Flat Lattice Research Articles

METHODS OF INFLUENCE ON THE SYSTEM TO CHANGE THE ENERGY STATE OF SUBSTANCE: EXPERIENCE, STATE OF THE ISSUE

Methods of influencing the system, the ultimate goal of which is to destruct the natural structure of the material, can be divided as mechanical, physical, chemical, biological and complex. The changing the energy state of a substance is called activation. The current scientific field of ultradispersed materials and physical and chemical processes caused by dispersion is created by the researches of many scientists. Detailed consideration for the increasing reactivity of a solid substance compared to the change in its specific surface area during its mechanical activation showed that the share attributable to the growth of the specific surface area is only a few percent of the mechanical activation effect. The other part is due to the accumulation of defects in the crystals during the grinding process. According to the law of conservation of energy, when a crystal splits, the potential energy of interaction between lattice nodes is transferred to uncompensated surface energy. In addition, the value of the specific surface energy depends on the type of flat lattice used to split the crystal. Therefore, the activation processes and the application of the substance in the active state are relevant in the development of modern binders and concretes. The purpose of the article is to analyse the advantages and disadvantages of the existing methods of influencing the system with the ultimate goal of destruction of the natural structure of the material to changing the energy state of the substance, i.e. its activation. Conclusions. During the destruction of solids, the formation of new cleavage surfaces is accompanied by the breaking of bonds between the substance structural elements and the transition of the potential bond energy into surface energy. Ceteris paribus, the higher the ionic charges and the smaller the distance between them (between adjacent flat grids in the lattice), the greater the value of σ. In addition, the value of the specific surface energy depends on the type of flat grids used to split the crystal. It is worth mentioning that not all methods of activation for binder and concrete (soluble) mixtures are currently implemented on an i industry level. This is due to various reasons. The main method of activation used on an industry level is mechanochemical activation in various types of mills.

SCATTERING OF ELECTROMAGNETIC WAVES ON FLAT GRID TWO-PERIODIC STRUCTURES

Context. One of the scientific hypotheses for the creation of nonreciprocal optical metasurfaces is based on the use of a wave channel in which rays of the direct and reverse diffraction scenarios are realized on two-periodic flat structures with nonlinear elements. Such processes in the nanometer wavelength range of electronic devices require precise calculations of the interaction of waves and microstructures of devices. It is also important to describe the behavior of antenna devices in mobile communications. Expanding the wavelength range of stable communication is achieved by using prefractal structures in antenna devices in combination with periodic structuring. Similar modeling problems arise when electromagnetic waves penetrate materials with a crystalline structure (radio transparency).
 Objective. To test this hypothesis, it is necessary to carry out mathematical modeling of the process of scattering of electromagnetic waves by metasurfaces under conditions of excitation of several diffraction orders. It is known that among two-periodic flat lattices of different structures there are five types that fill the plane. These are the Bravais grilles. The problem of scattering of an incident monochromatic TE polarized wave on a metal screen with recesses in two-periodic structures filled with silicon was considered.
 Method. The paper builds mathematical models for the study of spatial-amplitude spectra of metasurfaces on Brave lattices and gives some results of their numerical study. The condition for determining the diffraction orders propagating over the grating is proposed. Scattered field amplitudes are from the solution of the boundary value problem for the Helmholtz equation in the COMSOL Multiphysics 5.4 package. Similar problem formulations are possible when studying the penetration of an electromagnetic field into a crystalline substance.
 Results. Obtained relations for diffraction orders of electromagnetic waves scattered by a diffraction grating. The existence of wavelengths incident on a two-periodic lattice for which there is no reflected wave is shown for different shapes (rectangular, square, hexagonal) of periodic elements in the center of which a depression filled with silicon was made. Distributions of reflection coefficients for different geometric sizes of colored elements and recesses are given. The characteristics of the electric field at resonant modes in the form of modulus isolines show the nature of the interaction of the field over the periodic lattice and the scatterersdepressions. At the resonant wavelengths of the incident waves, standing waves appear in the scatterers.
 Conclusions. A mathematical model of the set of diffraction orders propagating from a square and hexagonal lattice into halfspace is proposed z >= 0. It has been shown that flat periodic lattice with square or hexagonal periodicity elements and resonant scatterers in the form of cylindrical recesses filled with silicon can produce a non-mirrored scattered field in metal. The response of the lattices to changes in the wavelength of the incident field by the structure of diffraction orders of the scattered field and high sensitivity to the rotation of the incident plane were revealed. The two-periodic lattices have prospects for creating anti-reflective surfaces of various devices. Two-periodic lattices have prospects for creating anti-reflective surfaces for various devices, laser or sensor electronic devices, antennas in mobile communication elements, and radio transparency elements. They have more advanced manufacturing technologies in relation to spatial crystal structures.

