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  1. AU="Kirsch, Harald"
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  1. Book ; Online ; Thesis: Chemical reactions on surfaces

    Kirsch, Harald

    a SFG study

    2014  

    Title variant Chemische Reaktionen auf Oberflächen
    Author's details Harald Kirsch
    Language English
    Size Online-Ressource, Ill., graph. Darst.
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Freie Univ., Diss.--Berlin, 2014
    Database Former special subject collection: coastal and deep sea fishing

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  2. Article: The use of geo-information tools and products in participatory land use planning (PLUP) in rural Cambodia

    Kirsch, Harald

    Pacific news : Nachrichten, Mitteilungen, Hintergründe aus dem Pazifischen Raum Vol. 23 , p. 23-26

    2005  Volume 23, Page(s) 23–26

    Language English
    Publisher APSA
    Publishing place Göttingen
    Document type Article
    ZDB-ID 2011646-9
    Database Former special subject collection: coastal and deep sea fishing

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  3. Article: CH2 Stabilized at Steps on Ru(0001) by Coadsorbates

    Kirsch, Harald / Zhao Xunhua / Ren Zefeng / Levchenko SergeyV / Campen R. Kramer

    The Journal of Physical Chemistry C. 2016 Nov. 03, v. 120, no. 43

    2016  

    Abstract: Insight into the controls of stability of one-carbon moieties adsorbed on transition-metal surfaces is important in the optimization of such industrially important processes such as the Fischer–Tropsch (FT) synthesis, that is, (2n+1)H2+nCO⇄metalCnH(2n+2)+ ...

    Abstract Insight into the controls of stability of one-carbon moieties adsorbed on transition-metal surfaces is important in the optimization of such industrially important processes such as the Fischer–Tropsch (FT) synthesis, that is, (2n+1)H2+nCO⇄metalCnH(2n+2)+nH2O. While the broad steps of FT synthesis are clear, CO dissociatively adsorbs on steps on transition-metal surfaces, this carbon is hydrogenated, one-carbon groups are coupled, and the resulting larger molecule desorbs, a deeper description of the mechanism has proven challenging. In particular, while experiment and calculation of barriers for coupling reactions suggest that step-bound CH₂ should be the chain growth one-carbon species, calculations of CH₂/CH relative stability at low surface coverages suggest CH₂ dissociation is too rapid to allow such a pathway and thus CH is the likely candidate. In this study, we characterize the dissociation of CH₂ adsorbed at steps on the Ru(0001) surface in ultrahigh vacuum using laser-based technique vibrational sum frequency (VSF) spectroscopy and electronic structure calculation. Experimentally, we find the barrier for CH₂ dissociation to be 0.47 eV, 3× larger than the calculated barrier for dissociation of an isolated CH₂ on a terrace on the Ru(0001) surface. However, both our experiment and real application steps are likely saturated by adsorbed carbon species. For such a system, we show that both the barrier for CH₂ dissociation and that for the diffusion of CH away from the steps each increase 2–3×. This result highlights the large influence of coadsorbates on step-bound one-carbon moieties and provides a means of reconciling previous apparently contradictory results on the FT synthesis.
    Keywords carbon ; dissociation ; lasers ; moieties ; spectroscopy
    Language English
    Dates of publication 2016-1103
    Size p. 24724-24733.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021%2Facs.jpcc.6b07088
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: Characterization of water dissociation on α-Al2O3(11[combining macron]02): theory and experiment.

    Wirth, Jonas / Kirsch, Harald / Wlosczyk, Sebastian / Tong, Yujin / Saalfrank, Peter / Campen, R Kramer

    Physical chemistry chemical physics : PCCP

    2016  Volume 18, Issue 22, Page(s) 14822–14832

    Abstract: The interaction of water with α-alumina (i.e. α-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water ... ...

