摘要：
An eco-friendly,sustainable and practical method for the efficient preparation of 5-organylselanyl uracils through the electrochemical selenylation of uracils and dio rganyl diselenides at room temperature under oxidant-and external electrolvte-free conditions was developed.
摘要：
Developing a reliable fluorescence probe is crucial for accurately monitoring sodium dithionite (Na2S2O4, SDT) in biosystems, but the current reported azo-based ones suffers from short excitation/emission wavelengths and relative slow response speed. To address this issue, we herein present a novel near-infrared emissive fluorescence probe for SDT, namely DCM-MQ, consisting of a dicyanomethylene-benzopyran fluorogenic reporter and a 1-methylquinolinium as recognition moiety. On the basis of the specific reduction mechanism, DCM-MQ exhibited a rapid colorimetric and fluorescent recognition for SDT (less than 3 s) with large Stokes shift (112 nm) and high sensitivity (detection limit was 19 nM). The fluorescence imaging results demonstrate that DCM-MQ is competent for monitoring SDT in living systems. (C) 2020 Elsevier B.V. All rights reserved.
作者机构：
[Xiong, Pei-Ying] Hunan City Univ, Sch Sci, Yiyang 413000, Peoples R China.;[Jahanshahi, Hadi] Univ Manitoba, Dept Mech Engn, Winnipeg, MB R3T 5V6, Canada.;[Alcaraz, Raul] Univ Castilla La Mancha UCLM, Res Grp Elect Biomed & Telecommun Engn, Cuenca 16071, Spain.;[Chu, Yu-Ming] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.;[Chu, Yu-Ming] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Peoples R China.
通讯机构：
[Yu-Ming Chu] D;[J.F. Gómez-Aguilar] C;CONACyT-Tecnológico Nacional de México/CENIDET. Interior Internado Palmira S/N, Col. Palmira, C.P. 62490, Cuernavaca, Morelos, México<&wdkj&>Universidad Tecnológica de México – UNITEC MÉXICO – Campus En Línea<&wdkj&>Department of Mathematics, Huzhou University, Huzhou 313000, P. R. China<&wdkj&>Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science & Technology, Changsha 410114, P. R. China
关键词：
Chaos;Fractional calculus;Hidden attractors;Self-excited system;Robust control;Intelligent control technique;Disturbance observer
摘要：
An immense body of research has focused on chaotic systems, mainly because of their interesting applications in a wide variety of fields. A comprehensive understanding and synchronization of chaotic systems play pivotal roles in practical applications. To this end, the present study investigates a multi stable fractional-order chaotic system. Firstly, some dynamical features of the system are described, and the chaotic behaviour of the system is verified. Then, both spectral entropy and spectral Min-Entropy are computed, and the phenomenon of multi-stability is shown. Besides, the combination of a new chattering-free robust sliding mode controller with a neural network observer is proposed for the synchronization of the fractional-order system. With the neural network estimator, unknown functions of the system are obtained, and the effects of disturbances are completely taken into account. Also, based on the Lyapunov stability theorem, the asymptotical stability of the closed-loop system is confirmed. Lastly, the proposed control technique is applied to the fractional-order system. Numerical results demonstrate the chattering-free and effective performance of the proposed control method for uncertain systems in the presence of unknown time-varying external disturbances. (c) 2021 Elsevier Ltd. All rights reserved.
通讯机构：
[Dai, Zhifeng] C;Changsha Univ Sci & Technol, Coll Math & Stat, Changsha 410114, Peoples R China.
关键词：
New technical indicators;De-noise;In-sample forecast;Out-of-sample forecast;Economic significance
摘要：
We find that combining de-noising stock returns by wavelet transform with new proposed technical indicators can significantly improve the accuracy of stock returns forecasts, in which the new technical indicators can directly reflect the trend of stock returns series. Empirical results indicate the stock returns forecasts generated by new technical indicators are statistically and economically significant both in-sample and out-of-sample prediction performance. And when multivariate information is used to predict stock returns, its predictability is also significant. In addition, it is robust for the prediction performance of new indicators using some extension and robustness analysis.
作者：
Wang, Tong;Almarashi, Adel;Al-Turki, Yusuf A.;Abu-Hamdeh, Nidal H.;Hajizadeh, Mohammed Reza;...