On polarization of Smith-Purcell radiation from a photonic crystal slab

We analyze the polarization of radiation arising during the pass of a relativistic electron over a 2D photonic crystal slab consisting of subwavelength particles arranged at the nodes of a flat rectangular lattice. It is shown that the contribution of the parallel and perpendicular polarizations depends on the direction of propagation of the radiation, the bifurcation of the maxima is due to the contribution of the perpendicular polarization, while the asymmetry of the angular distribution is due to the contribution of the parallel polarization.

CLART: A cascaded lattice-and-radical transformer network for Chinese medical named entity recognition

Chinese medical named entity recognition (NER) is a fundamental task in Chinese medical natural language processing, aiming to recognize Chinese medical entities within unstructured medical texts. However, it poses significant challenges mainly due to the extensive usage of medical terms in Chinese medical texts. Although previous studies have made attempts to incorporate lexical or radical knowledge in order to improve the comprehension of medical texts, these studies either focus solely on one of these aspects or utilize a basic concatenation operation to combine these features, which fails to fully utilize the potential of lexical and radical knowledge. In this paper, we propose a novel Cascaded LAttice-and-Radical Transformer (CLART) network to exploit both lexical and radical information for Chinese medical NER. Specifically, given a sentence, a medical lexicon, and a radical dictionary, we first construct a flat lattice (i.e., character-word sequence) for the sentence and radical components of each Chinese character through word matching and radical parsing, respectively. We then employ a lattice Transformer module to capture the dense interactions between characters and matched words, facilitating the enhanced utilization of lexical knowledge. Subsequently, we design a radical Transformer module to model the dense interactions between the lattice and radical features, facilitating better fusion of the lexical and radical knowledge. Finally, we feed the updated lattice-and-radical-aware character representations into a Conditional Random Fields (CRF) decoder to obtain the predicted labels. Experimental results conducted on two publicly available Chinese medical NER datasets show the effectiveness of the proposed method.

HIV-1 immature virion network and icosahedral capsids self-assembly with patchy spheres

The self-assembling process of a simple 3D molecular model that reproduces the hexagonal lattice that HIV-1 has in its immature stage is presented. The system is made of two overlapped repulsive spheres as a building block, both spheres are decorated with attractive patches simulating the main HIV-1 Gag interactions. If the overlapped spheres have the same diameter size, a flat lattice is assembled, while a curvature is induced in the resulting lattice when different diameters are used. Thus, the importance of this model lies on the fact that only by changing the overlapped spheres diameters it is possible to form icosahedral capsids according to the Kaspar and Klug model, known as T = 1, T = 3 and T = 4 without the use of any scaffold, such as the surface of a sphere. Only one molecular species is used to assemble hexagons and pentagons. WCA potential is used for repulsive particles and LJ for the attractive ones. Only two kinds of patches are needed to form a capsid. Two patches to form pairs, which form hexagons and pentagons, and the one that forms triplets, which connects the polygons together. These interactions are based on previous reports of the HIV-1 Gag protein.