    Abstract The interaction of water with α-alumina (i.e. α-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water interaction with α-Al2O3 surfaces other than the (0001) are extremely limited. Here we characterize the interaction of water (D2O) with a well defined α-Al2O3(11[combining macron]02) surface in UHV both experimentally, using temperature programmed desorption and surface-specific vibrational spectroscopy, and theoretically, using periodic-slab density functional theory calculations. This combined approach makes it possible to demonstrate that water adsorption occurs only at a single well defined surface site (the so-called 1-4 configuration) and that at this site the barrier between the molecularly and dissociatively adsorbed forms is very low: 0.06 eV. A subset of OD stretch vibrations are parallel to this dissociation coordinate, and thus would be expected to be shifted to low frequencies relative to an uncoupled harmonic oscillator. To quantify this effect we solve the vibrational Schrödinger equation along the dissociation coordinate and find fundamental frequencies red-shifted by more than 1500 cm(-1). Within the context of this model, at moderate temperatures, we further find that some fraction of surface deuterons are likely delocalized: dissociatively and molecularly absorbed states are no longer distinguishable.
    Language English
    Publishing date 2016--01
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c6cp01397j
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Controlling CH2 dissociation on Ru(0001) through surface site blocking by adsorbed hydrogen

    Kirsch, Harald / Martin Wolf / R. Kramer Campen / Sergey V. Levchenko / Xunhua Zhao / Zefeng Ren

    Journal of catalysis. 2014 Dec., v. 320

    2014  

    Abstract: Understanding the relative stability of CHx species on surfaces is necessary for mechanistic description of much important catalytic chemistry. Here, we experimentally quantify the barrier of the reaction CH2→CH+H on Ru(0001) in UHV and find an ... ...

    Abstract Understanding the relative stability of CHx species on surfaces is necessary for mechanistic description of much important catalytic chemistry. Here, we experimentally quantify the barrier of the reaction CH2→CH+H on Ru(0001) in UHV and find an activation energy, 65±6kJ/mol, that is >4× higher than previous computational results with 0, 1, or 2 coadsorbed H atoms per CH2, i.e. 16kJ/mol. Employing density functional theory calculations, we show that this disagreement can be reconciled if 3 coadsorbed H atoms per CH2 are present in our experiment. We further demonstrate, by calculating the surface phase diagram for one carbon species on Ru(0001) as a function of H2 chemical potential, that the additional hydrogen surface coverage requires non-equilibrium conditions. Such conditions may be important at the high temperatures and pressures of real catalytic systems.
    Keywords activation energy ; carbon ; density functional theory ; dissociation ; hydrogen ; physical phases ; temperature
    Language English
    Dates of publication 2014-12
    Size p. 89-96.
    Publishing place Elsevier Inc.
    Document type Article
    ZDB-ID 1468993-5
    ISSN 0021-9517
    ISSN 0021-9517
    DOI 10.1016/j.jcat.2014.09.023
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: Optically probing Al-O and O-H vibrations to characterize water adsorption and surface reconstruction on α-alumina: an experimental and theoretical study.

    Tong, Yujin / Wirth, Jonas / Kirsch, Harald / Wolf, Martin / Saalfrank, Peter / Campen, R Kramer

    The Journal of chemical physics

    2015  Volume 142, Issue 5, Page(s) 54704

    Abstract: Oxide/water interfaces are ubiquitous in a wide variety of applications and the environment. Despite this ubiquity, and attendant decades of study, gaining molecular level insight into water/oxide interaction has proven challenging. In part, this ... ...

    Abstract Oxide/water interfaces are ubiquitous in a wide variety of applications and the environment. Despite this ubiquity, and attendant decades of study, gaining molecular level insight into water/oxide interaction has proven challenging. In part, this challenge springs from a lack of tools to concurrently characterize changes in surface structure (i.e., water/oxide interaction from the perspective of the solid) and O-H population and local environment (i.e., water/oxide interaction from the water perspective). Here, we demonstrate the application of surface specific vibrational spectroscopy to the characterization of the interaction of the paradigmatic α-Al2O3(0001) surface and water. By probing both the interfacial Al-O (surface phonon) and O-H spectral response, we characterize this interaction from both perspectives. Through electronic structure calculation, we assign the interfacial Al-O response and rationalize its changes on surface dehydroxylation and reconstruction. Because our technique is all-optical and interface specific, it is equally applicable to oxide surfaces in vacuum, ambient atmospheres and at the solid/liquid interface. Application of this approach to additional alumina surfaces and other oxides thus seems likely to significantly expand our understanding of how water meets oxide surfaces and thus the wide variety of phenomena this interaction controls.
    Language English
    Publishing date 2015-02-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/1.4906346
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  7. Book ; Thesis: Untersuchungen zur jungquartären Boden- und Reliefentwicklung im Bergland Nordthailands am Beispiel des Einzugsgebiets des Nam Mae Chan in der Provinz Chiang Rai