期刊：
Journal of Molecular Liquids,2021年329:115052 ISSN：0167-7322
通讯作者：
Yu-Ming Chu
作者机构：
[Wang, Tong] Huazhong Univ Sci & Technol, Sch Architecture & Urban Planning, Dept Landscape Architecture, Wuhan, Hubei, Peoples R China.;[Almarashi, Adel] Jazan Univ, Coll Sci, Dept Math, Post Box 2097,New Campus, Jazan, Saudi Arabia.;[Al-Turki, Yusuf A.; Abu-Hamdeh, Nidal H.] King Abdulaziz Univ, Fac Engn, Ctr Res Excellence Renewable Energy & Power Syst, Jeddah 21589, Saudi Arabia.;[Al-Turki, Yusuf A.] King Abdulaziz Univ, Fac Engn, Dept Elect & Comp Engn, Jeddah 21589, Saudi Arabia.;[Abu-Hamdeh, Nidal H.] King Abdulaziz Univ, Fac Engn, Dept Mech Engn, Jeddah 21589, Saudi Arabia.
通讯机构：
[Yu-Ming Chu] D;Department of Mathematics, Huzhou University, Huzhou 313000, China<&wdkj&>Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science & Technology, Changsha 410114, China
关键词：
Nanomaterial;Heat release;Galerkin approach;Wavy tank;Radial fins
摘要：
In this research, sinusoidal tank including inner circular cylinder was considered and to expedite the solidification, radial fins were installed over the inner cold cylinder. To improve the conduction, CuO nano sized material was added and effects of size of particles were involved. The governing equations consist of energy equation with one source term of solid fraction and equation for distribution of ice fraction. To fins the solution, Galerkin approach was applied and different mesh configuration in various time step helps to capture the phenomena more accurate. Validation with experimental data shows the nice accommodation. So, influence of fins length and diameter of particles were imposed. As longer fins were employed, the solidification time reduces about 3.74% when d(p) = 40. As d(p) rises from 40 to 50, temperature augments and greater energy has been achieved because of augmentation of needed time from 175.44 to 264.05 s. Impact of dp on isotherms is more significant than fins length. (C) 2020 Elsevier B.V. All rights reserved.
作者机构：
[Ibrahim, Muhammad] Univ Sci & Technol Beijing, Sch Math & Phys, Beijing 100083, Peoples R China.;[Saeed, Tareq] King Abdulaziz Univ, Fac Sci, Dept Math, Nonlinear Anal & Appl Math NAAM Res Grp, POB 80203, Jeddah 21589, Saudi Arabia.;[Chu, Yu-Ming] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.;[Chu, Yu-Ming] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Peoples R China.;[Ali, Hafiz Muhammad] King Fand Univ Petr & Minerals, Mech Engn Dept, Dhahran 31261, Saudi Arabia.
通讯机构：
[Yu-Ming Chu] D;Department of Mathematics, Huzhou University, Huzhou 313000, PR China<&wdkj&>Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
摘要：
In this study, thermal conductivity of graphene nano-sheets (GNs)/ethylene glycol (EG) nanofluidwas compared with EG thermal conductivity at 25-70 degrees C and 0.005-0.5 wt% to examine the effects of GNs nanoparticles. For all samples, presence of nanoparticles intensifies EG thermal conductivity up to 54.6%. Moreover, loading GNs into EG inverts the dependency of the thermal conductivity to temperature. As the temperature rises, the thermal conductivity of the base fluid decreases, while for nanofluid, thermal conductivity increases. Based on the results, by incorporating more nanoparticles, the positive effects of nanoparticles on thermal conductivity s reduced. It was concluded that with increasing temperature, the effect of adding GNs on the thermal conductivity is strengthened. Neural network implementation showed that this method can forecast k(GNs)/EC/k(EG) with maximum error of less than 3%. (C) 2021 Elsevier B.V. All rights reserved.
作者机构：
[Khan, M. Ijaz] Riphah Int Univ, Dept Math, Faisalabad Campus, Faisalabad 38000, Pakistan.;[Kadry, Seifedine] Beirut Arab Univ, Dept Math & Comp Sci, Beirut, Lebanon.;[Chu, Yuming] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.;[Chu, Yuming] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Peoples R China.;[Waqas, M.] Natl Univ Technol, NUTECH Sch Appl Sci & Humanities, Islamabad 44000, Pakistan.
通讯机构：
[Yuming Chu] D;Department of Mathematics, Huzhou University, Huzhou 313000, China<&wdkj&>Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science & Technology, Changsha 410114, China
关键词：
Activation energy;Convective boundary condition;Darcy–Forchheimer porous medium;Heat generation/absorption;Second order velocity slip;Titanium dioxide and graphene oxide nanoparticles
摘要：
Studies associated with dynamic plate–medium interactions generally assumed the plate structures to be permeable for the sake of convenience. But the effect and applicability of such an assumption are still unclear, and then the pore fluid pressure on the plate and medium interfaces cannot be obtained. In this paper, the mentioned problems are discussed by studying the coupling steady-state vibration of an impermeable, rigid, circular plate resting on a finite, fluid-saturated, poroelastic soil layer underlain by rigid base and subjected to a vertical time-harmonic loading. The semi-analytical solutions for the dynamic compliance, displacements, stresses, especially the contact stress including effective stress and pore fluid pressure of the plate and the layer, are proposed. In developing these solutions, the linearly poroelastic model established by de Boer is used to describe the mechanical behaviour of the porous medium. By means of four scalar displacement potentials and the Fourier–Hankel transformation to solve the equations of motion of the poroelastic layer, and then imposing boundary and interfacial conditions, a pair of coupling Fredholm’s integral equations of the second kind formulating the plate–medium interaction are derived and evaluated with numerical methods. The proposed solutions are then verified by comparing with the existing special solutions and the FEM calculation results. Numerical examples are also performed to examine the effects of the permeability of both the plate and the poroelastic layer and the thickness of the layer on the dynamic response of the coupling system.
