Features of the Tien Shan newest orogen morphostructure

Research subject. The concept of morphostructure implies the presence of a relationship between the relief forms of segments of the Earth’s crust and their structural and material content. This article describes the geological ensembles of the Tien Shan orogen, the tectonic structure and modern relief of which differ in their parameters from the general morphostructural plan and which, therefore, belong to the category of morphostructural anomalies. Materials and methods. The data presented in the article were obtained in the course of field structural-geological and morphostructural study of key segments of the Tien Shan orogen, as well as an analysis of materials from previous research, including the results of geophysical sounding of the Earth’s crust and geodesical monitoring of relative modern movements of reference points on the surface.Results. The article demonstrates that, against the background of the general linear-wave morphostructure of the Tien Shan orogen, there are areas whose relief and tectonic structure do not agree with the general tectonic plan of the mountain. Wi thin the considered region, different types of morphostructural anomalies are identified and described, reflecting the speci fics of the evolution and geotectonic position of individual volumes of upper-crust rock complexes: zones of concentrated deformation and tectonic joining; centrally symmetric structures formed on the site of paleoatolls; neotectonic protrusions of the granite basement; trans-regional zone of the Talaso-Ferghana Fault and other structures. Conclusion. The formation of morphostructural anomalies is associated with the presence of non-trivial geodynamic environments operating against the background of the tectonic regime common to the Tien Shan. The modern morphostructure of the Tien Shan is the result of interference between various geodynamic regimes and settings: a regime common to the entire territory of the orogen and particular regimes that manifest themselves sporadically and are reflected in the modern relief.

Interplay between shape and composition in bimetallic nanoparticles revealed by an efficient optimal-exchange optimization algorithm

Despite the large relevance of bimetallic metal nanoparticles for heterogeneous catalysis, the relation between their shape and elemental composition remains elusive. Here, we investigate this relationship by implementing and applying global optimization methods enhanced with a novel optimal-exchange algorithm. In particular, we determine the lowest energy chemical orderings for PtAu nanoparticles, revealing that the most stable shape changes from highly symmetric structures for pure particles to distorted and less symmetric shapes for intermediate compositions. The presented method leverages the local atomic contributions to an empirical surrogate energy expression to identify optimal atom exchanges. This also allows us to pinpoint the origin of the stability of distorted shapes, revealing a favorable energy trade-off when over-coordinating Pt and under-coordinating Au upon distorting the particle shape.

Three-Dimensional Fully pi-Conjugated Macrocycles: When Truly 3D-Aromatic and when 2D-Aromatic-in-3D?

Recently, several fully pi-conjugated macrocycles with strongly puckered or cage-type structures have been synthesized and found to exhibit aromatic character according to both experiments and computations. Herein, we examine their electronic structures and put them in relation to truly 3D-aromatic molecules (e.g., closo-boranes and certain charged fullerenes) as well as 2D-aromatic polycyclic aromatic hydrocarbons. We use qualitative theory combined with quantum chemical calculations, and find that the macrocycles explored thus far should be described as 2D-aromatic with three-dimensional structures (abbr. 2D-aromatic-in-3D) instead of truly 3D-aromatic. Besides fulfilling the 6n + 2 pi-electron rule, 3D-aromatic molecules with highly symmetric structures (e.g., Td and Oh) have a number of molecular orbital (MO) levels that are (at least) triply degenerate. At lower symmetries, the triple (or higher) orbital degeneracies should be kept in approximate sense. This last criterion is not fulfilled by macrocyclic cage molecules that are 2D-aromatic-in-3D. Their aromaticity results from a fulfillment of Hückel’s 4n + 2 rule for each individual macrocyclic path, yet, their pi-electron counts are coincidentally 6n + 2 numbers for macrocycles with three tethers of equal lengths. We instead link the 3D-macrocyclic molecules explored earlier to naphthalene, motivating their description as 2D-aromatics albeit with 3D structures. It is notable that macrocyclic cages which are 2D-aromatic-in-3D can be aromatic also when the tethers are of different lengths, i.e., when their pi-electron counts differ from 6n + 2. Finally, we identify tetrahedral and cubic pi-conjugated molecules that fulfill the 6n + 2 rule and which exhibit significant electron delocalization. Yet, their properties are similar to those of analogous compounds with electron counts that differ from 6n + 2. Thus, despite that these tetrahedral and cubic molecules show substantial pi-electron delocalization they should not be classified as true 3D-aromatics.

Para-Kenmotsu manifolds admitting semi-symmetric structures

The object of the present paper is to study para-Kenmotsu manifolds satisfying different conditions of semi-symmetric type.

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.

Total angular momenta quantization of dielectric sphere modes

Spherical particles both dielectric and metallic are essential building blocks in nanophotonics. During the recent rapid development of Mie-tronic — nanophotonics devices heavily using various features of the Mie-resonances — the deep fundamental investigation of the eigenmodes of such particles by using the novel tools is still relevant and currently important. Moreover, eigenmodes of a sphere are closely related to the Vector Spherical Harmonics (VSH) which are widely used in the multipolar decomposition to analyze less symmetric structures. In this work, we study in detail the canonical spin and angular momenta (AM), helicity, and other properties of the eigenmodes of dielectric (nondispersive) and metallic (dispersive) spheres. We show that the canonical momentum density of the AM is quantized and has a close relation to the quantum picture of a single photon. Our work provides a solid platform for future studies and applications of the AM transfer from near fields of spherical particles to the matter in its vicinity.