摘要：
Acoustic phonons have long been believed to dominate the lattice thermal conductivity (kappa l) and the contribution of optical phonons can be neglected in crystal structures. KCaBi, as a high-throughput screening semiconductor with ultralow kappa l [J. Am. Chem. Soc. 144, 4448 (2022)], has been demonstrated that the contribution of optical phonons plays an important role in thermal transport. In this work, by solving the Boltzmann transport equation, it is found that the kappa l of KCaBi is 2.2 at 300K, with acoustic phonons dominating the z-direction kappa l and optical phonons contributing around 50% to the x-direction kappa l under the four-phonon picture. The uncommon contribution of optical phonons also manifests the possibility of tuning the kappa l anisotropy based on optical phonons. Following this line of thinking, it is found that applying tensile strain can cause a more pronounced decrease of acoustic phonon contribution than that of optical counterpart due to the highly dispersive optical branches, thus enhancing the anisotropic ratio of kappa l. Moreover, the microscopic mechanism is elucidated by analyzing the phonon dispersion relation, phonon mode-wise contribution and phonon scattering rates. Our study could provide appealing alternatives for the regulation of phonon transport from the viewpoint of optical phonons.
摘要：
We study wave equations with various spins on the background of a general spherically symmetric spacetime. We obtain the unified expression of the Teukolsky-like master equations and the corresponding radial equations with the general spins. We also discuss the gauge dependence in the gravitational-wave equations, which have appeared in previous studies.
摘要：
We investigate the hydrostatic equilibrium configurations of strange stars within the framework of Rastall-Rainbow theory of gravity. These stars are primarily composed of strange quark matter, with its distribution governed by the color-flavor-locked phase of quark matter equation of state (EoS). Using this EoS, we numerically solve the modified Tolman-Oppenheimer-Volkoff equation to obtain different quark star models. We find that the parameters from this modified gravity have specific contributions to the structure of quark stars and introduce new descriptions for massive celestial bodies. Also, the mass-radius relation strongly depends on the parameters from the considered EoS. Furthermore, we analyze the impact of these parameters on the gravitational redshift and compactness of quark stars.
摘要：
In this paper, we give six classes of permutation polynomials of the form (x(pm) - x + delta)(s) + a(x) over F-2(2m) and six classes of permutation polynomials of the form (x(pm) - x + delta)(s) + ax(pm) + a(pm) x over F-p(2m) (p being an odd prime), respectively. In addition, we also investigate permutation polynomials obtained from piecewise functions. Consequently, we find some complete permutation polynomials.
摘要：
Constitution and distribution of phases and interphase reactions are crucial for properties of composites. So far, the problem of MoS2 agglomeration remains unsolved in Cu/MoS2 composites, and interfacial structures and reaction products between MoS2 and Cu have not been fully considered. Herein, Cu-coated MoS2 powders prepared via electroless plating were sintered at different temperatures into Cu/MoS2 composites. Cu does not react with MoS2 in the composites sintered at 600 ℃ and 650 ℃, leading to their desirable tribological properties under dry sliding. Reactions between Cu and MoS2 occur in the composites sintered at 700 ℃ and 800 ℃, and the resultant products include Cu2S, Cu1.8Mo6S8 and Cu1.83Mo3S4 phases, resulting in a better wear resistance under oil lubrication and mechanical properties.
Constitution and distribution of phases and interphase reactions are crucial for properties of composites. So far, the problem of MoS2 agglomeration remains unsolved in Cu/MoS2 composites, and interfacial structures and reaction products between MoS2 and Cu have not been fully considered. Herein, Cu-coated MoS2 powders prepared via electroless plating were sintered at different temperatures into Cu/MoS2 composites. Cu does not react with MoS2 in the composites sintered at 600 ℃ and 650 ℃, leading to their desirable tribological properties under dry sliding. Reactions between Cu and MoS2 occur in the composites sintered at 700 ℃ and 800 ℃, and the resultant products include Cu2S, Cu1.8Mo6S8 and Cu1.83Mo3S4 phases, resulting in a better wear resistance under oil lubrication and mechanical properties.