    Kirsch, Harald

    (Frankfurter geowissenschaftliche Arbeiten : Ser. D, Physische Geographie ; 23)

    1998  

    Author's details von Harald Kirsch
    Series title Frankfurter geowissenschaftliche Arbeiten : Ser. D, Physische Geographie ; 23
    Language German ; English
    Size 303 S, Ill., graph. Darst, 21 cm
    Publisher Inst. für Physische Geographie
    Publishing place Frankfurt am Main
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Frankfurt (Main), 1997
    Note Zsfassung in engl. und thail. Sprache ; Literaturverz. S. 222 - 246
    ISBN 3922540627 ; 9783922540625
    Database Former special subject collection: coastal and deep sea fishing

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  8. Article ; Online: PCorral--interactive mining of protein interactions from MEDLINE.

    Li, Chen / Jimeno-Yepes, Antonio / Arregui, Miguel / Kirsch, Harald / Rebholz-Schuhmann, Dietrich

    Database : the journal of biological databases and curation

    2013  Volume 2013, Page(s) bat030

    Abstract: The extraction of information from the scientific literature is a complex task-for researchers doing manual curation and for automatic text processing solutions. The identification of protein-protein interactions (PPIs) requires the extraction of protein ...

    Abstract The extraction of information from the scientific literature is a complex task-for researchers doing manual curation and for automatic text processing solutions. The identification of protein-protein interactions (PPIs) requires the extraction of protein named entities and their relations. Semi-automatic interactive support is one approach to combine both solutions for efficient working processes to generate reliable database content. In principle, the extraction of PPIs can be achieved with different methods that can be combined to deliver high precision and/or high recall results in different combinations at the same time. Interactive use can be achieved, if the analytical methods are fast enough to process the retrieved documents. PCorral provides interactive mining of PPIs from the scientific literature allowing curators to skim MEDLINE for PPIs at low overheads. The keyword query to PCorral steers the selection of documents, and the subsequent text analysis generates high recall and high precision results for the curator. The underlying components of PCorral process the documents on-the-fly and are available, as well, as web service from the Whatizit infrastructure. The human interface summarizes the identified PPI results, and the involved entities are linked to relevant resources and databases. Altogether, PCorral serves curator at both the beginning and the end of the curation workflow for information retrieval and information extraction. Database URL: http://www.ebi.ac.uk/Rebholz-srv/pcorral.
    MeSH term(s) Data Mining/methods ; Humans ; MEDLINE ; Protein Interaction Maps ; Proteins/metabolism ; Search Engine ; Software ; Vocabulary ; Workflow
    Chemical Substances Proteins
    Language English
    Publishing date 2013-05-02
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2496706-3
    ISSN 1758-0463 ; 1758-0463
    ISSN (online) 1758-0463
    ISSN 1758-0463
    DOI 10.1093/database/bat030
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Measuring prediction capacity of individual verbs for the identification of protein interactions.

    Rebholz-Schuhmann, Dietrich / Jimeno-Yepes, Antonio / Arregui, Miguel / Kirsch, Harald

    Journal of biomedical informatics

    2010  Volume 43, Issue 2, Page(s) 200–207

    Abstract: Motivation: The identification of events such as protein-protein interactions (PPIs) from the scientific literature is a complex task. One of the reasons is that there is no formal syntax to denote such relations in the scientific literature. ... ...

