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  • 1
    Publication Date: 2010-06-04
    Description: Large amounts (estimates range from 70 Tg per year to 300 Tg per year) of the potent greenhouse gas methane are oxidized to carbon dioxide in marine sediments by communities of methanotrophic archaea and sulphate-reducing bacteria, and thus are prevented from escaping into the atmosphere. Indirect evidence indicates that the anaerobic oxidation of methane might proceed as the reverse of archaeal methanogenesis from carbon dioxide with the nickel-containing methyl-coenzyme M reductase (MCR) as the methane-activating enzyme. However, experiments showing that MCR can catalyse the endergonic back reaction have been lacking. Here we report that purified MCR from Methanothermobacter marburgensis converts methane into methyl-coenzyme M under equilibrium conditions with apparent V(max) (maximum rate) and K(m) (Michaelis constant) values consistent with the observed in vivo kinetics of the anaerobic oxidation of methane with sulphate. This result supports the hypothesis of 'reverse methanogenesis' and is paramount to understanding the still-unknown mechanism of the last step of methanogenesis. The ability of MCR to cleave the particularly strong C-H bond of methane without the involvement of highly reactive oxygen-derived intermediates is directly relevant to catalytic C-H activation, currently an area of great interest in chemistry.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scheller, Silvan -- Goenrich, Meike -- Boecher, Reinhard -- Thauer, Rudolf K -- Jaun, Bernhard -- England -- Nature. 2010 Jun 3;465(7298):606-8. doi: 10.1038/nature09015.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Organic Chemistry, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20520712" target="_blank"〉PubMed〈/a〉
    Keywords: Anaerobiosis ; *Biocatalysis ; Gases/metabolism ; Kinetics ; Mesna/analogs & derivatives/metabolism ; Methane/*biosynthesis/*metabolism ; Methanobacteriaceae/*enzymology ; Methylation ; Models, Biological ; Nickel/*metabolism ; Oxidation-Reduction ; Oxidoreductases/*metabolism ; Temperature
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2016-03-16
    Description: Overexpression of TNF contributes to pathogenesis of multiple autoimmune diseases, accounting for a remarkable success of anti-TNF therapy. TNF is produced by a variety of cell types, and it can play either a beneficial or a deleterious role. In particular, in autoimmunity pathogenic TNF may be derived from restricted cellular...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 3
    Publication Date: 2016-02-26
    Description: The oxidation of methane with sulfate is an important microbial metabolism in the global carbon cycle. In marine methane seeps, this process is mediated by consortia of anaerobic methanotrophic archaea (ANME) that live in syntrophy with sulfate-reducing bacteria (SRB). The underlying interdependencies within this uncultured symbiotic partnership are poorly understood. We used a combination of rate measurements and single-cell stable isotope probing to demonstrate that ANME in deep-sea sediments can be catabolically and anabolically decoupled from their syntrophic SRB partners using soluble artificial oxidants. The ANME still sustain high rates of methane oxidation in the absence of sulfate as the terminal oxidant, lending support to the hypothesis that interspecies extracellular electron transfer is the syntrophic mechanism for the anaerobic oxidation of methane.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scheller, Silvan -- Yu, Hang -- Chadwick, Grayson L -- McGlynn, Shawn E -- Orphan, Victoria J -- New York, N.Y. -- Science. 2016 Feb 12;351(6274):703-7. doi: 10.1126/science.aad7154.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26912857" target="_blank"〉PubMed〈/a〉
    Keywords: Anaerobiosis ; *Carbon Cycle ; Electron Transport ; Geologic Sediments/microbiology ; Methane/*metabolism ; Methanosarcinales/classification/genetics/*metabolism ; Molecular Sequence Data ; Oxidation-Reduction ; Phylogeny ; RNA, Archaeal/classification/genetics ; Seawater/microbiology ; Sulfates/*metabolism ; Sulfur-Reducing Bacteria/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    In:  EPIC3Proceedings of the 9th International Conference on Permafrost, June 29 - July 3, 2008, University of Alaska, Fairbanks, USA, pp. 1589-1594
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 13 (1971), S. 179-186 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Zusammenfassung Es wird ein einfacher Aufbau zur experimentellen Bestimmung von Nichtdiagonalelementen des magnetischen Suszeptibilitätstensors im Mikrowellenbereich angegeben. Die Magnetisierungsänderung bei Mikrowellen-Absorption (MMA) wird beobachtet und führt unmittelbar zur Suszeptibilitätχ′ yx (ω). Die angegebene Methode eignet sich für magnetische Systeme, deren longitudinale Relaxationszeiten größer als 10−6 sec sind. Außerdem erlaubt das MMA-Verfahren zwischen para-, ferro- und antiferromagnetischer Ordnung zu unterscheiden, woraus magnetische Umwandlungstemperaturen bestimmt werden können.
