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Science China Chemistry 2021年第9期64卷 1522-1529页

作者： Zhanghong Guo Xiaowei Chen Hao Fang xiaowei Zhao Zhiyong Jiang International Scientific and Technological Cooperation Base of Chiral Chemistry Henan UniversityKaifeng475004China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang453007China

The first enantioselective Beckwith-Enholm cyclization reaction is reported herein.Under cooperative photoredox and chiral hydrogen-bonding catalysis mediated by visible light,cyclization of carbonyls with azaarene-based olefins as a new reaction system offers a general and divergent synthetic pathway to furnish a variety of highly valuable enantioenriched azaarenefunctionalized carbocyclic and heterocyclic alcohols,which bear adjacent 1,2-or nonadjacent 1,3-stereocentres on distinct cyclic frameworks,in high yields and enantio-and diastereoselectivities.The good compatibility of various azaarenes and carbonyls as well as the diversity of cyclic structures of the products underscores the generality of the catalysis platform.In addition to the ability to precisely introduce deuterium into molecules in an enantioselective manner,the considerable synthetic value of this method includes the excellent antioxidant stress potential of the products.In particular,molecule 29 was determined to be a promising lead compound for antioxidant stress drug design.

关键词： photoredox catalysis asymmetric catalysis Beckwith-Enholm cyclizations azaarenes antioxidant stress

Fourth-Order Structure-Preserving Method for the Conservative Allen-Cahn Equation

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Advances in Applied Mathematics and Mechanics 2023年第1期15卷 159-181页

作者： Xiaowei Chen Xu Qian Songhe Song Department of Mathematics National University of Defense TechnologyChangshaHunan 410073China

We propose a class of up to fourth-order maximum-principle-preserving and mass-conserving schemes for the conservative Allen-Cahn equation equipped with a non-local Lagrange multiplier.Based on the second-order finite-difference semidiscretization in the spatial direction,the integrating factor Runge-Kutta schemes are applied in the temporal direction.Theoretical analysis indicates that the proposed schemes conserve mass and preserve the maximum principle under reasonable time step-size restriction,which is independent of the space step size.Finally,the theoretical analysis is verified by several numerical examples.

关键词： Maximum-principle-preserving mass-conserving scheme the conservative AllenCahn equation

Study on damage mechanism and damage distribution of the rear plate under impact of debris cloud

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Defence Technology（防务技术） 2024年第5期35卷 151-167页

作者： chenyang Wu Xiaowei Chen Qiguang He State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyHaidian DistrictBeijing 100081China School of Mechatronical Engineering Beijing Institute of TechnologyHaidian DistrictBeijing 100081China Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621900SichuanChina

The debris cloud generated by the hypervelocity impact(HVI)of orbiting space debris directly threatens the spacecraft.A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective structures.In this study,the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method,and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud structure.The damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear plate.The main impact stage lasts a short time and is the basis of the rear plate damage.In the stage of structure response,the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear plate.We further analyze the damage mechanism and damage distribution characteristics of the rear plate in detail.Moreover,the connection between velocity space and position space of the debris cloud is established,which promotes the general analysis of the damage law of debris cloud.Based on the relationship,the features of typical damage areas are identified by the localized fine analysis.Both the cumulative effect and structural response cause the perforation of rear plate;in the non-perforated area,cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

关键词： Damage of rear plate Debris cloud Secondary impact Hypervelocity yaw impact FE-SPH adaptive method

Renal Pathology Images Segmentation Based on Improved Cuckoo Search with Diffusion Mechanism and Adaptive Beta-Hill Climbing

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Journal of Bionic Engineering 2023年第5期20卷 2240-2275页

作者： Jiaochen chen Zhennao Cai Huiling chen Xiaowei Chen José Escorcia-Gutierrez Romany F.Mansour Mahmoud Ragab College of Computer Science and Artificial Intelligence Wenzhou UniversityWenzhou325035China Department of Rheumatology and Immunology The First Affiliated Hospital of Wenzhou Medical UniversityWenzhou325000China Department of Computational Science and Electronics Universidad de la CostaCUC080002BarranquillaColombia Department of Mathematics Faculty of ScienceNew Valley University72511El-KhargaEgypt Information Technology Department Faculty of Computing and Information TechnologyKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Mathematics Faculty of ScienceAl-Azhar UniversityNaser CityCairo11884Egypt