关键词：
Dangerous driving behavior;cause of accident;individual characteristics of the driver;real-world traffic accident data;evaluation model
摘要：
This paper constructs an evaluation system that reflects dangerous driving behavior. The evaluation system has a three-layer structure model of "Evaluation Index-Performance Mode-Driving behavior score." Verification of the feasibility of the model based on the relationship between the driver and the cause of the accident based on behavioral characteristics. First, the driving return survey data and accident form information of the real traffic accident cases of China In-Depth Accident Study (CIDAS) database are counted, and the character variables are converted into digital variables. Then, a three-tier structure of the dangerous driving behavior evaluation system is built, and the correlation between the driver and the cause of the accident is conducted to verify the feasibility of the model. The research shows that the individual characteristics of drivers with dangerous driving behavior are closely related to the cause of accidents, and the evaluation system constructed in this paper can quantify and describe this relationship effectively.
摘要：
As a primary building block for protein synthesis, L-arginine (L-Arg) is also a precursor for the synthesis of important metabolites, and is involved in various physiological and pathophysiological processes. L-Arg is a potential biomarker in clinical diagnosis and nutritional status assessment, making it valuable to quantify and monitor this biomolecule. In this study, peptide aptamers that specifically interact with L-Arg were identified by high-throughput molecular docking, and the binding capacities between the synthesized peptide aptamers and L-Arg were then measured by isothermal titration calorimetry. We hypothesized that the peptide aptamer with the greatest binding capacity could be used as the recognition element in a biosensor. A chemosynthetic peptide aptamer modified with mercaptan and spacer units (thioctic acid-GGGG-FGHIHEGY) was thus used to construct label-free electrochemical impedimetric biosensors for L-Arg based on gold electrodes. The optimum biosensor showed good sensitivity to L-Arg with a linear range of 0.1 pM-0.1 mM, and the calculated limit of detection (three times the signal-to-noise ratio) was 0.01 pM. Interference studies and assays of diluted serum samples were also carried out, and satisfactory results obtained. In conclusion, a potential method of peptide aptamer screening and biosensor fabrication for detecting small biological molecules was demonstrated. (C) 2020 Elsevier B.V. All rights reserved.
作者机构：
[Waqas, Hassan; Farooq, Umar] Govt Coll Univ Faisalabad, Dept Math, Layyah Campus, Faisalabad 31200, Pakistan.;[Khan, M. Ijaz] Riphah Int Univ, Dept Math & Stat, I-14, Islamabad 44000, Pakistan.;[Khan, Sami Ullah] COMSATS Univ Islamabad, Dept Math, Sahiwal 57000, Pakistan.;[Chu, Yu-Ming] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.;[Chu, Yu-Ming] Changsha Univ Sci & Technol, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Peoples R China.
