Type Of Symmetry Research Articles

Molecular Logic of Prokaryotic Surface Layer Structures.

Most prokaryotic cells are encased in a surface layer (S-layer) consisting of a paracrystalline array of repeating lattice-forming proteins. S-layer proteins populate a vast and diverse sequence space, performing disparate functions in prokaryotic cells, including cellular defense, cell-shape maintenance, and regulation of import and export of materials. This article highlights recent advances in the understanding of S-layer structure and assembly, made possible by rapidly evolving structural and cell biology methods. We underscore shared assembly principles revealed by recent work and discuss a common molecular framework that may be used to understand the structural organization of S-layer proteins across bacteria and archaea.

A cohomological gravity in D = 11

A [Formula: see text] cohomological gravity is introduced. The central piece is a new BRST-like symmetry [Formula: see text] with [Formula: see text] up to a diffeomorphism and gauge symmetry. The only nontrivial observable of this symmetry is a Chern–Simons integral. The construction of the symmetry requires a spin 0 fermion [Formula: see text] and a spin [Formula: see text] boson [Formula: see text] at the minimum, in addition to the standard gravity and gauge fields, to close the algebra off-shell. The gravity action is uniquely determined by requiring a field redefinition type of global symmetry between bosonic and fermionic fields. It is of a simple form [Formula: see text] plus a Chern–Simons term, and appears as the [Formula: see text] supergravity action under a special combination of the fields without independent presence of [Formula: see text] and [Formula: see text]. The [Formula: see text]-invariant path-integral measure, which is also invariant under the global symmetry, is shown to exist for the theory to be valid at quantum level. It achieves only when the fields are redefined under certain combination that is different from the special combination, and the fields in this combination are interpreted as physical fields. At [Formula: see text] limit, where all field combinations converges, the theory reduces to [Formula: see text] supergravity and the global symmetry becomes the local supersymmetry with [Formula: see text] as the local variable. At a nonvanishing [Formula: see text] limit set by residue symmetries upon broken [Formula: see text]-symmetry, the theory admits a cosmological solution that has a wavy term to allow accelerated expansion of the universe while not violate null energy condition.

Национальная культура в условиях глобализации: проблемы идентичности и диверсификации

Исследование посвящено разработке модели, характеризующей внутренний баланс национальной культуры, функционирующей в условиях глобализации между противоположными полюсами идентичности и диверсификации. Материалами послужили исследования азербайджанских и российских философов, культурологов и искусствоведов, произведения художников ХХ в. В процессе исследования на основе принципа бесфоновой организации изобразительных форм (БОИФ), разработанного Х. Мамедовым и С. Дадашевым, визуализирована мультикультурная модель. Отмечено, что язык БОИФ обладает свойствами комплементарности и полиэйконичности, то есть бесконечно интегрирует элементы в систему. Модель устойчива и структурно отражает идеи мультикультурализма. Комплементарность организует внешние формы культур, не затрагивая их содержания, что отвечает формуле «моя свобода заканчивается там, где начинается ваша». Баланс внутри национальной культуры достигается кристаллизацией этнических особенностей и внутренним разнообразием системы. The article is devoted to the development of a model that ensures the internal balance of national culture, which, in the context of globalization, functions between the opposite poles of identity and diversification. The materials are results of the studies of Azerbaijani and Russian philosophers, culturologists, and art historians, works of artists of the 20th century. The methodology is based on a comparative approach using analogies and parallels. The authors define identity as the gathering, concentration, crystallization of all the characteristic features of a given ethnic group with the uniformity, similarity of the totality of its properties. In this case, diversification is understood as diversity, dissimilarity, difference and even diversity of features within one system. It is noted that researchers often projected the laws of cultural development onto the art system as a whole, but they never inverted this scheme, trying to model the processes in culture with the help of art. The article examines the crisis of figurativeness in art expressed in the works of Kazimir Malevich, non-figurative art and works of Maurits Cornelis Escher, which are characterized by a special type of symmetry interpreted as the fundamental basis of the visual language. In the authors’ opinion, this phenomenon corresponds to the global identity crisis that resulted from the collapse of all empires (except for the British one) following the results of World War I. The parallelism of the discussed phenomena made it possible to use the pictorial language studied by Kh. Mamedov and S. Dadashev for modeling cultural processes. Based on their concept of a backgroundless organization of pictorial forms (such as an image in which the drawing is equal to the background), the authors of the article created the visualization of a multicultural model. The model’s properties and features are described, among which stability, complementarity, and polyiconicity (infinite equal integration of elements within an integral system) are distinguished, after which this model is projected by analogy on culture and various aspects of intercultural interaction. The authors note that this model, in terms of its structure, reflects the ideas of multiculturalism. The principle of complementarity organizes the external forms of cultures without affecting their internal content. This corresponds to the formula “my freedom ends where yours begins”. It is concluded that the balance within the national culture is achieved, on the one hand, by the crystallization of ethnic characteristics with which the culture identifies itself and, on the other, by the diversity that is preserved within the system.

