CORRECTED 10 JUNE 2011; SEE LAST PAGE
REPORTS
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magnetic field has to be coherent over a large
fraction of the emission site (5). Such a coherent
magnetic-field structure may indicate a jet origin
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structure is formed in the BH vicinity, possibly
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The spectrum observed above 400 keV is
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Soft Gamma-Ray Imager (sensitive in the 15- to
1000-keV band), and once in the lower CsI layer,
Pixelated CsI Telescope (sensitive in the 200-keV to
10-MeV band), and whose reconstructed energy was in
the 250- to 2000-keV energy range. These events
were automatically selected on board through a time
coincidence algorithm. The maximal allowed time window
was set to 3.8 ms during our observations, which span
between 2003 and 2009, for a total exposure of more than
5 million seconds, which is ~58 days.
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Acknowledgments: ISGRI has been realized and maintained
in flight by CEA-Saclay/IRFU with the support of Centre
National d’Etudes Spatiales. Based on observations with
INTEGRAL, a European Space Agency (ESA) project with
instruments and science data center funded by ESA
member states (especially the Principal Investigator
countries: Denmark, France, Germany, Italy, Switzerland,
and Spain), Czech Republic and Poland, and with the
participation of Russia and the United States. We
acknowledge partial funding from the European Com-
mission under contract ITN 215212 “Black Hole
Universe” and from the Bundesministerium für Wirtschaft
und Technologie under Deutsches Zentrum für Luft-
und Raumfahrt grant 50 OR 1007. K.P. acknowledges
support by NASA’s INTEGRAL Guest Observer grants
NNX08AE84G, NNX08AY24G, and NX09AT28G. We thank
S. Corbel for useful comments.
23 November 2010; accepted 3 March 2011
Published online 24 March 2011;
10.1126/science.1200848
ergy loss is about 1 month (27), could also be the Selective, Nickel-Catalyzed
origin of the TeV photons detected from Cygnus
X-1 with the Major Atmospheric Gamma-ray
Imaging Cerenkov telescope experiment (30) and
possibly also the gamma rays claimed by Astro-
rivelatore Gamma ad Immagini Leggero/Light
Hydrogenolysis of Aryl Ethers
Alexey G. Sergeev and John F. Hartwig*
Imager for Gamma-Ray Astrophysics (31).
Selective hydrogenolysis of the aromatic carbon-oxygen (C-O) bonds in aryl ethers is an unsolved
The position angle (PA) of the electric vec- synthetic problem important for the generation of fuels and chemical feedstocks from biomass and for
tor, which gives the direction of the electric field the liquefaction of coal. Currently, the hydrogenolysis of aromatic C-O bonds requires heterogeneous
lines projected onto the sky, is 140° T 15°. This catalysts that operate at high temperature and pressure and lead to a mixture of products from
is at least 100° away from the compact radio jet, competing hydrogenolysis of aliphatic C-O bonds and hydrogenation of the arene. Here, we report
which is observed at a PA of 21° to 24° (32). Such hydrogenolyses of aromatic C-O bonds in alkyl aryl and diaryl ethers that form exclusively arenes and alcohols.
deviations between the electric field vector and This process is catalyzed by a soluble nickel carbene complex under just 1 bar of hydrogen at temperatures
jet direction are also found in other jet sources, of 80 to 120°C; the relative reactivity of ether substrates scale as Ar-OAr>>Ar-OMe>ArCH2-OMe (Ar, Aryl; Me,
such as Active Galactic Nuclei (33) or the galac- Methyl). Hydrogenolysis of lignin model compounds highlights the potential of this approach
tic source SS433 (34).
for the conversion of refractory aryl ether biopolymers to hydrocarbons.
References and Notes
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cellulosic biomass, and the liquefaction of these
Department of Chemistry, University of Illinois, 600 South
bonds could facilitate the liquification of this car-
bon source and its conversion to arene feedstocks
(6). A general, mild method for reductive cleav-
Matthews Avenue, Urbana, IL 61801, USA.
*To whom correspondence should be addressed. E-mail:
439