    Abstract Motivation: The identification of events such as protein-protein interactions (PPIs) from the scientific literature is a complex task. One of the reasons is that there is no formal syntax to denote such relations in the scientific literature. Nonetheless, it is important to understand such relational event representations to improve information extraction solutions (e.g., for gene regulatory events). In this study, we analyze publicly available protein interaction corpora (AIMed, BioInfer, BioCreAtIve II) to determine the scope of verbs used to denote protein interactions and to measure their predictive capacity for the identification of PPI events. Our analysis is based on syntactical language patterns. This restriction has the advantage that the verb mention is used as the independent variable in the experiments enabling comparability of results in the usage of the verbs. The initial selection of verbs has been generated from a systematic analysis of the scientific literature and existing corpora for PPIs. We distinguish modifying interactions (MIs) such as posttranslational modifications (PTMs) from non-modifying interactions (NMIs) and assumed that MIs have a higher predictive capacity due to stronger scientific evidence proving the interaction. We found that MIs are less frequent in the corpus but can be extracted at the same precision levels as PPIs. A significant portion of correct PPI reportings in the BioCreAtIve II corpus use the verb "associate", which semantically does not prove a relation. The performance of every monitored verb is listed and allows the selection of specific verbs to improve the performance of PPI extraction solutions. Programmatic access to the text processing modules is available online (www.ebi.ac.uk/webservices/whatizit/info.jsf) and the full analysis of Medline abstracts will be made through the Web pages of the Rebholz group.
    MeSH term(s) Computational Biology/methods ; Data Mining/methods ; Gene Regulatory Networks ; Natural Language Processing ; Protein Interaction Mapping/methods ; Protein Processing, Post-Translational ; Proteins/metabolism ; Signal Transduction ; Vocabulary, Controlled
    Chemical Substances Proteins
    Language English
    Publishing date 2010-04
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2057141-0
    ISSN 1532-0480 ; 1532-0464
    ISSN (online) 1532-0480
    ISSN 1532-0464
    DOI 10.1016/j.jbi.2009.09.007
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Distributed modules for text annotation and IE applied to the biomedical domain.

    Kirsch, Harald / Gaudan, Sylvain / Rebholz-Schuhmann, Dietrich

    International journal of medical informatics

    2006  Volume 75, Issue 6, Page(s) 496–500

    Abstract: Biological databases contain facts from scientific literature that have been curated by hand to ensure high quality. Curation is time-consuming and can be supported by information extraction methods. We present a server software infrastructure which ... ...

    Abstract Biological databases contain facts from scientific literature that have been curated by hand to ensure high quality. Curation is time-consuming and can be supported by information extraction methods. We present a server software infrastructure which allows to easily plug in modules to identify biologically interesting pieces of text to be then presented in a web interface to the curator. There are modules which identify UniProt, UMLS and GO terminology, gene and protein names, mutations and protein-protein interactions. UniProt, UMLS and GO concepts are automatically linked to the original source. The module for mutations is based on syntax patterns and the one for protein-protein interactions relies on chunk parsing. All modules work as separate servers possibly distributed on different machines and can be combined into processing pipelines as necessary. Communication is based on XML annotated text streams, each server processing the XML elements it is designed for, and possibly adding more information in the form of XML annotation. The server and the underlying software are available to the public.
    MeSH term(s) Abstracting and Indexing as Topic/methods ; Artificial Intelligence ; Biology ; Database Management Systems ; Documentation/methods ; Information Storage and Retrieval/methods ; Medicine ; Natural Language Processing ; Periodicals as Topic ; Semantics ; Software ; Terminology as Topic ; User-Computer Interface ; Vocabulary, Controlled
    Language English
    Publishing date 2006-06
    Publishing country Ireland
    Document type Journal Article
    ZDB-ID 1466296-6
    ISSN 1872-8243 ; 1386-5056
    ISSN (online) 1872-8243
    ISSN 1386-5056
    DOI 10.1016/j.ijmedinf.2005.06.011
    Database MEDical Literature Analysis and Retrieval System OnLINE

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