Analytical estimation of the natural frequency of vibrations of a flat lattice

A formula is derived for calculating the first natural frequency of vibrations of a statically determined regular lattice with an arbitrary number of panels and masses uniformly distributed over the nodes. Comparison with the minimum frequency from the numerical solution of the problem of the vibration frequency spectrum of the structure shows the high accuracy of the derived assessment. It is shown that for some number of panels, the design allows for kinematic variability. The influence of the lattice attachment method on the natural frequency is studied. Keywords: truss, lattice, vibration frequency, induction, Maple, Dunkerley estimate, attachment method.c216@ya.ru

Curved domain-wall fermion and its anomaly inflow

AbstractWe investigate the effect of a U(1) gauge field on lattice fermion systems with a curved domain-wall mass term. In the same way as the conventional flat domain-wall fermion, the chiral edge modes appear localized at the wall, whose Dirac operator contains the induced gravitational potential as well as the U(1) vector potential. In the case of anS1 domain-wall fermion on a two-dimensional flat lattice, we find a competition between the Aharonov–Bohm(AB) effect and a gravitational gap in the Dirac eigenvalue spectrum, which leads to an anomaly inthe time-reversal (T) symmetry. Our numerical result shows a good consistency with the Atiyah–Patodi–Singer index theorem on a disk inside the S1 domain wall, which describes the cancellation of the T anomaly between the bulk and edge. When the U(1) flux is squeezed inside one plaquette, and the AB phase takes a quantized value π mod $2\pi \mathbb {Z}$, the anomaly inflow drastically changes: the strong flux creates another domain wall around the flux to make the two zero modes coexist. This phenomenon is also observed in the S2 domain-wall fermion in the presence of a magnetic monopole. We find that the domain-wall creation around the monopole microscopically explains the Witten effect.

Pattern formation in nanodomain aggregates of membrane proteins.

Transmembrane proteins, including receptors for growth factors and adhesion, play an important role in cell growth and migration; aberrant spatiotemporal signaling of these membrane proteins may underlie many diseases. Recent studies found that the accurate signaling of these membrane proteins is governed by the nanodomain formations; examples include the formation of synaptic receptor domains and receptor nanodomains encaged in flat clathrin lattice (FCL). However, the underlying physical mechanisms for the formation of such nanodomains still remain unknown. In this work, we compared three different model formulations for nanodomain formation, including 1) deterministic Turing model, 2) stochastic Turing model, and 3) particle-based model, to explore how the biophysics underlying these different models can capture different aspects of nanodomain formation. These nanodomains do not have a large occupancy but are long-term stable, and exhibit changed size and number under extracellular stimulus. Although the deterministic Turing model can generate a stable pattern, it fails to capture the property of changing pattern size and number under stimulus. The stochastic version of Turing model compensates for this shortcoming in the deterministic formulation, but the amount of new nanodomain number is still much less than that observed in the experiment. However, the particle-based model is able to generate more new nanodomains than above Turing models, indicating that the diffusion of each molecule may be driven by a more precise way than the concentration gradient. These findings may shed light on the mechanisms of nanodomain formation of membrane proteins.