期刊：
Qualitative Theory of Dynamical Systems,2024年23(5):1-22 ISSN：1575-5460
通讯作者：
Zhou, M
作者机构：
[Zhou, Mi; Zhou, M] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.;[Zhang, Lu] Xiangtan Univ, Fac Math & Computat Sci, Xiangtan 411105, Hunan, Peoples R China.
通讯机构：
[Zhou, M ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
关键词：
Fractional Langevin equation;Existence;Uniqueness;Fixed point theorem;Stability
摘要：
In this work, we deal with a more general form of fractional Langevin equation. The equation's nonlinearity term f is relevant to fractional integral and fractional derivative. By using the fixed point theorems, we study the existence and uniqueness of solutions of initial value problem for the nonlinear fractional Langevin equation and obtain some new results. Further, by using the technique of nonlinear functional analysis, we study the stability of Ulam-Hyers, Ulam-Hyers-Rassias and semi-Ulam-Hyers-Rassias for the initial value problem of nonlinear Langevin equation. Finally, some examples are given to show the effectiveness of theoretical results.
通讯机构：
[Xu, BM ; Wang, XZ] S;[Wang, XZ ] U;Southern Univ Sci & Technol, Dept Mat Sci & Engn, Shenzhen 518055, Peoples R China.;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;Southern Univ Sci & Technol, Shenzhen Engn Res & Dev Ctr Flexible Solar Cells, Shenzhen 518055, Peoples R China.
摘要：
As the most promising lead-free perovskite, tin-based perovskite has attracted much attention due to its suitable bandgap and low toxicity. However, many defects (tin vacancy defects caused by Sn2+ oxidation to Sn4+, grain boundary defects and point defects) in tin-based perovskite lead to serious losses in device efficiency. Here, a universal and effective doping strategy is delivered to improve the structure and optoelectronic properties of tin-based perovskite films through 2,8-dibromo-dibenzothiophene-S,S-dioxide (BrDS) doping. The introduction of BrDS can effectively inhibit the oxidation of Sn2+ and passivate grain boundary defects and point defects in the perovskite films. The tin-based perovskite film doped with BrDS exhibits higher carrier lifetime and crystal quality. As a result, the BrDS-doped device achieves a power conversion efficiency of 14.98% with a certified efficiency of 14.36%, which is one of the highest PCEs among all values reported to date for tin-based PSCs. In addition, the BrDS-doped PSC devices exhibit significantly improved long-term stability and improved operational stability in a N-2 atmosphere. This work represents a noteworthy step towards manufacturing efficient and stable tin-based PSCs.
摘要：
Let q = 2(m). In this paper, we investigate permutation pentanomials over F-q(2) of the form f(x) = x(t) + x(1)(r)(q-1)+t + x(2)(r)(q-1)+t + x(3)(r)(q-1)+t + x(4)(r)(q-1)+t with gcd(x(4)(r) + x(3)(r) + x(2)(r) + x(1)(r) + 1, xt + x(1)(t-r) + x(2)(t-r)+ x(</span>)(t-r) + x(4)(t-r) ) = 1. We transform the problem concerning permutation property of f(x) into demonstrating that the corresponding fractional polynomial permutes the unit circle U of F-q(2) with order q + 1 via a well-known lemma, and then into showing that there are no certain solution in F-q for some highdegree equations over F-q associated with the fractional polynomial. According to numerical data, we have found all such permutations with 4 <= t < 100, 1 <= r(i )< t, i is an element of [1, 4]. Several permutation polynomials are also investigated from the fractional polynomials permuting the unit circle U found in this paper. (c) 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar
期刊：
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS,2024年2024(2):046 ISSN：1475-7516
作者机构：
[Nakajima, Hiroaki] School of Mathematics and Physics, University of South China, Hengyang, 421001, China;School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, 610031, China;[Guo, Ya; Lin, Wenbin] School of Mathematics and Physics, University of South China, Hengyang, 421001, China<&wdkj&>School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, 610031, China