    Abstract: Résumé Nous décrivons un montage simple pour la détermination expérimentale des éléments nondiagonaux du tenseur de susceptibilité magnétique dans le domaine des micro-ondes. La variation de la magnétisation pendant l'absorption des micro-ondes (MMA) est mesurée et mène directement à la susceptibilitéχ′ yx (ω). La méthode peut être appliquée à des systèmes magnétiques ayant des temps de relaxation longitudinale supérieures à 10−6 sec. La méthode MMA permet de décider de l'ordre para, férro ou antiférromagnétique de l'échantillon, d'où les températures de transition magnétique peuvent être déduite.
    Notes: Abstract A simple set-up for the determination of non-diagnonal elements of the magnetic susceptibility tensor in the microwave region is given. The change of the magnetization during microwave absorption (MMA) is detected and leads directly to the susceptibilityχ′ yx (ω). The method is applicable to magnetic systems having longitudinal relaxation times larger than 10−6 sec. The MMA-method enables one to decide whether the sample is para-, ferro- or antiferromagnetic and from this magnetic transition temperatures can be measured.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 5 (1966), S. 48-57 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Résumé On a étudié à 4,2°K et 9,2 GHz l'absorption de la résonance paramagnétique de l'erbium trivalent dans les monocristaux du sesquioxide d'yttrium Y2O3, aux points de symétrie C3i et C2 du champ cristallin. Les valeurs des tenseursg et les valeurs de la structure hyperfine parallèle aux axes des champs cristallins sont:g ‖=12,176,g ⊥=3,319,A=426,4·10−4 cm−1 etg z =12,314,g x =1,645,g y =4,892,A z =433,2·10−4 cm−1. Pour les ions aux points de symétrie C2, les axes principaux deg dans le plan perpendiculaire àz se trouvent 2° de part et d'autre des directions [100]. Ce résultat est différent du cas de l'ytterbium dans Y2O3. On a exprimég en fonction de l'angle de rotation dans les plans (001), (110) et (111).
    Abstract: Abstract The paramagnetic resonance absorption of trivalent erbium in single crystals of Y2O3 on sites of crystal field symmetry C3i and C2 is investigated at 4.2°K and 9.2 kMc/s. The values of theg-tensors and those of the hyperfine structure parallel to the axes of crystalline fields are:g ‖=12.176,g ⊥=3.319,A=426.4·10−4 cm−1, andg z =12.314,g x =1.645,g y =4.892, andA z =433.2·10−4 cm−1 for the C3i-ions and the C2-ions, respectively. For ions on sites of symmetry C2 the principal axes ofg in the plane perpendicular toz are found ± 2° beside the [100]-directions. This is different from the result on Yb3+ in Y2O3. The dependency ofg on the angle of rotation is determined for the (001)-, (110)-, and (111)-plane.
    Notes: Zusammenfassung Die paramagnetische Resonanzabsorption von dreiwertigem Erbium in Einkristallen von Y2O3 an Plätzen der Punktsymmetrie C3i und C2 wurde bei 4,2°K und 9,2 GHz untersucht. Die Hauptachsenwerte derg-Tensoren und die Hyperfeinstruktur-Parameter parallel zu den Kristallfeldachsen der beiden Ionensorten sind:g ‖=12,176,g ⊥=3,319,A=426,4·10−4cm−1 für die C3i-Ionen undg z =12,314,g x =1,645,g y =4,892 undA z =433,2·10−4 cm−1 für die C2-Ionen. Im Gegensatz zum Yb3+ in Y2O3 liegen die Hauptachsen vong für die Ionen auf Plätzen der Symmetrie C2 in der zuz senkrechten Ebene um ± 2° neben den [100]-Richtungen. Für die (001)-, (110)- und (111)-Ebene wird die Winkelabhängigkeit vong angegeben.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 13 (1971), S. 268-272 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Zusammenfassung Die beiden Suszeptibilitätenχ′ yx undχ″ xx wurden im Mikrowellenbereich am hexagonalen GdCl3 gemessen. Die Abhängigkeit der Signalmaxima von der Temperatur stimmt mit früheren Berechnungen gut überein. Eine neue Methode zur Beobachtung der spontanen Magnetisierung wurde an verschiedenen Probenformen getestet, die Ergebnisse stimmen mit den Erwartungen überein. Die magnetische Umwandlungstemperatur istT C=(2,22±0,02) K.
