51 research outputs found

    How Genomics Is Changing What We Know About the Evolution and Genome of Bordetella pertussis

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    The evolution of Bordetella pertussis from a common ancestor similar to Bordetella bronchiseptica has occurred through large-scale gene loss, inactivation and rearrangements, largely driven by the spread of insertion sequence element repeats throughout the genome. B. pertussis is widely considered to be monomorphic, and recent evolution of the B. pertussis genome appears to, at least in part, be driven by vaccine-based selection. Given the recent global resurgence of whooping cough despite the wide-spread use of vaccination, a more thorough understanding of B. pertussis genomics could be highly informative. In this chapter we discuss the evolution of B. pertussis, including how vaccination is changing the circulating B. pertussis population at the gene-level, and how new sequencing technologies are revealing previously unknown levels of inter- and intra-strain variation at the genome-level

    Exploring molecular variation in Schistosoma japonicum in China

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    This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. The attached file is the published version of the article

    Synthesis of TiN thin films from titanium imido complexes

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    Thin films have been formed on glass by low pressure chemical vapour deposition from eleven closely related single-source precursors of generic form [TiCl2(NR)(L)x] (where x = 1, L = tridentate N-ligand; x = 2, 3, L = monodentate N-ligand). Most of the precursors formed titanium nitride films, however, bulkier imido complexes and those with chelating ligands tended to produce thin films with significant oxygen and carbon contamination, suggesting incomplete decomposition and post reaction oxidation. The best single-source precursor was found to be [TiCl2(NtBu)(py)3], which gave gold-coloured films of stoichiometric TiN1.0. Despite the coordination environment around the metal being essentially the same and the materials having comparable volatility, significant differences in film quality were observed

    Evaluation of the relative importance of Ti-Cl center dot center dot center dot H-N hydrogen bonds and supramolecular interactions between perfluorophenyl rings in the crystal structures of [Ti(NR)Cl-2(NHMe2)(2)] (R = Pr-i, C6H5 or C6F5)

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    The three closely-related compounds [Ti-(NiPr)Cl2(NHMe2)2] 1, [Ti(N6H5)Cl2(NHMe2)2] 2 and [Ti(NC6F5)Cl2(NHMe2)2] 3 all crystallize in the space group C2/c with the titanium atoms lying on two-fold axes at (0, y, 1/4); in compounds 1 and 2 the molecules are linked in one-dimensional infinite chains by intermolecular Ti-Cl···H-N hydrogen bonds along the direction of the crystallographic c axis, whereas in 3 offset face-to-face interactions between the C6F5 rings break down the hydrogen bonded chains

    New titanium imido synthons: syntheses and supramolecular structures.

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    Reactions of Ti(NMe(2))(2)Cl(2) with a wide range of primary alkyl and arylamines RNH(2) afforded the corresponding 5-coordinate imido titanium compounds Ti(NR)Cl(2)(NHMe(2))(2) (R = (t)Bu (1), (i)Pr (2), CH(2)Ph (3), Ph (4), 2,6-C(6)H(3)Me(2) (5), 2,6-C(6)H(3)(i)Pr(2) (6), 2,4,6-C(6)H(2)F(3) (7), 2,3,5,6-C(6)HF(4) (8), C(6)F(5) (9), 4-C(6)H(4)Cl (10), 2,3,5,6-C(6)HCl(4) (11), 2-C(6)H(4)CF(3) (12), 2-C(6)H(4)(t)Bu (13)). The compounds 1-13 are monomeric in solution but in the solid state form either N-H...Cl hydrogen bonded dimers or chains or perfluorophenyl pi-stacked chains, depending on the imido R-group. The compound 13 was also prepared in a "one-pot" synthesis from RNH(2) and Ti(NMe(2))(4) and Me(3)SiCl. Reaction of certain Ti(NR)Cl(2)(NHMe(2))(2) compounds with an excess of pyridine afforded the corresponding bis- or tris-pyridine analogues [Ti(NR)Cl(2)(py)(x)](y) (x = 3, y = 1; x = y = 2), and the structure of Ti(2)(NC(6)F(5))(2)Cl(2)(mu-Cl)(2)(py)(4) shows pi-stacking of perfluorophenyl rings. Reaction of Ti(NMe(2))(2)Cl(2) with cross-linked aminomethyl polystyrene gave quantitative conversion to the corresponding solid-supported titanium imido complex. This paper represents the first detailed study of how supramolecular structures of imido compounds may be influenced by simple variation of the imido ligand N-substituent

    A remarkable inversion of structure-activity dependence on imido N-substituents with varying co-ligand topology and the synthesis of a new borate-free zwitterionic polymerisation catalyst.

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    Ethylene polymerisation productivities of tris(pyrazolyl)methane-supported catalysts [Ti(NR){HC(Me2pz)3}Cl2] show a dramatically different dependence on the imido R-group compared to those of their TACN analogues, attributed to differences in fac-N3 donor topology; when treated with AliBu3, the zwitterionic tris(pyrazolyl)methide compound [Ti(N-2-C6H4tBu){C(Me2pz)3}Cl(THF)] also acts as a highly active, single site catalyst (TACN = 1,4,7-trimethyltriazacyclononane)

    CCDC 619784: Experimental Crystal Structure Determination

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    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
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