valve for Colloidal Mesoporous Silica (Angew. Chem. Int. Ed. 28/2010) (page 4688)

      Axel Schlossbauer, Simon Warncke, Philipp M. E. Gramlich, Johann Kecht, Antonio Manetto, Thomas Carell and Thomas Bein

      Version of Record online: 10 JUN 2010 | DOI: 10.1002/anie.201002607

      Thumbnail image of graphical abstract

      Controlled molecular valves for sealed nanocontainers are of interest for targeted drug delivery and self-healing polymers. In their Communication on page 4734 ff., T. Bein and co-workers present a DNA-based valve system for colloidal silica that has a precisely programmable opening temperature. This nanodevice consists of a mesoporous silica host, functionalization of the pore mouths with a DNA linker, and biotin–avidin coupling for valve closure.

  3. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
  4. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
  5. Author Profile

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Ivan Huc (page 4704)

      Version of Record online: 2 JUN 2010 | DOI: 10.1002/anie.201001747

      Thumbnail image of graphical abstract

      “My biggest motivation is curiosity. The secret of being a successful scientist is to constantly raise one's standards and creativity …” This and more about Ivan Huc can be found on page 4704.

  6. Book Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Reactive Intermediates. MS Investigations in Solution. Edited by Leonardo S. Santos. (pages 4705–4706)

      Dietmar Kuck

      Version of Record online: 11 JUN 2010 | DOI: 10.1002/anie.201002610

      Thumbnail image of graphical abstract

      Wiley-VCH, Weinheim 2010. 341 pp., hardcover € 129.00.—ISBN 978-3527323517

  7. Highlights

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Gallium(I) Chemistry

      At Last: A Stable Univalent Gallium Cation (pages 4708–4709)

      Rudolf J. Wehmschulte

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/anie.201001102

      Thumbnail image of graphical abstract

      The power of one: A stable gallium(I) cation has been prepared by a redox reaction (see scheme) and is stabilized by a weakly coordinating anion. The facile synthesis of the phosphine cation [(Ph3P)3Ga]+ is promising for the development of a rich coordination chemistry.

    2. Molecular Computers

      Data Processing on a Unimolecular Platform (pages 4710–4712)

      He Tian

      Version of Record online: 11 JUN 2010 | DOI: 10.1002/anie.200906834

      Thumbnail image of graphical abstract

      En route to bits and bytes: The integration of complex logic functions within individual molecules allows data processing at the molecular level, as demonstrated by recently reported molecular encoder and decoder devices. This research on decision-making molecules has great potential for future applications and more complex computing on a functional unimolecular platform.

  8. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. C[BOND]H Activation

      Carbene–Transition Metal Complexes Formed by Double C[BOND]H Bond Activation (pages 4714–4728)

      Helmut Werner

      Version of Record online: 28 MAY 2010 | DOI: 10.1002/anie.201000306

      Thumbnail image of graphical abstract

      Two at one blow: Fischer carbene–transition metal complexes are accessible by double α-C[BOND]H bond activation of alkane or cycloalkane derivatives containing an OR or NR2 functional group. Such complexes with M=Ir react with small molecules, such as CO2, CS2, and COS, and with azides (RN3) and N2O, by an atom- or group-transfer metathesis, which offers a novel possibility for C[BOND]H bond functionalization.

  9. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Single-Molecule Studies

      Pulling a Single Polymer Molecule off a Substrate Reveals the Binding Thermodynamics of Cosolutes (pages 4730–4733)

      Michael Geisler, Roland R. Netz and Thorsten Hugel

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/anie.200907098

      Thumbnail image of graphical abstract

      To bind or not to bind: Cosolutes modify, or even determine, the interactions between macromolecules and surfaces. A combination of single-molecule atomic force microscopy with thermodynamic modeling allows the extraction of the binding parameters of cosolutes onto a macromolecule in solution and also in its surface-adsorbed state.

    2. Programmable Host–Guest Systems

      A Programmable DNA-Based Molecular Valve for Colloidal Mesoporous Silica (pages 4734–4737)

      Axel Schlossbauer, Simon Warncke, Philipp M. E. Gramlich, Johann Kecht, Antonio Manetto, Thomas Carell and Thomas Bein

      Version of Record online: 10 JUN 2010 | DOI: 10.1002/anie.201000827

      Thumbnail image of graphical abstract

      Letting off steam: A temperature-controlled valve system permits the targeted release of guest fluorescein molecules from the pores of colloidal mesoporous silica particles. The pore-opening temperature is dependent on the length of double-stranded DNA linkers. Avidin proteins that are joined to the DNA by a biotin modification act as the molecular valve at the exits to the pores.

