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1,103 results on '"Zhang, Yongxing"'

3. e-basis Coefficients of Chromatic Symmetric Functions

Author

Crew, Logan and Zhang, Yongxing

Subjects
Mathematics - Combinatorics, 05E05, 05C15
Abstract

A well-known result of Stanley's shows that given a graph $G$ with chromatic symmetric function expanded into the basis of elementary symmetric functions as $X_G = \sum c_{\lambda}e_{\lambda}$, the sum of the coefficients $c_{\lambda}$ for $\lambda$ with exactly $k$ parts is equal to the number of acyclic orientations of $G$ with exactly $k$ sinks. However, more is known. The $sink$ $sequence$ of an acyclic orientation of $G$ is a tuple $(s_1,\dots,s_k)$ such that $s_1$ is the number of sinks of the orientation, and recursively each $s_i$ with $i > 1$ is the number of sinks remaining after deleting the sinks contributing to $s_1,\dots,s_{i-1}$. Equivalently, the sink sequence gives the number of vertices at each level of the poset induced by the acyclic orientation. A lesser-known follow-up result of Stanley's determines certain cases in which we can find a sum of $e$-basis coefficients that gives the number of acyclic orientations of $G$ with a given partial sink sequence. Of interest in its own right, this result also admits as a corollary a simple proof of the $e$-positivity of $X_G$ when the stability number of $G$ is $2$. In this paper, we prove a vertex-weighted generalization of this follow-up result, and conjecture a stronger version that admits a similar combinatorial interpretation for a much larger set of $e$-coefficient sums of chromatic symmetric functions. In particular, the conjectured formula would give a combinatorial interpretation for the sum of the coefficients $c_{\lambda}$ with prescribed values of $\lambda_1'$ and $\lambda_2'$ for any unweighted claw-free graph.

Published
2022

14. Hydrodynamic Analysis of High-Speed Vessels in Shallow and Deep Water Using CFD

Author

Budi Utomo, S Samuel, Parlindungan Manik, Chiquita Azaria, Syaiful Tambah Putra Ahmad, and Zhang Yongxing

Subjects
deep water, shallow water, fridsma hull, drag, cfd., Naval Science
Abstract

Differences in the depth of the water surface affect the hydrodynamics of the ship so there is a possibility that the ship will behave differently in deep water and shallow water. The surface flow generated by the hull varies radically due to the speed of the ship and the effects of water depth. At a certain speed, the ship experiences a critical speed condition, which will affect the total resistance of the ship. This study examines the Fridsma ship's resistance to differences in water depth at several speeds. Numerical computation is used in this study to simulate the characteristics of a planing hull form. The Finite Volume Method (FMV) is used to observe fluid flow due to differences in water level with the RANS (Reynolds-Averaged Navier - Stokes) equation in predicting ship resistance. K-ε was modeled as a turbulent and volume of fluid (VOF) model to represent the air and water phases. This study uses a morphing grid mesh to analyze the shape of the hull in numerical simulations. The total resistance of Fridsma in shallow waters increased at each speed when compared to the total resistance in deep waters. On average in deep waters, it can reduce the total resistance by around 22.34% compared to shallow waters. This is caused by the squat phenomenon that occurs in the hull.

Published
2023
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33. Bafi A1 inhibits nano‐copper oxide‐induced mitochondrial damage by reducing the release of copper from lysosomes.

Author

Huang, Zhi, Lin, Mo, Wang, Lei, Dou, Liangding, Hou, Xin, Zhang, Jinwen, Huang, Yongchao, Wei, Lifang, An, Ran, Wang, Dai, Yao, Youliang, Guo, Dongbei, Li, Zhibo, and Zhang, Yongxing

Subjects
LYSOSOMES, COPPER, MITOCHONDRIA, CELL survival, MITOCHONDRIAL proteins, COPPER oxide
Abstract

This study demonstrated that both copper oxide nanoparticles (CuO‐NPs) and copper nanoparticles (Cu‐NPs) can cause swelling, inflammation, and cause damage to the mitochondria of alveolar type II epithelial cells in mice. Cellular examinations indicated that both CuO‐NPs and Cu‐NPs can reduce cell viability and harm the mitochondria of human bronchial epithelial cells, particularly Beas‐2B cells. However, it is clear that CuO‐NPs exhibit a more pronounced detrimental effect compared with Cu‐NPs. Using bafilomycin A1 (Bafi A1), an inhibitor of lysosomal acidification, was found to enhance cell viability and alleviate mitochondrial damage caused by CuO‐NPs. Additionally, Bafi A1 also reduces the accumulation of dihydrolipoamide S‐acetyltransferase (DLAT), a marker for mitochondrial protein toxicity, induced by CuO‐NPs. This observation suggests that the toxicity of CuO‐NPs depends on the distribution of copper particles within cells, a process facilitated by the acidic environment of lysosomes. The release of copper ions is thought to be triggered by the acidic conditions within lysosomes, which aligns with the lysosomal Trojan horse mechanism. However, this association does not seem to be evident with Cu‐NPs. In mice, CuO‐NPs caused more extensive lung tissue damage than Cu‐NPs. In Beas‐2B cells, inhibition of lysosomal acidification with Bafi A1 markedly decreased CuO‐NPs‐induced mitochondrial damage. The lysosomal Trojan horse mechanism of aggravates CuO‐NPs‐induced cuproptosis in Beas‐2B cells, which can be reversed by Bafi A1. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Preparation of Few-Layered MoS 2 by One-Pot Hydrothermal Method for High Supercapacitor Performance.

Author

Jia, Qingling, Wang, Qi, Meng, Lingshuai, Zhao, Yujie, Xu, Jing, Sun, Meng, Li, Zijian, Li, Han, Chen, Huiyu, and Zhang, Yongxing

Subjects
SUPERCAPACITOR performance, ALKALI metal ions, SUPERCAPACITORS, ELECTRON transport, SUPERCAPACITOR electrodes, SODIUM borohydride, MOLYBDENUM disulfide, ALKALI metals
Abstract

Molybdenum disulfide (MoS2), a typical layered material, has important applications in various fields, such as optoelectronics, catalysis, electronic devices, sensors, and supercapacitors. Extensive research has been carried out on few-layered MoS2 in the field of electrochemistry due to its large specific surface area, abundant active sites and short electron transport path. However, the preparation of few-layered MoS2 is a significant challenge. This work presents a simple one-pot hydrothermal method for synthesizing few-layered MoS2. Furthermore, it investigates the exfoliation effect of different amounts of sodium borohydride (NaBH4) as a stripping agent on the layer number of MoS2. Na+ ions, as alkali metal ions, can intercalate between layers to achieve the purpose of exfoliating MoS2. Additionally, NaBH4 exhibits reducibility, which can effectively promote the formation of the metallic phase of MoS2. Few-layered MoS2, as an electrode for supercapacitor, possesses a wide potential window of 0.9 V, and a high specific capacitance of 150 F g−1 at 1 A g−1. This work provides a facile method to prepare few-layered two-dimensional materials for high electrochemical performance. [ABSTRACT FROM AUTHOR]

Published
2024
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