Polarized grating transition radiation from a 2D photonic crystal

Transition radiation (TR) is widely used as a radiation source in a wide spectral range, from terahertz to x rays. Conventional flat surfaces are usually used, but with the development of applications using microscopically structured surfaces, periodic surface structures are beginning to be studied. The periodicity of the surface dramatically changes the characteristics of TR, so this type of radiation received its own name: grating transition radiation (GTR). In this work, we investigate the polarization properties of GTR from a two-dimensional (2D) photonic crystal consisting of small particles arranged in a flat lattice (a 2D photonic crystal slab). We show theoretically that the polarization properties of GTR differ significantly from those of the kindred types of radiation: conventional TR and Smith–Purcell radiation. Since we found that the asymptotic behavior depending on the electron velocity for GTR and classical TR diverges, we performed homogenization and show that the results for GTR after homogenization are in perfect agreement with those for classical TR. This means that different dependence on the electron velocity for TR from a slab and for GTR from a 2D photonic crystal slab is caused by the fundamental difference between a conventional slab and a 2D photonic crystal due to its microscopic structure. The constructed theory contains the coordinates of the particles the photonic crystal consists of, which allows considering structures of finite size, both symmetrical and asymmetric. For asymmetric targets, the polarization of the radiation proves to be very sensitive to the electron’s trajectory. This sensibility of polarization characteristics opens up good opportunities for studying fine fundamental effects connected with the electron trajectory, such as the effect of the quantum nature of free electrons which manifests itself in the properties of radiation generated by free electrons. Also, the obtained results may find application in the design of compact sources of polarized radiation based on microscopically structured surfaces.

ЭНЕРГОЭФФЕКТИВНЫЕ ЗДАНИЯ НА ОСНОВЕ ТРАНСФОРМИРУЕМЫХ КАРКАСОВ

. In the construction industry, buildings that provide themselves with energy are increasingly appearing. The article discusses the formative capabilities of the kinematic system, presents lattices and the three-dimensional shapes obtained from them. Special attention is paid to the cylindrical surface, its geometric immutability is ensured by the rigidity of the contour and the spatial shape of the surface of the central part. The authors of the article proposed a public building based on a transformable frame – it is a quick-erect and lightweight spatial structure that will meet the three main requirements of modernity: energy conservation, eco-nomicity and environmental friendliness. Have created a three-dimensional model of the structure, viewed in two states: before construction (flat rectilinear lattice) and after construction. The selection of enclosing structures based on thermal engineering calculations was carried out, and solar panels are used as additional panels. The color scheme of the facades is proposed. The light openings are triangular in shape on the side facade and trapezoidal with triangular at the ends of the building. This solution is due to maintaining the rhythm of structures and sandwich panels. installation of additional internal supports. The absence of internal supports in the building provides freedom in planning issues. To generate an alternative type of energy and save money, solar panels are installed on the building so as not to violate the general concept of facades.

Monte Carlo study of transport in low-dimensional quantum disorder systems at finite temperature

Using the quantum generalized Langevin equation and the path integral Monte Carlo approach, we study the transport dynamics of low-dimensional quantum disorder systems at finite temperature. Motivated by the nature of the classical-to-quantum transformation in fluctuations in the time domain, we extend the treatment to the spatial domain and propose a quantum random-correlated potential, describing specifically quantum disorder. For understanding the Anderson localization from the particle transport perspective, we present an intuitive treatment using a classical analogy in which the particle moves through a flat periodic crystal lattice corrugated by classical or quantum disorder. We emphasize an effective classical disorder potential in studying the quantum effects on the transport dynamics. Compared with the classical case, we find that the quantum escape rate from a disordered metastable potential is larger. Moreover, the diffusion enhancement of a quantum system moving in a weak, biased, periodic disorder potential is more significant compared with the classical case; for an effective rock-ratcheted disorder potential, quantum effects increase the directed current with decreasing temperature. For the classical case, we explore surface diffusion on a two-dimensional biased disorder potential at finite temperature; surprisingly, the optimal angle of the external bias force is found to enhance diffusion in the biased disorder surface. Furthermore, to explain the quantum transport dynamics in a disorder potential, we adopt the barrier-crossing mechanism and the mean first passage time theory to establish the probability distribution function.