    3. Ferromagnetic Carbodiimide

      A Ferromagnetic Carbodiimide: Cr2(NCN)3 (pages 4738–4742)

      Xiaojuan Tang, Hongping Xiang, Xiaohui Liu, Manfred Speldrich and Richard Dronskowski

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/anie.201000387

      Thumbnail image of graphical abstract

      The same, but different: Chromium(III) carbodiimide (see structure), the first ferromagnetic carbodiimide, was synthesized from CrCl3 and ZnNCN and was characterized by X-ray diffraction. Despite being isostructural with antiferromagnetic Cr2O3, Cr2(NCN)3 adopts a ferromagnetic ground state as shown by SQUID measurements and correlated density-functional theory. At low temperatures, the phase shows a slightly larger magnetization than maghemite.

    4. Heterogeneous Catalysis

      Hydrogen Diffusion into Palladium Nanoparticles: Pivotal Promotion by Carbon (pages 4743–4746)

      Konstantin M. Neyman and Swetlana Schauermann

      Version of Record online: 20 MAY 2010 | DOI: 10.1002/anie.200904688

      Thumbnail image of graphical abstract

      The activation barrier for subsurface migration of surface hydrogen atoms on (111) facets of palladium nanoparticles drastically decreases or even vanishes in the presence of subsurface carbon atoms deposited nearby (see energy diagram). On regular Pd(111) surfaces, this promoting effect is essentially absent because of the hindered lateral mobility of the surface metal atoms.

    5. NMR Studies of RNA

      High-Resolution Studies of Uniformly 13C,15N-Labeled RNA by Solid-State NMR Spectroscopy (pages 4747–4750)

      Alexey V. Cherepanov, Clemens Glaubitz and Harald Schwalbe

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/anie.200906885

      Thumbnail image of graphical abstract

      Chilling out: Solid-state 13C NMR correlation spectroscopy was used to assign the signals of a uniformly labeled RNA hairpin in frozen aqueous solution. Conformational analysis shows that solutions of biologically relevant RNAs can freeze without significant changes in RNA structure and without critical loss of resolution and sensitivity in NMR experiments.

    6. Sulfur Heterocycles

      Synthesis of Dibenzothiophenes and Related Classes of Heterocycles by Using Functionalized Dithiocarbamates (pages 4751–4754)

      Marcel Kienle, Andreas Unsinn and Paul Knochel

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/anie.201001025

      Thumbnail image of graphical abstract

      A round trip: Readily available dithiocarbamates can undergo ring closure to give functionalized sulfur heterocycles (see scheme). These heteroaromatic compounds can be further functionalized by directed alumination and subsequently trapped with various electrophiles.

    7. Chemical Defense

      Novel Acetylenic Oxylipins from the Moss Dicranum scoparium with Antifeeding Activity against Herbivorous Slugs (pages 4755–4758)

      Martin Rempt and Georg Pohnert

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/anie.201000825

      Thumbnail image of graphical abstract

      A slug stopper: The defensive properties of oxylipins from the moss Dicranum scoparium are far more active than required to fend off herbivory by a common slug. The precursor-guided structure elucidation of seven novel and several known unusual oxylipins was supported by chemometric data mining.

    8. Stable Carbenes

      Crystalline 1H-1,2,3-Triazol-5-ylidenes: New Stable Mesoionic Carbenes (MICs) (pages 4759–4762)

      Gregorio Guisado-Barrios, Jean Bouffard, Bruno Donnadieu and Guy Bertrand

      Version of Record online: 27 MAY 2010 | DOI: 10.1002/anie.201001864

      Thumbnail image of graphical abstract

      Click makes MICs: A short modular synthesis allows the preparation of novel stable heterocycles that feature a lone pair of electrons on a carbon center. The donor properties of these mesoionic compounds are greater than those of classical N-heterocyclic carbenes; they are accessible by deprotonation of the corresponding conjugate acids using comparatively mild bases.