    Notes: Abstract The two susceptibilitiesχ′ yx andχ′ xx are measured in the microwave region for the hexagonal GdCl3. The temperature dependence of the maxima of the signals shows good agreement with previous calculations. A new method of observing the spontaneous magnetization has been tested on different sample-shapes and the results coincide with the expected values. The magnetic transitions temperature isT C=(2.22±0.02) K.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 6 (1967), S. 100-104 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paramagnetic resonance of Nd3+ in Y2O3 has been measured at 4.2°K and 9.25 kMe/s. The values of theg-tensors are: ions onC 3i -sites:g ∥=2.434±0.007;g ⊥=0.702±0.005; ions onC 2-sites:g x =4.395±0.012;g y =0.433±0.009;g z =1.648±0.006. Further measurements have been performed on La2O3 crystals doped with Ce3+, Dy3+, and Er3+; the results are (C 3v -sites only): $$\begin{gathered} Ce^{3 + } :g_\parallel = 0.246 \pm 0.010,g_ \bot = 1.832 \pm 0.005 \hfill \\ Dy^{3 + } :g_\parallel = 1.586 \pm 0.006,g_ \bot = 10.096 \pm 0.015 \hfill \\ A^{161} = (0.00448 \pm 0.0002)cm^{ - 1} ,B^{161} = (0.0290 \pm 0.0002)cm^{ - 1} \hfill \\ A^{163} = (0.00618 \pm 0.0002)cm^{ - 1} ,B^{163} = (0.0400 \pm 0.0002)cm^{ - 1} \hfill \\ Er^{3 + } :g_\parallel = 13.143 \pm 0.015,g_ \bot = 3.009 \pm 0.008 \hfill \\ A^{167} = (0.0457 \pm 0.0003)cm^{ - 1} ,B^{167} = (0.0106 \pm 0.0003)cm^{ - 1} \hfill \\ \end{gathered}$$ .
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 13 (1971), S. 187-192 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Zusammenfassung Die beiden Elementeχ′ yx undχ″ xx des magnetischen Suszeptibilitätstensors werden am kubischen Ferromagneten EuO bei Mikrowellenfrequenzen untersucht. Diese beiden Elemente stimmen dann überein, wenn das statische Magnetfeld groß genug ist, Domänen in der Probe zu beseitigen. Dies stimmt mit theoretischen Überlegungen überein und gibt einen Hinweis auf die Struktur des Hamilton-Operators. Die magnetische Umwandlungstemperatur wurde zuT c=(69,2±0,2)°K bestimmt, in Übereinstimmung mit dem Wert aus Messungen der spezifischen Wärme.
    Abstract: Résumé Les deux élémentsχ′ yx etχ″ xx du tenseur de susceptibilité magnétique sont étudiés pour le monoxide d'europium cubique et férromagnétique pour des fréquences de micro-ondes. Les deux éléments coïncident si le champ magnétique statique est assez grand pour faire disparaître la structure des domaines dans l'échantillon. Cela est en accord avec des prédictions théoriques et donne une indication sur la structure de l'opération de Hamilton. La température de transition magnétique a été évaluée àT c=(69.2±0.2)°K en accord avec le résultat de mesures de la chaleur spécifique.
    Notes: Abstract The two elementsχ′ yx andχ″ xx of the magnetic susceptibility tensor for the cubic ferromagnetic EuO are investigated at microwave frequencies. It is shown that these two elements coincide when the magnetic field is large enough to remove the domain structure within the sample. This is in coincidence with theoretical predictions and shows a certain structure of the Hamiltonian. The magnetic transition temperature is found to beT c=(69.2±0.2)°K in agreement with the result from specific heat measurement.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 231 (1970), S. 377-396 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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