Kondo lattice mediated interactions in flat-band systems

Electronic flat bands represent a paradigmatic platform to realize strongly correlated matter due to their associated divergent density of states. In common instances, including electron-electron interactions leads to magnetic instabilities for repulsive interactions and superconductivity for attractive interactions. Nevertheless, interactions of Kondo nature in flat band systems have remained relatively unexplored. Here we address the emergence of interacting states mediated by Kondo lattice coupled to a flat band system. Combining dynamical mean-field theory and tensor networks methods to solve flat band Kondo lattice models in one and two dimensions, we show the emergence of a robust underscreened regime leading to a magnetically ordered state in the flat band. Our results put forward flat band Kondo lattice models as a platform to explore the genuine interplay between flat band physics and many-body Kondo screening.

Crystal structures and continued fractions

In this paper, we consider the properties of a flat crystal structure associated with the matrix representation of finite continued fractions generating unimodular morphisms of a flat integer lattice. The used matrix representations of the continued fractions and their properties are obtained in [1]. The constructed model allows us to explain the existing limitations of the sets of Weiss parameters (the rational ratio of the lengths of the edges of the forming cell) of crystals by the Gauss-Kuzmin distribution of natural numbers in the representation of continued fractions.

Нейронная сеть для определения температуры Кюри двумерной модели Изинга

The authors describe a method for determining the critical point of a second-order phase transitions using a convolutional neural network based on the Ising model on a square lattice. Data for training were obtained using Metropolis algorithm for different temperatures. The neural network was trained on the data corresponding to the low-temperature phase, that is a ferromagnetic one and high-temperature phase, that is a paramagnetic one, respectively. After training, the neural network analyzed input data from the entire temperature range: from 0.1 to 5.0 (in dimensionless units) and determined (the Curie temperature T_c). The accuracy of the obtained results was estimated relative to the Onsager solution for a flat lattice of Ising spins.

Модель графаноподобных соединений h-AB-C: аналитические оценки

In analogy with graphane and fluorographene the model for the compounds h-AB – C, where А and В atoms occupy the sites of the flat hexagonal lattice and С atoms, connected with А and В atoms, are placed by the opposite sides of the АВ-list is proposed. Numerical estimations are fulfilled for the h-A3B5 – C4 compounds, where А, В and С are the atoms from the same row of the Periodic Table. Analytical results are obtained for the electronic spectrum, quantum capacitance, local defect states, force constants and characteristics phonon friquences.

Numerical Implementation of the Inverse Boundary-Value Problem Solution for Hydrodynamic Lattices

One approach to designing turbomachine blades is to use the theory of inverse boundary-value problems of aerohydrodynamics. The basis of the method for solving the inverse problem for a profile lattice located on an axisymmetric stream surface in a layer of variable thickness is the solution of the problem for a flat lattice. In this paper, we consider a number of issues arising in the numerical implementation of the solution of this problem for dense lattices, and we propose methods for solving them and thereby increase the accuracy of numerical calculations.

Two-dimensional FeC compound with square and triangle lattice structure – Molecular dynamics and DFT study

The stability, electronic structure and magnetic behaviors of the two-dimensional (2D) FeC compounds with square and triangle lattice structure are studied by the density functional theory (DFT) calculations. We find that both forms of 2D FeC, one with a flat square lattice structure denoted as t-FeC and another with a puckered triangle lattice structure denoted at tr-FeC, are stable after DFT optimization. However, calculations of the phonon dispersion and binding energy show that the puckered 2D FeC with a triangle lattice structure is the most stable form. We find that both forms of the 2D FeC compounds are metallic and ferromagnetic materials, however, the mean atomic magnetic moment of Fe in the puckered 2D tr-FeC is significantly smaller than that of the flat 2D t-FeC. We check various interatomic potentials for the Fe-C systems implemented in the LAMMPS package and find that only 2D t-FeC can be formed ‘naturally’ from the melt while it does not occur for the 2D tr-FeC. The crystallization temperature (TX≈2600K) and mean interatomic distance for the Fe-C pair of the flat 2D t-FeC have reasonable values. Various structural defects and mechanical behaviors of the flat 2D t-FeC compound are found and discussed.