    9. Asymmetric Catalysis

      Highly Enantioselective Insertion of Carbenoids into N[BOND]H Bonds Catalyzed by Copper(I) Complexes of Binol Derivatives (pages 4763–4766)

      Zongrui Hou, Jun Wang, Peng He, Jing Wang, Bo Qin, Xiaohua Liu, Lili Lin and Xiaoming Feng

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/anie.201001686

      Thumbnail image of graphical abstract

      Secondary amines do it too! Catalytic asymmetric insertion of α-diazoesters in the N[BOND]H bond of differently substituted amines has been successfully achieved (see scheme; M.S.=molecular sieves). For a wide substrate scope, excellent enantioselectivities (up to 98 % ee) and high yields (up to 99 %) were obtained under mild reaction conditions.

    10. Structural Transformations

      Single-Crystal-to-Single-Crystal Transformations of Two Three-Dimensional Coordination Polymers through Regioselective [2+2] Photodimerization Reactions (pages 4767–4770)

      Dong Liu, Zhi-Gang Ren, Hong-Xi Li, Jian-Ping Lang, Ni-Ya Li and Brendan F. Abrahams

      Version of Record online: 20 MAY 2010 | DOI: 10.1002/anie.201001551

      Thumbnail image of graphical abstract

      The crystal method: Single-crystal-to-single-crystal (SCSC) transformations of two 3D coordination polymers, {[Zn43-OH)2(5-sipa)2(1,4-bpeb)2]4 H2O}n (see picture; C pale blue, N dark blue, H green) and an analogous cadmium species, gave rise to corresponding linked 3D coordination polymers through photochemical [2+2] cycloaddition reactions.

    11. Clinical Analytics

      Paper-Based ELISA (pages 4771–4774)

      Chao-Min Cheng, Andres W. Martinez, Jinlong Gong, Charles R. Mace, Scott T. Phillips, Emanuel Carrilho, Katherine A. Mirica and George M. Whitesides

      Version of Record online: 28 MAY 2010 | DOI: 10.1002/anie.201001005

      Thumbnail image of graphical abstract

      Paper works: Paper-based indirect ELISA (see picture) has been demonstrated through the detection of rabbit IgG and the HIV-1 envelope antigen gp41. This technique combines the sensitivity and specificity of ELISA with the low cost and ease-of-use of paper-based platforms.

    12. Structure Elucidation

      Unprecedented Stylissazoles A–C from Stylissa carteri: Another Dimension for Marine Pyrrole-2-aminoimidazole Metabolite Diversity (pages 4775–4779)

      Kirti Patel, Rémi Laville, Marie-Thérèse Martin, Supriya Tilvi, Céline Moriou, Jean-François Gallard, Ludmila Ermolenko, Cécile Debitus and Ali Al-Mourabit

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/anie.201000444

      Thumbnail image of graphical abstract

      No cramping this “styl”: The three title compounds, dimeric pyrrole-2-aminoimidazole alkaloids, were isolated from the marine sponge Stylissa carteri collected in the Solomon Islands. The isolated compounds are exclusively N[BOND]C-bonded “dimers”, which indicates a different mode of dimerization and adds another dimension to the molecular diversity of pyrrole-2-aminoimidazole alkaloids.

    13. Molecular Logic

      Electrically Addressable Multistate Volatile Memory with Flip-Flop and Flip-Flap-Flop Logic Circuits on a Solid Support (pages 4780–4783)

      Graham de Ruiter, Leila Motiei, Joyanta Choudhury, Noa Oded and Milko E. van der Boom

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/anie.201000785

      Thumbnail image of graphical abstract

      Flip-flopping away: Multivalue random access memory can be achieved using electrically addressable Os2+-based multilayers. The controllable optical properties of the multilayers allow the construction of memory devices that are able to store up to five different states that depend on the given electrical inputs (see picture). The functions of the devices can be represented by sequential logic circuits that are equivalent to flip-flop and flip-flap-flop devices.