通讯机构：
[Yu-Ming Chu] D;Department of Mathematics, Huzhou University, Huzhou 313000, PR China<&wdkj&>Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science & Technology, Changsha 410114, PR China
摘要：
The nanoparticles proved a motivating research area in the fourth generation of the world due to their extensive use in science and infrastructure, such as vehicle cooling, higher heat transfer rates in microchips, food manufacturing, biotechnology, biochemistry, transportation, metrology and nuclear reactors. Dispersing the nanoparticles within base fluid is a newly approach for implementations of heat transfer and biomedicine/bioengineering. The current determination is committed to explore the features of bioconvection in Carreau nanofluid flow under the influence of various thermal consequences. The flow is originated by a stretched cylinder. The characteristics of Cattaneo-Christov heat and mass flux are applied to examine the heat/mass transportation of nano fluid. The effects of thermal radiation and activation energy are also considered. The consequences of Brownian movement and thermophoresis features are analyzed by incorporating Buongiorno's nanofluid model. The governing partial differential equations are transmuted into the structure of nonlinear ordinary differential equations by introducing suitable transformation. The shooting technique is used to achieve the numerical simulations of nonlinear system. The physical impacts of prominent parameters on velocity, temperature distribution, concentration field and microorganisms profile are examined and captured graphically. The numerical outcomes against various flow quantities are also presented in tabular form. The results convey that a higher temperature profile is observed with larger values of thermal Biot number, exponential base sink parameter and thermal relaxation parameter while a decrement in temperature is noticed with increasing mixed convection parameter. The concentration profile shows an increasing trend with mass concentration parameter and concentration relaxation parameter. Moreover, the microorganism field decline with Peclet number and bioconvection Lewis number. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
摘要：
The most common primary damage form of rubber asphalt pavements is fatigue cracking. At present, the indirect tension, direct tension, bending, and unconfined compression tests are the main considered fatigue parameters to design the structure of rubber asphalt pavement. However, the fatigue test results analyzed by various test methods have a quite significant divergence, which represents a lack of accuracy to access the durability of rubber asphalt mixture objectively. Thus, in the structural resistance design of rubber asphalt pavement, there exists a problem of artificial randomness of fatigue parameters. Hence, the primary objective of this study is to improve the procedure for determining the structural resistance of rubber asphalt pavement. To this end, the direct tensile, unconfined compressive, and indirect tensile strength tests of rubber asphalt mixture were performed under various loading rates to reveal the velocity-dependent of the strength of rubber asphalt mixture. The model of direct tensile strength, unconfined compressive strength, and indirect tensile strength increasing with loading rate are S-D = 7.772v(0.205), S-C = 1.748v(0.204), and S-T = 1.077v(0.207), respectively. The stress ratio related to both the traditional SeN fatigue equation and the loading rate was defined as the standard stress ratio and the velocity-dependent stress ratio, respectively. The fatigue test of rubber asphalt mixture was conducted. The results from those experiments were analyzed. A fatigue equation (N-f = t(v)(-5.129) R-2 = 0.853) related to the loading rate was established. The results indicated that the viscoelastic characteristics of rubber asphalt mixture are not taken into consideration in the traditional SeN fatigue equation, which contributed to the non-uniqueness and uncertainty of fatigue test results. The viscoelastic characteristics of rubber asphalt mixture are considered by the fatigue equation related to the velocity-dependent stress ratio. Thus, a new method (K-v = N-f(0.0958)) considering the influence of the loading rate for calculating the strength structure coefficient of the rubber asphalt mixture was proposed. The effectiveness and completeness of the mechanical behavior of pavement structure characterized by material parameters were improved. Thus, the utilization rate of waste rubber for pavement construction can be significantly increased and the life cycle cost of asphalt pavement is reduced. (c) 2020 Elsevier Ltd. All rights reserved.
关键词：
Pile-soil interaction;Poroelastic medium;Two-dimensional rod;Radial deformation;Boer's poroelastic model
摘要：
The paper presents an analytical solution for the vertical dynamic interaction analysis of a poroelastic soil layer and an embedded pile with the consideration of pile-soil radial deformations. The soil is treated a three-dimensional porous continuum and described by the Boer's poroelastic model, while the pile is treated as a two-dimensional rod with both radial and vertical deformations of which the equation of motion is derived by the Hamilton's variational principle. Without the introduction of potential functions, first take the volumetric strain of soil skeleton and pore fluid pressure as intermediate variables to deal with the equations of motion for the soil and then use the separation of variables to solve the equations of motion for the soil and the pile. By imposing the boundary and continuity conditions of the pile-soil system, the dynamic impedance in frequency domain and the velocity response in time domain of the pile top are obtained. The present solution is then verified by comparing with the corresponding finite element model computation results and the existing solutions. The effects of the pile-soil parameters on the dynamic characteristic of the pile-soil system are also analyzed. Some significant conclusions are drawn, which can provide useful reference for related engineering practice. (C) 2020 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.
摘要：
The development of the layered cathode material for sodium ion batteries are hindered by synthesis approaches. The sol-gel method is a promising way to prepare the cathodes due to the advantage of mixing the raw product at atomic or molecular level, while the selection criteria for complexing agents are still unclear. Herein, the Na0.9Ni0.45Mn0.55O2 cathode is successfully prepared via sol-gel method, by using sucrose, glucose, citric acid, and ethylene diamine tetra-acetic acid as the chelating agent, respectively. The effects of different chelating agents on the morphologies, structural and electrochemical properties are studied in detail. Electrochemical properties prove that the sample using citric acid shows the best electrochemical performance, delivering a capacity of 96 mAh g(-1) and 48% retention after 300 cycles at 1C, and 59.6 mAh g(-1) of capacity at 10 C rate, which are significantly higher than those of the other samples. XRD and HRTEM are conducted for the cycled electrodes, which demonstrate that the structure of the optimized sample maintains better phase stability and interfacial stability. This work is of considerable significance in understanding the selection criteria for the synthesis of layered cathode chelators for sodium-ion batteries by the sol-gel method. (C) 2020 Elsevier B.V. All rights reserved.
