Faecalibacterium prausnitzii : from microbiology to diagnostics and prognostics

We thank Dr Xavier Aldeguer and MD David Busquets from the Hospital Dr Josep Trueta (Girona, Spain) and M.D Míriam Sabat Mir from the Hospital Santa Caterina (Salt, Spain) for their help and critical discussion concerning clinical aspects. This work was partially funded by the Spanish Ministry of Education and Science through the projects SAF2010-15896 and SAF2013-43284-P, which has been co-financed with FEDER funds. Dr Sylvia H Duncan acknowledges support from the Scottish Government Food, Land and People program.Peer reviewedPostprin

A computer modeling study of partially coherent f.c.c.:b.c.c. boundaries

A computer modeling study has been made of the structure of f.c.c.:b.c.c. boundaries which are expected to be partially coherent. These boundaries are defined by {111}f.c.c∥{110}b.c.c and a rotation about an axis normal to these conjugate habit planes leading to orientation relationships ranging from Nishiyama-Wasserman to beyond Kurdjumov-Sachs. A wide range of ratios of the f.c.c. to the b.c.c. lattice parameter was employed. Regions of good atomic matching exist in the {111}f.c.c∥{110}b.c.c interface for all orientation relationships and lattice parameter ratios investigated. Extending the study of Hall et al., incorporation of structural ledges in the boundary allows the switching of matching layers and results in an increase in the interfacial coherency. The interledge spacing is a function of orientation and lattice parameter ratio and varies from ca. 3 to 30 Å. The structural ledges result in a deviation of the apparent habit plane from {111}γ although on an atomic scale this plane is always retained. The amount of deviation of the apparent habit plane from {111}γ is a function of orientation and lattice parameter ratio. Interfacial misfit dislocations lie midway between coherent regions on the broad faces of the structural ledges. The misfit dislocations consist of a single array whose spacing is a function of the orientation and lattice parameter ratio and ranges from ca. 8 to 40 Å. At least one partially coherent interface, normally incorporating both structural ledges and misfit dislocations, is predicted for each orientation and lattice parameter ratio investigated. In every case, the misfit dislocations are sessile with respect to slip out of the atomic conjugate habit planes, thus making a martensitic f.c.c. → b.c.c. transformation mechanistically impossible for these interfaces. © 1979

The interfacial structure of the broad faces of ferrite plates

An investigation of the interfacial structure at the broad faces of ferrite plates embedded in retained austenite has been undertaken in an Fe-0.62 wt% C-2.0 wt% Si alloy by means of weakbeam dark-field TEM. These boundaries have been shown to be partially coherent and to contain single arrays of parallel misfit dislocations spaced ca. 15 to 25 Å apart and arrays of parallel structural ledges spaced ca. 22 to 90 Å apart. The dislocations are mixed in character and have lattice-type Burgers vectors lying in the atomic habit planes of the interface. The structural ledges are triatomic in height, with spacings and directions varying with the rotation of {111}γ relative to {110}α, about a common orthogonal axis. Data on apparent habit planes and orientation relationships were obtained with stereographic projection and trace analysis techniques. Comparisons of these data with those obtained by means of the interface modeling techniques described in the companion paper show good agreement. The misfit dislocation structure is always sessile with respect to glide out of the interface, whereas the lattice invariant deformation portion of a martensitic f.c.c. → b.c.c. transformation requires a glissile structure; hence, it is mechanistically impossible for ferrite plates to thicken by a martensitic mechanism. © 1979