    14. Chlorinated Fullerenes

      Chlorination of C86 to C84Cl32 with Nonclassical Heptagon-Containing Fullerene Cage Formed by Cage Shrinkage (pages 4784–4787)

      Ilya N. Ioffe, Chuanbao Chen, Shangfeng Yang, Lev N. Sidorov, Erhard Kemnitz and Sergey I. Troyanov

      Version of Record online: 25 MAY 2010 | DOI: 10.1002/anie.201001082

      Thumbnail image of graphical abstract

      Shrunken fullerene: An unexpected heptagon-containing C84 fullerene cage was found in C84Cl32, which was formed, in addition to C86(16)Cl28, by chlorination of C86(16) with VCl4. Comparison of the structures of C84Cl32 (see picture; C gray, Cl green; red bonds highlight the heptagon) and C86(16)Cl28 and theoretical calculations suggest that cage shrinkage occurs by removal of a C2 unit from the corranulene-like fragment of the C86(16) cage.

    15. E[BOND]E Triple Bonds

      Cleavage of the Sn[BOND]Sn Multiple Bond in a Distannyne by Cyclooctatetraene: Formation of the π-Bound Inverse Sandwich Complex [(Ar′Sn)2223-cot)] (pages 4788–4790)

      Owen T. Summerscales, Xinping Wang and Philip P. Power

      Version of Record online: 21 MAY 2010 | DOI: 10.1002/anie.201001276

      Thumbnail image of graphical abstract

      The adventures of tin-tin: The activation of cyclooctatetraene by a distannyne results in complete Sn[TRIPLE BOND]Sn bond cleavage and formation of a π-bound planar aromatic C8H8 ring in an inverse sandwich complex (see scheme; Ar′=C6H3-2,6-(C6H3-2,6-iPr2)2)

    16. Metal–Organic Frameworks

      Dynamics of Benzene Rings in MIL-53(Cr) and MIL-47(V) Frameworks Studied by 2H NMR Spectroscopy (pages 4791–4794)

      Daniil I. Kolokolov, Hervé Jobic, Alexander G. Stepanov, Vincent Guillerm, Thomas Devic, Christian Serre and Gérard Férey

      Version of Record online: 28 MAY 2010 | DOI: 10.1002/anie.201001238

      Thumbnail image of graphical abstract

      Rotational dynamics of benzene rings in the flexible MIL-53 and rigid MIL-47 frameworks was investigated by 2H NMR spectroscopy. In both cases, 180° flips are observed, and the flipping rate is higher in MIL-53. To simulate experimental spectra (left), consideration of the quadrupolar interaction alone is not sufficient (middle); the paramagnetic effect must also be taken into account (right).

    17. Graphene-Based Nanosheets

      Graphene-Based Nanosheets with a Sandwich Structure (pages 4795–4799)

      Shubin Yang, Xinliang Feng, Long Wang, Kun Tang, Joachim Maier and Klaus Müllen

      Version of Record online: 28 MAY 2010 | DOI: 10.1002/anie.201001634

      Thumbnail image of graphical abstract

      A bottom-up approach was employed for the large-scale production of 2D graphene-based nanosheets which have a sandwich structure and consist of silica, carbon, and metal or metal oxide (see picture). These nanosheets exhibit many unique features such as a large aspect ratio, high surface area, and high monodispersibility, which render them suitable for broad application in catalysis, sensors, and batteries.

    18. Cerebral Glucose Detection

      Colorimetric Detection of Glucose in Rat Brain Using Gold Nanoparticles (pages 4800–4804)

      Ying Jiang, Hong Zhao, Yuqing Lin, Ningning Zhu, Yurong Ma and Lanqun Mao

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/anie.201001057

      Thumbnail image of graphical abstract

      A gold-based assay: By taking advantage of the unique optical properties of gold nanoparticles (AuNPs) and the cascade reactions of glucose, a simple but effective method has been successfully developed for the direct colorimetric visualization of glucose in the rat brain. GOD=glucose oxidase.

    19. DNA Unfolding

      Real-Time Atomistic Description of DNA Unfolding (pages 4805–4808)

      Alberto Perez and Modesto Orozco

      Version of Record online: 17 MAY 2010 | DOI: 10.1002/anie.201000593

      Thumbnail image of graphical abstract

      An unfolding story: Simulations exceeding the microsecond timescale and the introduction of a co-solvent were used to characterize the pathways of the unfolding of a short DNA duplex. Two main pathways are detected involving different substrates. Once unfolding is reached the DNA adopts compact structures different from a random-coil distribution (see picture).