Некоторые особенности спектра и кинетики фосфоресценции трифенилена в бромбензоле при 77 К

The spectrum and kinetics of triphenylene phosphorescence under monochromatic and broadband excitation in bromobenzene at 77 K were studied. It was found that the intensity distribution in the phosphorescence spectrum depends on the spectral composition of the exciting light. In the transition from excitation by monochromatic radiation of a nitrogen laser ($\lambda_{ex} = 337$ nm) to broadband excitation by a high-pressure xenon lamp with a filter of 313 nm, a 0--0 band gain is observed relative to the most intense vibronic band of a half-symmetric oscillation ($\nu =1605$ cm$^{-1})$. In this case, a broadening of the 0--0 band and a shift of its maximum to the short-wave region by 1.8 nm are observed. The decay of triphenylene phosphorescence under these conditions is two-exponential with characteristic decay times $\tau_{1} = 0.40$ s and $\tau_{2} = 0.13$ s. The contribution of the component damping with $\tau_{1}$ to the total intensity increases with the allocation of the short-wave section of the 0--0 band. The contribution of the component damping with $\tau_{2}$ increases with the allocation of the long-wave portion of the 0-0 band. An increase in the contribution of the component with $\tau_{2}$ is also observed with monochromatic laser excitation in comparison with broadband excitation. Based on these results, it was concluded that there are two spatially separated emission centers with different probabilities of deactivation of triplet excitations of triphenylene molecules. The interpretation of the results is based on the generally accepted literature provisions that halogen atoms (chlorine, bromine, iodine) increase the probability of spin forbidden and symmetry transitions in highly symmetric molecules such as triphenylene (symmetry type D$_{3h})$ and coronene (symmetry type D$_{6h})$. Based on a comparison of changes in the relative intensity of the 0-0 band of centers with $\tau_{1}$ and $\tau_{2}$, it was concluded that external heavy atoms (bromine) to a greater extent enhance the symmetry-forbidden transitions of centers with $\tau_{1}$ than with $\tau_{2}$. The faster attenuation of the phosphorescence of centers with $\tau_{2}$ than of centers with $\tau_{1}$ is due to a greater degree to an increase in their triplet - singlet transition forbidden along the spin.

Instability characteristics of a highly separated natural convection flow: Configuration of a tandem of cold and hot horizontally oriented cylinders placed within a cold cubic enclosure

The study numerically investigated the instability characteristics of a 3D highly separated natural convection flow developing within a cold cubic enclosure in the presence of a tandem of hot and cold horizontally aligned cylinders. The immersed boundary (IB) method was utilized to enforce kinematic no-slip and thermal boundary conditions on the surfaces of the two cylinders. The obtained results were based on the analysis of slightly supercritical flows simulated for three different distances between the cylinders and for Rayleigh numbers Ra∝O(106). It was found that the transition to unsteadiness of the flow sets in via the first Hopf bifurcation, which preserves two types of reflectional symmetry with respect to the central cross-section of the cubic enclosure. The impact of the closeness of the cavity boundaries to the cylinder surfaces on the quantitative and qualitative characteristics of the observed instabilities was extensively investigated. The study elucidated the fundamental instability characteristics typical of highly separated thermally driven flows in confined containers in terms of the bifurcation characteristics and the impact of the object orientation and closeness to the container boundaries on preserving the spatio-temporal symmetries of the slightly supercritical flow.

