Binary systems: implications for outflows & periodicities relevant to masers

Bipolar molecular outflows have been observed and studied extensively in the past, but some recent observations of periodic variations in maser intensity pose new challenges. Even quasi-periodic maser flares have been observed and reported in the literature. Motivated by these data, we have tried to study situations in binary systems with specific attention to the two observed features, i.e., the bipolar flows and the variabilities in the maser intensity. We have studied the evolution of spherically symmetric wind from one of the bodies in the binary system, in the plane of the binary. Our approach includes the analytical study of rotating flows with numerical computation of streamlines of fluid particles using PLUTO code. We present the results of our findings assuming simple configurations, and discuss the implications.Comment: 5 pages, 3 figures, Proceedings IAU Symposium No. 287, 2012, Cosmic masers - from OH to H

Bis{1,2-bis­[bis­(3-meth­oxy­prop­yl)phosphan­yl]ethane-κ2 P,P′}dichlorido­osmium(II)

In the centrosymmetric title compound, [OsCl2(C18H40O4P2)2], the OsII atom adopts a trans-OsCl2P4 geometry, arising from its coordination by two chelating diphosphane ligands and two chloride ions. One of the meth­oxy side chains of the ligand is disordered over two orientations in a 0.700 (6):0.300 (6) ratio

A high-sensitivity 6.7 GHz methanol maser survey toward H2O sources

We present the results of a high sensitivity survey for 6.7 GHz methanol masers towards 22 GHz water maser using the 100 m Efflesberg telescope. A total of 89 sources were observed and 10 new methanol masers were detected. The new detections are relatively faint with peak flux densities between 0.5 and 4.0 Jy. A nil detection rate from low-mass star forming regions enhances the conclusion that the masers are only associated with massive star formation. Even the faintest methanol maser in our survey, with a luminosity of 1.1 $10^{-9} L_\odot$ is associated with massive stars as inferred from its infrared luminosity.Comment: Accepted for publication in A&

Orbital correlations and magnetic phase transitions in lightly doped La0.88MnOx and LaMn0.94Oy manganites

The results of X-ray and neutron diffraction study as well as the elastic, magnetic, and electrotransport properties of La$\text{}_{0.88}$MnO$\text{}_{x}$ (2.82≤ x≤2.96) and LaMn$\text{}_{0.94}$O$\text{}_{y}$ (2.91≤ y≤3.00)$ manganites have been presented. Under oxygen doping, the transitions from antiferromagnetic to ferromagnetic or spin-glass state are observed for La-deficient and La-excessive series, respectively. These transitions have been found to correlate with the change of the type of Jahn-Teller distortions from static to dynamic ones. The dynamic orbital correlations favor a ferromagnetic state, while an A-type antiferromagnetic state is typical of the static Jahn-Teller distortions. It is argued that the canting magnetic structure in manganites is not realized. The transition to a ferromagnetic or spin-glass state occurs via the formation of inhomogeneous state with different types of orbital correlations and magnetic structure. The key role of intrinsic chemical inhomogeneity in the formation of inhomogeneous magnetic states in solid solutions of manganites is emphasized

Reduction of Borazines Mediated by Low‐Valent Chromium Species

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95578/1/13168_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/95578/2/anie_201206668_sm_miscellaneous_information.pd

Evaluating Activity for Hydrogen-Evolving Cobalt and Nickel Complexes at Elevated Pressures of Hydrogen and Carbon Monoxide

Molecular cobalt and nickel complexes are among the most promising homogeneous systems for electrocatalytic hydrogen evolution. However, there has been little exploration into the effect of gaseous co-additives such as CO and H_2, which may be present in operating hydrogen-evolving or carbon-dioxide reduction systems, on the performance of these molecular electrocatalysts. In this report, we investigate the electrocatalytic activity of six cobalt and nickel complexes supported by tetraazamacrocyclic or diazadiphosphacyclooctane ligands for the reduction of p-toluenesulfonic acid to hydrogen in acetonitrile under inert atmosphere and in the presence of CO and H_2. We present an elevated-pressure electrochemical apparatus capable of reaching CO and H_2 pressures of ca. 15–520 pounds per square inch (psia) (∼1–35 atm), and we use this apparatus to determine binding constants for CO addition for each catalyst and study the inhibition of the electrocatalysis as a function of CO and H_2 pressure. In the case of CO, the extent of catalytic inhibition is correlated to the binding constant, with the cobalt complexes showing a greater degree of catalyst inhibition compared to the nickel complexes. In the case of H2, no complex showed appreciable electrocatalytic inhibition even at H_2 pressures of ca. 500 psia