    20. Conformation Analysis

      The Tubulin-Bound Structure of the Antimitotic Drug Tubulysin (pages 4809–4812)

      Karel Kubicek, S. Kaspar Grimm, Julien Orts, Florenz Sasse and Teresa Carlomagno

      Version of Record online: 21 MAY 2010 | DOI: 10.1002/anie.200906828

      Thumbnail image of graphical abstract

      Bound to be active: The solution structure of tubulin-bound tubulysin A is determined from transferred NOE data (see picture; blue N, red O, yellow S, green C), and this bioactive conformation is compared to the unbound conformation. The binding site on tubulin is examined on the basis of the interligand NOEs observed between epothilone A and tubulysin A in the presence of tubulin.

    21. Electrocatalysis

      Tailoring the Selectivity for Electrocatalytic Oxygen Evolution on Ruthenium Oxides by Zinc Substitution (pages 4813–4815)

      V. Petrykin, K. Macounova, O. A. Shlyakhtin and Petr Krtil

      Version of Record online: 31 MAY 2010 | DOI: 10.1002/anie.200907128

      Thumbnail image of graphical abstract

      Controlling gas emissions: Versatile control of the selectivity of an oxide electrocatalyst in the oxygen- and chlorine-evolution reactions was demonstrated by Zn substitution in RuO2 (see picture: O red, Cl green, Zn blue, Ru white). The incorporation of Zn into the rutile structure alters the cation sequence along the [001] direction and modifies the structure of the active sites for both gas-evolution processes.

    22. Encapsulation and Reactivity

      Molecular Recognition of a Transition State (pages 4816–4819)

      Xiaoguang Bao, Stephen Rieth, Sandra Stojanović, Christopher M. Hadad and Jovica D. Badjić

      Version of Record online: 28 MAY 2010 | DOI: 10.1002/anie.201000656

      Thumbnail image of graphical abstract

      An inside job: The conformational interconversion of cyclohexane occurs at a higher rate in the interior of gated molecular baskets (see picture) than in bulk free solvent or a vacuum. The acceleration results from more favorable noncovalent bonding, and hence stabilization of the transition state, of the encapsulated compound.

    23. Coordination Polymers

      Solid Solutions of Soft Porous Coordination Polymers: Fine-Tuning of Gas Adsorption Properties (pages 4820–4824)

      Tomohiro Fukushima, Satoshi Horike, Yasutaka Inubushi, Keiji Nakagawa, Yoshiki Kubota, Masaki Takata and Susumu Kitagawa

      Version of Record online: 20 MAY 2010 | DOI: 10.1002/anie.201000989

      Thumbnail image of graphical abstract

      My flexible friend: Separation of a CO2/CH4 mixture was optimized by varying the composition of solid solutions of interdigitated 2D frameworks comprising two different isophthalate ligands (see picture). The characteristics of the solid solutions were dependent on the ligand ratio, which influenced the inherent flexibility and therefore the adsorption properties of the frameworks.

    24. Self-Organization

      Dissipative Self-Assembly of a Molecular Gelator by Using a Chemical Fuel (pages 4825–4828)

      Job Boekhoven, Aurelie M. Brizard, Krishna N. K. Kowlgi, Ger J. M. Koper, Rienk Eelkema and Jan H. van Esch

      Version of Record online: 28 MAY 2010 | DOI: 10.1002/anie.201001511

      Thumbnail image of graphical abstract

      Fueling the future: A fibrillar network (red fibers, see figure) is formed from an activated building block (red), which is obtained from a synthetic gelator (blue) in a dissipative self-assembly process that is fueled by an alkylating agent. When the available energy is depleted, the system reverts to its thermodynamic equilibrium, that is, an isotropic solution.

    25. Organic Metals

      A Two-Dimensional Organic Metal Based on Fullerene (pages 4829–4832)

      Dmitri V. Konarev, Salavat S. Khasanov, Akihiro Otsuka, Mitsuhiko Maesato, Gunzi Saito and Rimma N. Lyubovskaya

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/anie.201001463

      Thumbnail image of graphical abstract

      The first fullerene organic metal: (MDABCO+)⋅TPC⋅(C60.−), which has two-dimensional layers with a honeycomb arrangement of C60.− (see picture), is a fascinating example of a material composed of only light elements (C, H, N); it adopts a metallic state down to 1.9 K.

  10. Preview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. You have free access to this content

SEARCH

SEARCH BY CITATION