Lupus Nephritis(LN)is a significant risk factor for morbidity and mortality in systemic lupus erythematosus,and nephropathology is still the gold standard for diagnosing LN.To assist pathologists in evaluating histopathological images of LN,a 2D Rényi entropy multi-threshold image segmentation method is proposed in this research to apply to LN images.This method is based on an improved Cuckoo Search(CS)algorithm that introduces a Diffusion Mechanism(DM)and an Adaptiveβ-Hill Climbing(AβHC)strategy called the DMCS algorithm.The DMCS algorithm is tested on 30 benchmark functions of the IEEE CEC2017 dataset.In addition,the DMCS-based multi-threshold image segmentation method is also used to segment renal pathological images.Experimental results show that adding these two strategies improves the DMCS algorithm's ability to find the optimal solution.According to the three image quality evaluation metrics:PSNR,FSIM,and SSIM,the proposed image segmentation method performs well in image segmentation experiments.Our research shows that the DMCS algorithm is a helpful image segmentation method for renal pathological images.

关键词： Multi-threshold image segmentation 2D Rényi entropy Renal pathology Cuckoo search algorithm Swarm intelligence algorithms Bionic algorithm

Phytosterols in edible oil:Distribution,analysis and variation during processing

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Grain & Oil Science and Technology 2021年第1期4卷 33-44页

作者： Ge Bai Chuanguo Ma Xiaowei Chen College of Food Science and Engineering Henan University of TechnologyZhengzhou 450001China

Phytosterols,which are naturally occurring in plants,have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular diseases.Edible oils are the main source of daily intake of phytosterols,whereas the properties of phytosterols may vary a lot depending on their sources.During the processing of edible oil including refining and frying,phytosterol's content fluctuates,which influences the properties of the final product.Phytosterols and their derivatives undergo physical migration between different phases and chemical conversion during the processing,which reduces the quality and the commercial value of edible oils.Therein,the loss of phytosterols is the major concern in the process of neutralization and deodorization.In addition,oxidation and thermal degradation of phytosterols occur simultaneously during frying,which also reduces the content of phytosterols.Nevertheless,the oil matrix has a promoting or an inhibitory effect on the thermal oxidation of phytosterols.Therefore,various efforts have been devoted to analyzing and improving the remaining contents of phytosterols in edible oil.Regardless of the processing method,temperature plays an important role in the loss of phytosterols.At present,themain analysismethods of phytosterols include gas chromatography and liquid chromatography,inwhich the pretreatment of different types of phytosterols is also a crucial step.This review focused on the following topics comprehensively:(i)the distribution of phytosterols in the oil-containing plants and edible oils during the refining processing;(ii)the pretreatment and analysis methods of various phytosterols(free phytosterols,phytosteryl fatty acid esters,phytosteryl glycosides and acylated phytosteryl glycosides);(iii)the variation of phytosterols in process of esterification and oxidation,storage and so on.The study also proposed that the investigation in the loss and safety of phytosterols during processing of the vegetable oils should be proceeded further in c

关键词： Phytosterols Edible oil Distribution Gas chromatography High performance liquid chromatography Oil refining

Numerical Modeling of Natural Fracture Distributions in Shale

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Acta Geologica Sinica(English Edition) 2023年第3期97卷 828-840页

作者： LI Yaping chen xiaowei SHAO Yongbo School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Civil Engineering and Geomatics Southwest Petroleum UniversityChengdu 610500China