摘要：
Recently, CdX (X = Se, Te) materials have garnered notable interest owing to their great application potential for high-efficiency solar cells, fiber optic communication systems, and nanoelectronic devices. The performance of optoelectric devices is significantly influenced by the thermal conductivity. In this study, a combination of machine-learning methods and first-principles calculations is utilized to investigate the phonon thermal transport properties of CdSe and CdTe, as well as to give deep insights into the phonon behavior in heat transfer. It is found that acoustic phonons dominate the lattice thermal conductivity (lc) in CdSe, while optical phonons contribute around 50 % to the lc value in CdTe. There are strikingly strong four-phonon scattering phenomena in both materials, which result in 55 % and 66 % reduction in lc values for CdSe and CdTe, respectively. Further analysis shows that the mid-frequency phonons play an important role in amplifying the four-phonon scattering. Its special frequency positions permit an unusually large number of four-phonon scattering processes to occur and cause large scattering of low-frequency phonons. This mechanism differs from earlier proposed features regarding large acoustic-optical gaps, bunching of acoustic branches and four-phonon Fermi resonance, which implies strong four-phonon anharmonicity. Thus, the present work opens up new prospects in the exploration and design of innovative thermoelectric material, which provides a more thorough understanding of the fourphonon scattering mechanisms in crystalline solids.
摘要：
Abstract: A generalized scheme of chaos synchronization, which is called multiple function projective synchronization, is first reported in this paper. This synchronization scheme is more generalized than many existing ones. Under the scheme, the synchronous behavior between two synchronized systems is more complicated. By utilizing the proposed synchronization scheme and introducing the parameter perturbation factor, a novel algorithm of secure communication is designed. From theoretical analysis and numerical simulations, the validity and feasibility of this algorithm is proved. Finally, some discussions and comparison experiments are established to illuminate the security of this algorithm.#@#@#摘要: 本文提出了一种新的混沌同步方案——多重函数投影同步，该同步方案比许多现有同步方案更加广义，两个同步系统之间的同步行为更加复杂。基于所提的同步方案并引入参数扰动因子，设计了一种新的保密通信算法，并通过理论分析和数值模拟，证实了算法的有效性和可行性。最后，通过讨论和对比实验展示了该算法的安全性。
期刊：
Fuzzy Sets and Systems,2024年479:108856 ISSN：0165-0114
通讯作者：
Liu, HL
作者机构：
[Xiao, Qizhen; Liu, Hongliang; Liu, HL; Luo, Zhiyong] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Xiao, Qizhen; Liu, Hongliang; Liu, HL] Univ South China, Hunan Key Lab Math Modeling & Sci Comp, Hengyang 421001, Peoples R China.
通讯机构：
[Liu, HL ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;Univ South China, Hunan Key Lab Math Modeling & Sci Comp, Hengyang 421001, Peoples R China.
关键词：
Aperiodic DoS attacks;Resilient synchronization;Fixed-time stability;Fuzzy neural networks;Reaction-diffusion terms
摘要：
This work focuses on the resilient fixed -time synchronization of delayed fuzzy memristive reaction -diffusion neural networks under denial -of -service (DoS) attacks. To efficaciously tolerate the aperiodic DoS attacks, a new appropriate controller is designed to ensure the fixed -time resilient synchronization of the systems. Moreover, two mild sufficient conditions are first proposed and the constrained techniques of attacking intervals are employed to overcome the challenge of estimating the upper bound of the settling time under aperiodic DoS attacks. Lastly, an example is utilized to illustrate the effectiveness and feasibility of the theoretical result.
