Fast identification of stability of atomically dispersed bi-atom catalysts by a structure descriptor-based model

Atomically dispersed bi-atom catalysts (BACs) exhibit remarkable catalytic performance in a variety of reactions due to the adjacent coordination-unsaturated metal active sites, as well as interatomic synergistic effect. However, high-efficiently...

Texture Representation and Application of Colored Spun Fabric Using Uniform Three-Structure Descriptor

The local binary pattern (LBP) and its variants have shown their effectiveness in texture images representation. However, most of these LBP methods only focus on the histogram of LBP patterns, ignoring the spatial contextual information among them. In this paper, a uniform three-structure descriptor method was proposed by using three different encoding methods so as to obtain the local spatial contextual information for characterizing the nonuniform texture on the surface of colored spun fabrics. The testing results of 180 samples with 18 different color schemes indicate that the established texture representation model can accurately express the nonuniform texture structure of colored spun fabrics. In addition, the overall correlation index between texture features and sample parameters is 0.027 and 0.024, respectively. When compared with the LBP and its variants, the proposed method obtains a higher representational ability, and simultaneously owns a shorter time complexity. At the same time, the algorithm proposed in this paper enjoys ideal effectiveness and universality for fabric image retrieval. The mean Average Precision (mAP) of the first group of samples is 86.2%; in the second group of samples, the mAP of the sample with low twist coefficient is 89.6%, while the mAP of the sample with high twist coefficient is 88.5%.

Some Extremal Graphs with Respect to Sombor Index

Let G be a graph with set of vertices V(G)(|V(G)|=n) and edge set E(G). Very recently, a new degree-based molecular structure descriptor, called Sombor index is denoted by SO(G) and is defined as SO=SO(G)=∑vivj∈E(G)dG(vi)2+dG(vj)2, where dG(vi) is the degree of the vertex vi in G. In this paper we present some lower and upper bounds on the Sombor index of graph G in terms of graph parameters (clique number, chromatic number, number of pendant vertices, etc.) and characterize the extremal graphs.

On Certain Aspects of Topological Indices

A topological index, also known as connectivity index, is a molecular structure descriptor calculated from a molecular graph of a chemical compound which characterizes its topology. Various topological indices are categorized based on their degree, distance, and spectrum. In this study, we calculated and analyzed the degree-based topological indices such as first general Zagreb index M r G , geometric arithmetic index GA G , harmonic index H G , general version of harmonic index H r G , sum connectivity index λ G , general sum connectivity index λ r G , forgotten topological index F G , and many more for the Robertson apex graph. Additionally, we calculated the newly developed topological indices such as the AG 2 G and Sanskruti index for the Robertson apex graph G.

Investigation the effects of cation/anion structure on distribution of Thiophene between IL-rich and Hydrocarbon-rich phases by QSPR approach

Selecting an appropriate ionic liquid as extraction solvent for extracting sulfur compounds from fuel, is a promising way to reduce SOx emissions and to prevent environmental pollution. In this regard, the best structural descriptors of different cation and anion, which play an important role on the thiophene distribution between ionic liquid (IL) and hydrocarbon phases in the ternary systems, that is helpful for selecting a proper IL, have been investigated using quantitative structure − property relationship (QSPR) approach. Five different datasets were collected from the literature containing {(Cation/[NTf2] − thiophene − n-heptane), (Cation/[NTf2] − thiophene − n-hexane), (Cation/[FAP] − thiophene − n-heptane), (Cation/[TCM] − thiophene − n-heptane), ([C2MIM]/Anion − thiophene − hydrocarbon), ([C8MIM]/Anion–thiophene − hydrocarbon)} with 664 data points. By investigating the various kinds of molecular descriptors of 1D, 2D and 3D, it was found that the increment of Spanning Tree Number (STN) descriptor as cation structure descriptor, causes a decrease in mole fraction of thiophene in IL-rich phase due to the increase in steric hindrance. STN descriptor reflects the complexity of structure of cation and the information about steric hindrance. Also, it was found that an increase in E1p value as anion structure descriptor leads to the decrement of mole fraction of thiophene in IL-rich phase, in order to increase the interaction between cation and anion in ionic liquid, that reduced the available space of cation to interact with thiophene. The E1p descriptor represents the density of atoms projected along the length or unfilled space of the anion, thus it is informative of the accessibility of them by thiophene.

Linear Algorithms for the Hosoya Index and Hosoya Matrix of a Tree

The Hosoya index of a graph is defined as the total number of its independent edge sets. This index is an important example of topological indices, a molecular-graph based structure descriptor that is of significant interest in combinatorial chemistry. The Hosoya index inspires the introduction of a matrix associated with a molecular acyclic graph called the Hosoya matrix. We propose a simple linear-time algorithm, which does not require pre-processing, to compute the Hosoya index of an arbitrary tree. A similar approach allows us to show that the Hosoya matrix can be computed in constant time per entry of the matrix.

The (a,b)-Zagreb index of line graphs of subdivision graphs of some molecular structures

A graph is a mathematical model used to predict the topology of a given system. In chemical graph theory, a graph is designed by considering atoms as vertices and edges as bonds between atoms of a particular molecule. A topological index or molecular structure descriptor is a numeric quantity associated with the chemical constitution which correlated with various physiochemical properties of the chemical structure. In this paper, we study the [Formula: see text]-Zagreb index of line graphs of the subdivision graphs of some chemical structures.

Logarithmic Fuzzy Entropy Function for Similarity Measurement in Multimodal Medical Images Registration

Multimodal medical images are useful for observing tissue structure clearly in clinical practice. To integrate multimodal information, multimodal registration is significant. The entropy-based registration applies a structure descriptor set to replace the original multimodal image and compute similarity to express the correlation of images. The accuracy and converging rate of the registration depend on this set. We propose a new method, logarithmic fuzzy entropy function, to compute the descriptor set. It is obvious that the proposed method can increase the upper bound value from log(r) to log(r) + ∆(r) so that a more representative structural descriptor set is formed. The experiment results show that our method has faster converging rate and wider quantified range in multimodal medical images registration.