Temperature Dependences of Mn2+ Photoluminescence with Different Local Surroundings in ZnS Single Crystals

Photoluminescence spectra of Mn2+ in ZnS single crystals were recorded in the range 77–623 K at different activator concentrations and exciting radiation wavelengths. Spectra were decomposed into individual bands, each of which corresponded to radiation of manganese centers with a certain type of local symmetry. The obtained results made it possible to estimate the effect of activator concentration and temperature on changes in the number of radiating manganese centers with different types of local symmetry relative to all luminescent Mn2+ in ZnS single crystals with different excitation wavelengths. The results are explained in terms of the redistribution of direct optical and resonant mechanisms of energy transfer of the exciting light to Mn2+ taking into account losses due to nonradiative interaction with the ZnS single-crystal lattice.

Theoretical study for Coronene and Coronene-Al, B, C, Ga, In and Coronene-O interactions by using Density Functional theory

Molecular structure geometry have been investigated for Coronene and Coronene-Al, B, C, Ga, In and Coronene-O by using Gaussian software at basis set 3-21G, B3LYP level, density functional theory (DFT). Adding the atoms Al, B, C, Ga, In or Oxygen to Coronene change electrons density distribution. Study of the magnetic characterstics shows that some systems like Coronene-Carbon and Coronene-oxygen has the antiferromagnetic charactersti, this type of magnetic properties stands for open shel system which has two type of orbital ? and ? orbitals. Individual atoms calculations was achieved in order to make a comparison between Coronene and the atoms to demonstrate which of them will behave as a donor or an acceptor. EHOMO, ESOMO, ELUMO, total energy electronegativity and electrophilicity were evaluated for all paradigms under the study. Using DFT to study the symmetry shows that there are two types of point group symmetries C6h/C1 and Cs/C1. Coronene-Corbon posseses the highest dipole moment value among the samples, it has the value (5.5873 Debye), dipole moment credit is very important to give sight about the internal structure of substances. Calculations of chemical potential shows clearly Al, Ga and In behave as donors, while B, C and O behave as acceptors. Also binding energy study exhibits that Coronene is going to physisorbe on the surface of the atoms B, C and O.

The Relationship of Symmetry, Complexity, and Shape in Mobile Interface Aesthetics, from an Emotional Perspective—A Case Study of the Smartwatch

Products with interactive interfaces can be seen everywhere, and product interface design aesthetics is a topic that has begun to receive wide attention. Consumers’ perceptions of product interfaces come from their own emotions, and emotion plays a significant role in product interface design aesthetics. In other words, it must meet the users’ emotional and aesthetic requirements. Therefore, we need to better understand the aesthetic design criteria and how they stimulate specific emotional responses. This study takes the dial interface of smartwatches as its experimental sample and explores how the interaction effects of the screen shape (square and round) and the symmetry type and the complexity type of the interface design influence the users’ emotional arousal and valence. In addition, it analyzes the effects of the symmetry type, the complexity type, and the screen shape on the users’ arousal and valence. The results show that the attributes of interface design aesthetics (symmetry-asymmetry, complexity-simplicity, and square-round) affect the users’ emotional responses. Moreover, the interface shape is one of the important factors in the emotional response to an interface design. This paper, based on previous research, provides vital theoretical support for the relevant literature on interface design aesthetics and the users’ emotional state. In addition, it may provide a reference for designers and developers who wish to develop and implement emotional user interfaces that are designed to more effectively appeal to their emotions.

D-dimensional spin projection operators for arbitrary type of symmetry via Brauer algebra idempotents

A new class of representations of the Brauer algebra that centralizes the action of orthogonal and symplectic groups in tensor spaces is found. These representations make it possible to apply the technique of building primitive orthogonal idempotents of the Brauer algebra to the construction of integer spin Behrends–Fronsdal type projectors of an arbitrary type of symmetries.