摘要：
We present an atomistic simulation of thermoelectric properties in cove-edged graphene nanoribbons (CGNRs) via the nonequilibrium Green's function. Different from gapless zigzag graphene nanoribbons (ZGNRs), CGNRs exhibit a noticeable bandgap. Such a bandgap can be modulated by varying three structural parameters (namely, the width N, the distance between adjacent coves m, as well as the shortest offset n) of CGNRs, which can give rise to the transition from semiconducting to semi-metallic. Due to the less dispersive phonon bands and the decrease in the number of phonon channels of CGNRs, they are found to have the lower phonon thermal conductance than ZGNRs. Modulation of CGNRs can produce over tenfold improvement of the maximum of ZT compared to ZGNRs. This improvement is due to the promotion of the Seebeck coefficient together with the degradation of the phonon thermal conductance of CGNRs compared to ZGNRs.
作者机构：
[Wang, Xingzhu; Wang, XZ; Chen, Jinbo; Zhou, Xianyong; Liu, Chang] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Wang, Xingzhu; Chen, Jinbo; Zhou, Xianyong; Liu, Chang] Univ South China, Engn & Res Ctr Integrated New Energy Photovolta &, Hengyang 421001, Peoples R China.;[Wu, Jiawen; Wang, Xingzhu; Liu, Zhixin; Wang, Deng; Peng, Wenbo; Xu, Baomin; Zhou, Xianyong; Zeng, Jie; Liu, Chang; Zhang, Yong] Creat & Renewable New Energy Co, Hengyang 421001, Peoples R China.;[Xu, Baomin; Wu, Jiawen; Wang, Xingzhu; Liu, Zhixin; Wang, Deng; Wang, XZ; Peng, Wenbo; Zhou, Xianyong; Zeng, Jie; Zhang, Yong] Southern Univ Sci & Technol, Dept Mat Sci & Engn, Shenzhen 518055, Peoples R China.;[Wu, Jiawen; Wang, Xingzhu; Liu, Zhixin; Wang, Deng; Peng, Wenbo; Xu, Baomin; Zhou, Xianyong; Zeng, Jie; Zhang, Yong] Southern Univ Sci & Technol, Shenzhen Engn Res & Dev Ctr Flexible Solar Cells, Shenzhen 518055, Peoples R China.
通讯机构：
[Xu, BM ; Wang, XZ] S;[Wang, XZ ; Liu, C] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;Southern Univ Sci & Technol, Dept Mat Sci & Engn, Shenzhen 518055, Peoples R China.
关键词：
Inverted perovskite solar cells;Power conversion efficiency;Efficient and stable;Buried interface engineering
摘要：
buried interfaces are crucial for achieving efficient and stable perovskite solar cells (PSCs). However, studying and optimizing buried interfaces remains a challenging issue due to its non-exposed characteristics. Here, a simple and effective targeting strategy is proposed to regulate the NiOx/perovskite buried interface by passivating buried defects in perovskite and adjusting the growth of perovskite crystals through modifying multifunctional molecules (DTD) on the surface of NiOx. DTD has multifunctional targeting groups that enable it to interact strongly with both perovskite and NiOx simultaneously, thereby building a molecular bridge at the NiOx/perovskite buried interface, enabling high-quality upper perovskite films, excellent interface contact and more matched energy levels between perovskite and NiOx. As a result, the modification of DTD significantly improves the efficiency of perovskite devices from 22.19 % to 25.00 % (certified value of 24.12 %), along with excellent long-term and operational stability. This strategy provides a simple and effective targeted therapy for the buried interface in PSC, achieving high efficiency and stability.
摘要：
Despite the recognized potential of two-dimensional crystals in organic photovoltaics (OPVs), a comprehensive understanding of layer-dependent doping effects remains elusive. Here, we employed liquid-phase exfoliation to synthesize various layers of novel metal phosphorus tri-chalcogenide (TMPTC), Cd0.85PS3Li0.15H0.15. Molecular dynamics simulation shows that Cd0.85PS3Li0.15H0.15 tends to be distributed in the domain of D18. Although increasing the Cd0.85PS3Li0.15H0.15 layer can improve its ability to adsorb D18, it will also form a larger steric hindrance in the domain of D18. The 2L Cd0.85PS3Li0.15H0.15 has balanced adsorption capacity and steric hindrance, maximally inducing the crystallinity of D18, thus significantly promoting the charge transport and effectively suppressing the bulk charge recombination in D18:L8-BO devices. Consequently, the power conversion efficiency (PCE) of D18:L8-BO-based OPVs experienced a significant boost from 17.57 % to 19.59 %. In addition, the Cd0.85PS3Li0.15H0.15 dopants can enhance the nuclear radiation shielding ability of OPVs, which can provide the theoretical and experimental basis for developing two-dimensional TMPTCs dopants toward OPVs with nuclear radiation shielding.
