A one-shot deviation principle for stability in matching problems

This paper considers marriage problems, roommate problems with nonempty core, and college admissions problems with responsive preferences. All stochastically stable matchings are shown to be contained in the set of matchings which are most robust to one-shot deviation

Bacterial SBP56 identified as a Cu-dependent methanethiol oxidase widely distributed in the biosphere

Oxidation of methanethiol (MT) is a significant step in the sulfur cycle. MT is an intermediate of metabolism of globally significant organosulfur compounds including dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS), which have key roles in marine carbon and sulfur cycling. In aerobic bacteria, MT is degraded by a MT oxidase (MTO). The enzymatic and genetic basis of MT oxidation have remained poorly characterized. Here, we identify for the first time the MTO enzyme and its encoding gene (mtoX) in the DMS-degrading bacterium Hyphomicrobium sp. VS. We show that MTO is a homotetrameric metalloenzyme that requires Cu for enzyme activity. MTO is predicted to be a soluble periplasmic enzyme and a member of a distinct clade of the Selenium-binding protein (SBP56) family for which no function has been reported. Genes orthologous to mtoX exist in many bacteria able to degrade DMS, other one-carbon compounds or DMSP, notably in the marine model organism Ruegeria pomeroyi DSS-3, a member of the Rhodobacteraceae family that is abundant in marine environments. Marker exchange mutagenesis of mtoX disrupted the ability of R. pomeroyi to metabolize MT confirming its function in this DMSP-degrading bacterium. In R. pomeroyi, transcription of mtoX was enhanced by DMSP, methylmercaptopropionate and MT. Rates of MT degradation increased after pre-incubation of the wild-type strain with MT. The detection of mtoX orthologs in diverse bacteria, environmental samples and its abundance in a range of metagenomic data sets point to this enzyme being widely distributed in the environment and having a key role in global sulfur cycling.The ISME Journal advance online publication, 24 October 2017; doi:10.1038/ismej.2017.148

An Extended X-ray Absorption Fine-Structure Study Of The Rare-Earth Sites In A Neodymium Doped Glass

The local environment around the metal sites in a Nd doped aluminosilicate glass has been determined using extended x-ray absorption fine structure. Detailed fitting of the spectrum reveals an average Nd coordination of 4.5 +/- 1 oxygen atoms at 2.15 angstrom and 4.5 +/- 2 oxygen atoms at 2.44 angstrom; a second shell, containing silicon atoms, is centred at 3.7 angstrom. It is suggested that all the oxygen atoms are nonbridging

Structural-Analysis Of Gold Clusters Using EXAFS

ABSTRACTThree gold clusters, Au55 (PPh3 )12Cl6, Au55{PPh2(C6H4SO3Na)}12Cl6 and Au11{PPh2(p-ClC6H4)}7I3 (which we shall denote Au55, Au55, and Au11 for convenience) have been studied using EXAFS. Average near-neighbour bond lengths are contracted from the bulk by approximately 0.15Å (±0.02Å) for Au55, and 0.22Å (± 0.02Å) for Au11. Ligand contributions have been successfully modelled in the fitting. Debye-Waller factors for samples at room temperature and at 80K are compared to ascertain the relative degrees of thermal and static disorder present in the systems. Results clearly indicate that static structural disorder predominates over thermally induced vibrational disorder.</jats:p

An EXAFS Study Of Some Gold And Palladium Cluster Compounds

Gold L3-edge EXAFS measurements at 80 K on Au55(PPh3)12Cl6 confirm that the Au-Au distances in this amorphous metal cluster compound are significantly shorter than in bulk gold. The nearest-neighbor Au-Au distances are all equal within experimental uncertainty. Outer-shell Au-Au distances have also been resolved. The results are consistent with the cuboctahedral structure originally proposed for this cluster, but not the polyicosahedral one recently suggested. Very similar results have been obtained from the sulphonated water-soluble derivative Au55(PPh2C6H4SO3Na)12Cl6. In contrast, EXAFS of Au11{PPh2(p-ClC6H4)7I3 has clearly resolved the two nearest-neighbour Au-Au distances associated with its icosahedral structure. Palladium K-edge EXAFS has been used to study the cluster Pd561(phen)36O200. The Pd-Pd distance is nearly equal to that in bulk palladium. The results show a cubic close-packed cluster structure for this material, in contrast to the icosahedral structure reported for Pd561(phen)60(OAc)180

EXAFS Investigations Of High-Nuclearity Pd Clusters

Pd K-edge X-ray absorption spectra at several temperatures of Pd-561(phen)(36)O-200 and other high nuclearity ligand-stabilized Pd clusters are reported. Data-analysis performed in a wide k-range (up to 17.5 Angstrom(-1)), accounting for possible effects of asymmetry, allowed us to obtain very reliable results for the nearest neighbour Pd-Pd distribution. Mean bond length and variance are determined as a function of temperature. The data indicate the existence of regular FCC particles with a very weak relaxation with respect to the bulk ideal geometry and no asymmetry effects in the bond length distribution

A structural basis for ionic-diffusion in oxide glasses

The relationships between the environments of cations in alkali silicates measured by X-ray absorption fine structure (XAFS) and magic angle spinning nuclear magnetic resonance (MASNMR) are considered. Both are consistent with the modified random network for glass structure in which modifiers form channels percolating through the network. It is proposed that the mechanisms determining the distribution of bridging and non-bridging oxygen atoms at the glass transition are the same as those that promote ionic transport at lower temperatures in the glass. In particular the results of XAFS and MASNMR can be used to predict the activation energy for ionic transport and the magnitude of the electrical conductivity. Values of these parameters for alkali disilicates are in good agreement with those measured directly from transport properties