F0-F1 coupling and symmetry mismatch in ATP synthase resolved in every F0 rotation step

The F0F1 ATP synthase, essential for cellular energy production, is composed of the F0 and F1 rotary motors. While both F0 and F1 have pseudo-symmetric structures, their symmetries do not match. How the symmetry mismatch is solved remains elusive due to missing intermediate structures of rotational steps. Here, for ATP synthases with 3- and 10-fold symmetries in F1 and F0, respectively, we uncovered the mechanical couplings between F0 and F1 at every 36° rotation step via molecular dynamics simulations and comparison of cryo-electron microscopy structures from three species. We found that the frustration is shared by several elements. The F1 stator partially rotates relative to the F0 stator via elastic distortion of the b-subunits. The rotor can be distorted. The c-ring rotary angles can be deviated from symmetric ones. Additionally, the F1 motor may take non-canonical structures relieving stronger frustration. Together, we provide comprehensive understanding to solve the symmetry mismatch.

Elastic distortion determining conduction in BiFeO3 phase boundaries

The localized crystallography of conducting and non-conducting phase boundaries in mixed-phase BiFeO3 is directly compared using scanning transmission electron microscopy techniques.

Chiral and achiral mechanisms of self-limiting assembly of twisted bundles

A generalized theory analyzes how the interplay between thermodynamics of twist and elastic distortion shapes the self-limiting assembly of bundles.

Operation influence on structural and phase condition of 0.12C-1Cr-1Mo-1V-Fe steel

By the method of transmission electron diffraction microscopy the study of 0.12C-1Cr-1Mo-1V-Fe steel samples subjected to various long-term operation was conducted: 1) on the unfinished sample, 2) after prolonged operation without sample destruction, and 3) after prolonged operation brought to sample destruction. For each sample the phase composition was determined and the change in morphology of the structure was studied. It is established that operation of steel leads, firstly, to the destruction of plate pearlite and intensive ferrite fragmentation, secondly, to the redistribution of carbide component and, thirdly, to elastic distortion of the crystal lattice.

Collective Diffusion of Colloidal Particles in a Liquid Crystal

The theory of collective diffusion effects in a system of colloidal particles in a liquid crystal is proposed. The specifics of diffusion which can be observed experimentally are described. The dependence of the diffusion coefficient on the temperature and particle density is found. It is shown that collective diffusion in a system of colloidal particles in a liquid crystal arises from the elastic distortion of the director field generating the interparticle interaction. The behavior of such diffusion is found to be nontrivial.

Biological growth in bodies with incoherent interfaces

A general theory of thermodynamically consistent biomechanical–biochemical growth in a body, considering mass addition in the bulk and at an incoherent interface, is developed. The incoherency arises due to incompatibility of growth and elastic distortion tensors at the interface. The incoherent interface therefore acts as an additional source of internal stress besides allowing for rich growth kinematics. All the biochemicals in the model are essentially represented in terms of nutrient concentration fields, in the bulk and at the interface. A nutrient balance law is postulated which, combined with mechanical balances and kinetic laws, yields an initial-boundary-value problem coupling the evolution of bulk and interfacial growth, on the one hand, and the evolution of growth and nutrient concentration on the other. The problem is solved, and discussed in detail, for two distinct examples: annual ring formation during tree growth and healing of cutaneous wounds in animals.

Характер деформаций на границе раздела упругих сред при условии скольжения

Fresnel coefficients obtained when solving the problem of wave propagation through the interface of two elastic media and expressions for components of the elastic-distortion tensor allow one to study the character of dynamic deformations at the interface. Deformation modes different from zero at the interface of the elastic media under the slip-contact condition have been determined. Dependences of deformation amplitudes at the interface on the wave incidence angle and parameters of the adjacent media for incident longitudinal and transverse waves have been constructed and analyzed.

Mesoscopic Description of Dislocation Patterning Using the Concept of Incompatibility of Strains

We develop a phase field model that describes the elastic distortion of a ferroelastic material with cubic anisotropy due to an arbitrary dislocation network and a uniform external load. The dislocation network is characterized using the Nye tensor and enters the formulation via a set of incompatibility constraints for the internal strain field. The long-range elastic response of the material is obtained by minimization of the free energy that accounts for higher order terms of the order parameters and symmetry-adapted strain gradients. To demonstrate the performance of the model, a minimal version of continuum dislocation dynamics is used to investigate the simultaneous evolution of the network of geometrically necessary dislocations and the internal strain field.