Modern taxonomy of viruses of vertebrates

The modern taxonomy of viruses of vertebrates is presented according to the information of ICTV issue 07.2019, ratification 03.2020. The leading criteria of taxonomy of viruses are named: type and structure of viral genome, mechanism of replication and morphology of virion. The periods of formation of taxonomic ranks of viruses are characterized: in 1966–1970 genera of viruses were formed, in 1971–1975 – families and subfamilies, since 1990 – orders, in 2018–2019 – realms, kingdoms, phylums, subphylums, classes, suborders, subgenеres. The nomenclature of viruses is described. Viruses belong to the Viruses domain. Viruses of vertebrates (1878 species) belong to 4 realms, 5 kingdoms, 10 phylums, 2 subphylums, 20 classes, 26 orders, 3 suborders, 45 families (of which 15 – DNA-genomic and 30 – RNA-genomic), 33 subfamilies, 345 genera and 49 subgenera. Taxonomic ranks of DNA- and RNA-genomic viruses of vertebrates are described. The DNA-genome family Anelloviridae and the unclassified RNA-genomic genus Deltavirus are not included in any realm. The family Birnaviridae is not classified within the kingdom Orthornavirae. The family of DNA-genomic Hepadnaviridae is included in the realm of RNA-containing viruses Riboviria on the grounds that the replication of hepadnaviruses occurs through the stage of RNA on the principle of reverse transcription, as in the family Retroviridae. The main taxonomic features of DNA- and RNA-genomic viruses of vertebrates are described: type and structure of viral genome (DNA or RNA, number of strands, conformation, fragmentation, polarity), shape and size of virions, presence of outer lipoprotein shell, type of capsid symmetry (spiral, iсosahedral). Some families, in addition to viruses of vertebrates, contain viruses of invertebrates and plants, in particular: families Poxviridae, Iridoviridae, Parvoviridae, Circoviridae, Smacoviridae, Genomoviridae, Rhabdoviridae, Nyamiviridae, Peribunyaviridae, Phenuiviridae, Nairoviviridae, Nodaviridae, Reoviridae and Birnaviridae – viruses of insects; families Genomoviridae, Rhabdoviridae, Phenuiviridae and Reoviridae – viruses of plants; family Nyamiviridae – viruses of nematodes, cestodes, sipunculidеs and echinoderms; family Rhabdoviridae – viruses of nematodes; family Reoviridae – Eriocheir sinensis reovirus; family Birnaviridae – viruses of tellines and rotifers.

Symmetry-Protected Self-Correcting Quantum Memories

A self-correcting quantum memory can store and protect quantum information for a time that increases without bound with the system size and without the need for active error correction. We demonstrate that symmetry can lead to self-correction in 3D spin-lattice models. In particular, we investigate codes given by 2D symmetry-enriched topological (SET) phases that appear naturally on the boundary of 3D symmetry-protected topological (SPT) phases. We find that while conventional on-site symmetries are not sufficient to allow for self-correction in commuting Hamiltonian models of this form, a generalized type of symmetry known as a 1-form symmetry is enough to guarantee self-correction. We illustrate this fact with the 3D "cluster-state" model from the theory of quantum computing. This model is a self-correcting memory, where information is encoded in a 2D SET-ordered phase on the boundary that is protected by the thermally stable SPT ordering of the bulk. We also investigate the gauge color code in this context. Finally, noting that a 1-form symmetry is a very strong constraint, we argue that topologically ordered systems can possess emergent 1-form symmetries, i.e., models where the symmetry appears naturally, without needing to be enforced externally.

Stacking interactions in cavity-containing molecular structures built from acylphloroglucinols: a computational study

Computational studies of cavity-containing molecular structures built from acylphloroglucinol units had shown that the bowl-shaped structures are likely the deepest and most tightly-textured bowls that can be obtained from hydroxybenzenes, and that tube-shaped structures exhibit tight texture with alternatingly higher and lower levels of the benzene rings of the building units. Because of the mutual positions of the aromatic rings in the walls of the cavity, stacking interactions can be expected to play significant roles. The current work presents the results of a computational study in which the previously calculated bowl-shaped and tube-shaped structures were recalculated using the same DFT/B3LYP/6-31 + G(d,p) level of theory, with the inclusion of the Grimme correction to take stacking interactions into account. The energy lowering and the changes in other molecular properties − with respect to the results of calculations without the Grimme correction − are analysed in terms of the shapes of the structures (bowl- or tube-shaped), the number and types of monomeric units constituting it, the symmetry type, and the conformer type. The results confirm the significance of the stacking interactions for cavity-containing structures built from acylphloroglucinols.