期刊：
Finite Fields and Their Applications,2024年94:102354 ISSN：1071-5797
通讯作者：
Kan, HB
作者机构：
[Zheng, Lijing] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.;[Kan, Haibin] Fudan Univ, Sch Comp Sci, Shanghai Key Lab Intelligent Informat Proc, Shanghai 200433, Peoples R China.;[Kan, Haibin] Shanghai Engn Res Ctr Blockchain, Shanghai 200433, Peoples R China.;[Kan, Haibin] Fudan Univ, Yiwu Res Inst, Yiwu City 322000, Peoples R China.;[Zhang, Tongliang] North China Univ Sci & Technol, Coll Sci, Tangshan 063000, Hebei, Peoples R China.
通讯机构：
[Kan, HB ] F;Fudan Univ, Sch Comp Sci, Shanghai Key Lab Intelligent Informat Proc, Shanghai 200433, Peoples R China.;Shanghai Engn Res Ctr Blockchain, Shanghai 200433, Peoples R China.;Fudan Univ, Yiwu Res Inst, Yiwu City 322000, Peoples R China.
关键词：
Finite field;Permutation trinomial
摘要：
Let q = 2m and Fq3 be the finite field with q3 elements. In this paper, based on the multivariate method, resultant elimination, and transforming into dealing with some equations over finite fields, we propose two classes of permutation trinomials of Fq3. We illustrate that these two classes of permutation trinomials are QM-inequivalent to all known permutation polynomials over Fq3. Some well-known results can be covered by our theorems.(c) 2023 Elsevier Inc. All rights reserved.
摘要：
Mining can provide abundant resources, but it also causes heavy metal wastewater pollution, which poses a serious threat to aquatic ecosystems. In this study, Cypridopsis vidua was used as the test organism to investigate the single and combined acute toxicity of common heavy metals (such as chromium (Cr) and nickel (Ni)) in mining wastewater. Then, a random forest model (RF model) was used to predict the combined toxicity of chromium and nickel. Single acute toxicity experiments showed that the 96 h-LC(50 )values of the Cr and Ni for Cypridopsis vidua were 0.81 mg/L and 4.3 mg/L, respectively. aCr was more toxic than Ni. Furthermore, the combined acute toxicity experiments demonstrated that the toxicity of Cr-Ni was higher than Ni but lower than Cr. The predicted results of the RF model were highly consistent with the experimental results of the Cr-Ni combined acute toxicity. So, the model has accurate toxicity prediction ability.
摘要：
In this paper, we construct three classes of permutation quadrinomials with Niho exponents of the form
$$f(x)=\alpha _0x^r+\alpha _1x^{s_1(p^m-1)+r}+\alpha _2x^{s_2(p^m-1)+r}+\alpha _3x^{s_3(p^m-1)+r}\in \mathbb {F}_{p^{n}}[x]$$
, where p is an odd prime,
$$n=2m $$
is a positive even integer, and
$$(r,s_1,s_2,s_3)=(1,\frac{-1}{p^k-2},1,\frac{p^k-1}{p^k-2})$$
,
$$(1,\frac{p^k+1}{p^k+2},1,\frac{1}{p^k+2})$$
and (3, 1, 2, 3), respectively. The exponents of the first two classes are considered for the first time, and the third class covers all the permutation polynomials proposed by Gupta (Designs Codes and Cryptography 88, 1–17, 2020).