Linking the Dynamics of Clathrin-Mediated Endocytosis with Membrane Shape Changes in Living Cells with Nanometer Axial Resolution

Clathrin-mediated endocytosis (CME) is essential for cellular homeostasis. Thus, a precise understanding of the biophysical properties of vesicle formation and internalization is necessary. Due to fast dynamics, heterogeneity, and the number of proteins involved in CME, our current knowledge is limited and biased. While fluorescence microscopy provides information about the spatio-temporal dynamics of proteins, it lacks evidence for membrane bending. In contrast, electron microscopy shows membrane curvature, but it lacks dynamic insight. Here, by using Simultaneous Two-wavelength Axial Ratiometry (STAR), we link clathrin dynamics with membrane shape changes. STAR is a TIRF based microscopy technique we developed that takes advantage of the variance in penetration depth generated by different laser wavelengths. By imaging proteins tagged with the EGFP-iRFP fusion (STAR probe), we can generate the ratio of fluorescent intensity and convert it into axial information. The initial transition of plasma membrane from flat to curved and its correlation with clathrin arrival, during endocytosis, remains unclear. We report three different bending dynamics in Cos-7 cells transfected with clathrin light chain STAR probe. Most often clathrin accumulates along with curvature generation, or curvature starts forming shortly before clathrin arrival. Rarely, clathrin first assembles as a flat lattice prior to vesicle formation. Surprisingly, a quarter of de novo clathrin assemblies does not induce curvature. We hypothesize that the flat lattices might be caused by the absence of activated receptors, curvature sensing/inducing proteins, or vesicle maturation markers. To test this and to further describe the difference in initial curvature generation, we are developing a three-color STAR approach to integrate endocytic components with membrane shape changes. In doing so, we hope to unify the physical process of vesicle formation in clathrin-mediated endocytosis with its dynamics.

Growth of graphene on stainless steel by chemical vapor deposition using soybean oil as a carbon source

Graphene is a 2-dimension material which consists of carbon atoms arranged in a flat honeycomb lattice. Graphene has many outstanding properties such as high electron mobility, superb strength, and great flexibility. Although graphene film can be fabricated by economical method such as chemical vapor deposition, the utilization of flammable gas (such as methane, acetylene) in the graphene growth process is still dangerous therefore the safe flammable gas storage and gas line installation are needed. Soybean oil is available vegetable oil which contains carbon, hydrogen and oxygen. Utilization of soybean oil as a carbon source instead of hydrocarbon gas for graphene growth by chemical vapor deposition can avoid an explosion of flammable gas and save the installation cost of gas system. However, the presence of oxygen in soybean oil may obstruct the growth of graphene by chemical vapor deposition. Fortunately, annealing stainless steel with carbon at high temperature can eliminate oxygen from the surface. In this study, the growth of graphene on stainless steel by chemical vapor deposition using soybean oil as a carbon source has been study. The presence and quality of graphene are investigated by Raman spectroscopy. The morphology and element analysis are measured using scanning electron microscope and energy-dispersive X-ray spectroscopy, respectively.

Numerical methods for post-formed timber gridshells: Simulation of the forming process and assessment of R-Funicularity

A nonlinear staged construction analysis is adopted here to simulate the forming process of timber gridshell. In this respect, particular attention is paid to the modelling of the cylindrical joints connecting the orthogonal laths. Cylindrical joints enable the initially flat lattice to be formed into a doubly curved gridshell shape; therefore, accurate modelling of the joints’ mechanical behaviour is a crucial aspect when simulating the forming process of timber gridshells.Another important parameter influencing the gridshell shape is the orientation of laths making up the initially flat lattice. Using an equivalent continuum definition, the final geometry of the gridshells, obtained from different laths orientations, is analysed in here to assess how laths orientation affects the structural shape in terms of funicularity. The Relaxed Funicularity Ellipse method presented in Gabriele et al. (2018) is used for such purpose.