Waveguide Modes with Threshold Nonlinearity

A three-layer structure is considered consisting of a nonlinear optical medium with an abrupt change in the dielectric constant, inside which there is a dielectric layer of finite thickness. It is shown that surface waves of two types of symmetry with a special field structure can propagate along the layers. It has been established that in the border regions in a nonlinear medium, regions of finite width with differing optical properties are formed. The formation of such boundary regions, as well as the existence of surface waves, occurs at interlayer thickness not exceeding a certain critical value.

Real and imaginary edge states in stacked Floquet honeycomb lattices

We present a non-Hermitian Floquet model with topological edge states in real and imaginary band gaps. The model utilizes two stacked honeycomb lattices which can be related via four different types of non-Hermitian time-reversal symmetry. Implementing the correct time-reversal symmetry provides us with either two counterpropagating edge states in a real gap, or a single edge state in an imaginary gap. The counterpropagating edge states allow for either helical or chiral transport along the lattice perimeter. In stark contrast, we find that the edge state in the imaginary gap does not propagate. Instead, it remains spatially localized while its amplitude continuously increases. Our model is well-suited for realizing these edge states in photonic waveguide lattices.Graphical abstract

Systematic method for studying single-electron transistors

We present a thorough classification of the electronic transport patterns of single-electron transistors (SETs) using a two-letter notation, based on the symmetry properties of SETs and a nondimensionalization procedure. We find five unique symmetry types of SETs: one symmetric and four asymmetric. For these types and the corresponding dimensionless transistor parameter sets, denoted by the two-letter scheme, we calculate and compare current–voltage curves, modulation curves, charge stability diagrams, and the average and standard deviation of the number of excess electrons on the transistor island. The simulation is performed using the mean of the recurrent solution method for the system of kinetic equations for the charge probability distribution function. On the basis of the simulation results, we analyze the properties of asymmetric SETs. We also consider the effect of asymmetry in the transistor bias voltage and show that this effect can be compensated by renormalization of the left and right junction capacitances. In addition, we propose a measurement technique that can be used to determine the voltage bias asymmetry ratio in real experiments. Finally, using the Bardeen approximation for the tunnel matrix element and the parallel-plate capacitor approximation, we estimate the geometric features of the tunnel junctions.

Effects of L-serine amino acid functionalization on electronic properties of a graphene plane in comparison with oxygen functionalization.

The effects of L-serine amino acid functionalization on a graphene plane were investigated through density functional theory calculations compared with those of oxygen functionalization. Three systems of 4 × 4 graphene supercells were created and functionalized by an epoxy group, a hydroxyl group, and an L-serine molecule. From the geometry optimization of the system containing a 4 × 4 graphene supercell and an L-serine molecule, it was found that a by-product hydroxyl group was formed by the dissociation of the -OH from the parental -COOH group and two covalent bonds forming at a couple of adjacent atoms on the graphene plane. The adsorption energy of the L-serine functionalization was weaker than that of the epoxy functionalization but was stronger than that of the hydroxyl functionalization. Electronic properties of this new L-serine functionalization were similar to epoxy functionalization at low functionalization density, as the Dirac cone was preserved with shifted wave vector due to the double sp3 vacancies. The C2v type of two-fold symmetry was observed through the local density of states (LDOS) and the gamma-point HOMO electron density analysis. However, the improved binding surface area of serine-functionalized graphene was observed, as four polar groups emerged from a single functionalization. Therefore, serine functionalization is a promising way to improve the properties of graphene-based electrodes. Graphical abstract.