Borazineâ CF3â Adducts for Rapid, Room Temperature, and Broad Scope Trifluoromethylation

A fluoroformâ derived borazine CF3â transfer reagent is used to effect rapid nucleophilic reactions in the absence of additives, within minutes at 25â °C. Inorganic electrophiles spanning seven groups of the periodic table can be trifluoromethylated in high yield, including transition metals used for catalytic trifluoromethylation. Organic electrophiles included (hetero)arenes, enabling Câ H and Câ X trifluoromethylation reactions. Mechanistic analysis supports a dissociative mechanism for CF3â transfer, and cation modification afforded a reagent with enhanced stability.Von Fluoroform abgeleitet wurde ein stabiles Reagenz für nukleophile Trifluormethylierungen anorganischer und organischer Elektrophile (E) bei Raumtemperatur. Das Reaktionsspektrum umfasst 18 anorganische Elemente, nucleophile aromatische Substitutionen sowie CF3â â Additionen an Carbonylverbindungen und Imine. Kinetische Studien sprechen für einen dissoziativen Mechanismus.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141871/1/ange201711316-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141871/2/ange201711316.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141871/3/ange201711316_am.pd

A Survey of OH Masers Towards High Mass Protostellar Objects

We present a survey of OH maser emission towards a sample of high mass protostellar objects made using the Nancay and GBT telescopes.OH maser emission was detected towards 63 objects with 36 new detections. There are 56 star-forming regions and 7 OH/IR candidates. There is no evidence that sources with OH masers have a different range of luminosities from the non-maser sources. The results of this survey are compared with previous water and class II methanol maser observations of the same objects. Some of the detected sources are only associated with OH masers and some sources are only associated with the 1720 MHz OH maser line. The velocity range of the maser emission suggests that the water maser sources may be divided into two groups. The detection rates and velocity range of the OH and Class II methanol masers support the idea that there is a spatial association of the OH and Class II methanol masers. The sources span a wide range in R, the ratio of the methanol maser peak flux to OH 1665 MHz maser peak flux, however there are only a few sources with intermediate values of R, 8<R<32, which has characterised previous samples. Sources which have masers of any species, OH, water or methanol, have redder [100um-12um] IRAS colours than those without masers. However, there is no evidence for different maser species tracing different stages in the evolution of these young high mass sources. Previous observations which have shown that the OH maser emission from similar sources traces the circumstellar disks around the objects. This combined with the sensitivity of the OH emission to the magnetic field, make the newly detected sources interesting candidates for future follow-up at high angular resolution.Comment: Accepted for publication in A&

Reductive C−C Coupling from α,β‐Unsaturated Nitriles by Intercepting Keteniminates

We present an atom‐economic strategy to catalytically generate and intercept nitrile anion equivalents using hydrogen transfer catalysis. Addition of α,β‐unsaturated nitriles to a pincer‐based Ru−H complex affords structurally characterized κ‐N‐coordinated keteniminates by selective 1,4‐hydride transfer. When generated in situ under catalytic hydrogenation conditions, electrophilic addition to the keteniminate was achieved using anhydrides to provide α‐cyanoacetates in high yields. This work represents a new application of hydrogen transfer catalysis using α,β‐unsaturated nitriles for reductive C−C coupling reactions.Eine atomökonomische Strategie zur katalytischen Erzeugung und Verwendung von Nitrilanion‐Äquivalenten basiert auf Wasserstofftransferkatalyse. Die Addition von α,β‐ungesättigten Nitrilen an einen Ru‐H‐Pinzettenkomplex generiert durch selektiven 1,4‐Hydridtransfer Keteniminate, die in einer hydrierenden Acylierung eingesetzt wurden.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149558/1/ange201904530_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149558/2/ange201904530-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149558/3/ange201904530.pd