Stepwise evolution of the Sec machinery in Proteobacteria

The Sec machinery facilitates the translocation of proteins across and into biological membranes. In several of the Proteobacteria, this machinery contains accessory features that are not present in any other bacterial division. The genomic distribution of these features in the context of bacterial phylogeny suggests that the Sec machinery has evolved in discrete steps. The canonical Sec machinery was initially supplemented with SecB; subsequently, SecE was extended with two transmembrane segments and, finally, SecM was introduced. The Sec machinery of Escherichia coli and other Enterobacteriales represents the end product of this stepwise evolution.</p

FE calculations on a three stage metal forming process of Sandvik Nanoflex

Sandvik NanoflexTM combines good corrosion resistance with high strength. This steel has good deformability in\ud austenitic conditions. It belongs to the group of metastable austenites, which means that during deformation a strain-induced\ud transformation into martensite takes place. After deformation, transformation continues as a result of internal stresses. Both\ud transformations are stress-state and temperature dependent. A constitutive model for this steel has been formulated, based\ud on the macroscopic material behaviour measured by inductive measurements. Both the stress-assisted and the strain-induced\ud transformation into martensite have been incorporated in this model. Path-dependent work hardening has also been taken\ud into account. This article describes how the model is implemented in an internal Philips FE code called CRYSTAL, which is\ud a dedicated robust and accurate finite element solver. The implementation is based on lookup tables in combination with\ud feed-forward neural networks. The radial return method is used to determine the material state during and after plastic\ud flow, however, it has been extended to cope with the stiff character of the partial differential equation that describes the\ud transformation behaviour

Evolution of YidC/Oxa1/Alb3 insertases: three independent gene duplications followed by functional specialization in bacteria, mitochondria and chloroplasts

Members of the YidC/Oxa1/Alb3 protein family facilitate the insertion, folding and assembly of proteins of the inner membranes of bacteria and mitochondria and the thylakoid membrane of plastids. All homologs share a conserved hydrophobic core region comprising five transmembrane domains. On the basis of phylogenetic analyses, six subgroups of the family can be distinguished which presumably arose from three independent gene duplications followed by functional specialization. During evolution of bacteria, mitochondria and chloroplasts, subgroup-specific regions were added to the core domain to facilitate the association with ribosomes or other components contributing to the substrate spectrum of YidC/Oxa1/Alb3 proteins

Copper-rubber interface delamination in stretchable electronics

Next generation microelectronic devices will be flexible, rollable and capable of extreme elongations. The latter aspect enables novel applications such as skin-like human body sensors. Stretchable electronics consist of stiff microchips on a highly compliant substrate, circuited by metal wires which must be highly stretchable. Stretchability is achieved using mechanistic patterns. Ensuring interface integrity between the metallic lines and the substrate forms, however, a huge engineering challenge, making interface integrity the key limiting factor in stretchable electronics development. In the present work, interfacial delamination in the copper/rubber model interface system is characterized meticulously from (i) 90º peel tests with high-speed video imaging to obtain adhesion energies and rubber-lift geometry dimensions, (ii) microscopic visualization of the progressing delamination front using in-situ scanning electron microscopy, and (iii) modeling of peel tests using a cohesive-zones enhanced finite elements model. High adhesion energies are achieved for rough copper surfaces with deep ??valleys??. For these interfaces, energy dissipation upon delamination is dominated by the formation, stretching, and rupture of ~20¼m-long rubber fibrils. Fibrillation is triggered by hampering the debonding of rubber from the copper surface through an interplay of local surface area enlargement, complex mixed-mode loading, and mechanical interlocking in the roughness ??valleys??