Number of equidistant neighbors on honeycomb lattice

A convenient scheme is presented for calculating potential energy of van der Waals interacting bilayer graphene and other similar 2D compounds. It is based on the notion of the existence of two types of local symmetry of carbon atoms ordering, a 3- and 6-fold one. Potential energy of an atom is expressed as a sum of contributions from rings of equidistant atoms on neighboring layer. Methods are described to compute the radius of rings of equidistant atoms and number of atoms they contain. Exact positions of atoms are found as well, allowing to apply the introduced method in modelling of anisotropic potentials and to be used when twisting between layers is present.

СИММЕТРИЯ И АСИММЕТРИЯ СИНТАКСИЧЕСКИХ ПОСТРОЕНИЙ КАК СПОСОБ ПОВЫШЕНИЯ ИНФОРМАЦИОННОЙ ЁМКОСТИ ХУДОЖЕСТВЕННОГО ТЕКСТА

The linguistic object of research is the systemic ties of the plane of text content. The hypothesis of the research is as follows: the principle of repeatability of symmetric and asymmetric elements in the system of semantic and syntactic ties and the relations, demonstrates internal harmony of the text. The harmonious organization of the art text that transfers the esthetic intentions of the author is implemented in the principle of constructing the text as a structural object where the laws of symmetry come to power. Mathematical laws operating the nature provide the source of symmetry as a philosophical category, and the intuitive realization of this idea in the creative spirit of the artist serves as a source of symmetry in art. From numerous types of symmetry in the harmonious organization of the art text employed are figurative and mirror forms of symmetry. The asymmetric constructions, which are characterized by a significant lack of similar and commensurable syntactic patterns within one statement, can also act as a principle of the harmonious organization of the text. They promote the transfer of subjective esthetic information and increase the information capacity of the text. To expressive modifications of the syntactic constructions, functioning in complex syntactic unities (dicteme), belongs parceling structures constructed on the principle of asymmetry. Modeling of the composite structure, in which a certain sequence of structural types of the sentence is fixed, the system of their bonds and the logical relations reduce the entropy of a statement, objectivize the information of such structures and increase the informational capacity of the art text.

Probing Lattice Dynamics and Electronic Resonances in Hexagonal Ge and SixGe1-x Alloys in Nanowires by Raman Spectroscopy.

Recent advances in nanowire synthesis have enabled the realization of crystal phases that in bulk are attainable only under extreme conditions, i.e., high temperature and/or high pressure. For group IV semiconductors this means access to hexagonal-phase SixGe1–x nanostructures (with a 2H type of symmetry), which are predicted to have a direct band gap for x up to 0.5–0.6 and would allow the realization of easily processable optoelectronic devices. Exploiting the quasi-perfect lattice matching between GaAs and Ge, we synthesized hexagonal-phase GaAs-Ge and GaAs-SixGe1–x core–shell nanowires with x up to 0.59. By combining position-, polarization-, and excitation wavelength-dependent μ-Raman spectroscopy studies with first-principles calculations, we explore the full lattice dynamics of these materials. In particular, by obtaining frequency–composition calibration curves for the phonon modes, investigating the dependence of the phononic modes on the position along the nanowire, and exploiting resonant Raman conditions to unveil the coupling between lattice vibrations and electronic transitions, we lay the grounds for a deep understanding of the phononic properties of 2H-SixGe1–x nanostructured alloys and of their relationship with crystal quality, chemical composition, and electronic band structure.

Emulation of spin-orbit coupling for solitons in nonlinear optical media

We design a framework based on the spatial-domain copropagation of two light beams with mutually orthogonal polarizations and opposite transverse components of carrier wave vectors in a nonlinear waveguide with randomly varying birefringence, the averaging with respect to which introduces an effective Manakov nonlinearity in the system. The corresponding two-component system of nonlinear Schr\odinger equations is derived, being similar to the system of coupled one-dimensional Gross-Pitaevskii equations for a binary spin-orbit-coupled Bose-Einstein condensate. The system may also include an effective Rabi coupling (direct linear mixing of the components) and a periodic potential, representing a photonic-crystal structure in the underlying waveguide. For self-focusing and self-defocusing signs of nonlinearity, soliton solutions of several symmetry types are obtained by means of numerical methods, and their stability is investigated, including gap solitons in the case when the periodic potential is present.