The production efficiency of shale gas is affected by the interaction between hydraulic and natural fractures.This study presents a simulation of natural fractures in shale reservoirs,based on a discrete fracture network(DFN)method for hydraulic fracturing engineering.Fracture properties of the model are calculated from core fracture data,according to statistical mathematical analysis.The calculation results make full use of the quantitative information of core fracture orientation,density,opening and length,which constitute the direct and extensive data of mining engineering.The reliability and applicability of the model are analyzed with regard to model size and density,a calculation method for dominant size and density being proposed.Then,finite element analysis is applied to a hydraulic fracturing numerical simulation of a shale fractured reservoir in southeastern Chongqing.The hydraulic pressure distribution,fracture propagation,acoustic emission information and in situ stress changes during fracturing are analyzed.The results show the application of fracture statistics in fracture modeling and the influence of fracture distribution on hydraulic fracturing engineering.The present analysis may provide a reference for shale gas exploitation.

关键词： shale core natural fracture discrete fracture network(DFN) hydraulic fracturing

Hydrophilic phytosterol derivatives: A short review on structural modifications, cholesterol-lowering activity and safety

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Grain & Oil Science and Technology 2022年第3期5卷 146-155页

作者： Yuyuan Hu Chuanguo Ma Xiaowei Chen Ge Bai Shujing Guo College of Food Science and Engineering Henan University of TechnologyZhengzhou 450001China

Phytosterols have received extensive attention owing to their excellent cholesterol-lowering activity and the role in cardiovascular diseases prevention. However, poor solubility in both oil and water limited the application of free phytosterols in the food industry. Chemical or enzymatic modifications were effective to improve the physicochemical properties as well as the bioavailability and cholesterollowering activity of phytosterols. Higher oil solubility and lower melting point of phytosterols have been achieved by esterification and transesterification with fatty acids and triacylglycerols so as to enhance the bioavailability, reduce formation of precipitates, and improve the sensory quality of products.While the researches on the improvement on its water solubility is a hot topic. Hydrophilic phytosterol derivatives have promising applications in the food industry because most of foods belong to aqueous matrix. Hydrophilic modification is useful and meaningful for phytosterols in both industrial and commercial applications. This review mainly highlights the hydrophilic phytosterol derivatives in the following aspects:(i) hydrophilic modifications of phytosterols by coupling with various polar components;(ii) cholesterol-lowering activity and possible molecular mechanisms of hydrophilic phytosterol derivatives on reducing serum cholesterol level;and(iii) safety evaluation of hydrophilic phytosterol derivatives in cell-culture studies, animal models and clinical trials.

关键词： Hydrophilic modification Hydrophilic phytosterol derivatives Water solubility Cholesterol-lowering Mechanism

Multi-scale finite element simulation on large deformation behavior of wood under axial and transverse compression conditions

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Acta Mechanica Sinica 2021年第7期37卷 1136-1151,I0002页

作者： Weizhou Zhong Zexiong Zhang Xiaowei Chen Qiang Wei Gang chen Xicheng Huang Institute of Systems Engineering China Academy of Engineering PhysicsMianyang Sichuan621999China Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province Mianyang 621999China College of Engineering Science University of Science and Technology of ChinaHefei 230026China Advanced Research Institute for Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China The State Key Lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

Multi-scale finite element method is adopted to simulate wood compression behavior under axial and transverse loading. Representative volume elements (RVE) of wood microfibril and cell are proposed to analyze orthotropic mechanical behavior. Lignin, hemicellulose and crystalline-amorphous cellulose core of spruce are concerned in spruce nanoscale model. The equivalent elastic modulus and yield strength of the microfibril are gained by the RVE simulation. The anisotropism of the crystalline-amorphous cellulose core brings the microfibril buckling deformation during compression loading. The failure mechanism of the cell-wall under axial compression is related to the distribution of amorphous cellulose and crystalline cellulose. According to the spruce cell observation by scanning electron microscope, numerical model of spruce cell is established using simplified circular hole and regular hexagon arrangement respectively. Axial and transverse compression loadings are taken into account in the numerical simulations. It indicates that the compression stress-strain curves of the numerical simulation are consistent with the experimental results. The wood microstructure arrangement has an important effect on the stress plateau during compression process. Cell-wall buckling in axial compression induces the stress value drops rapidly. The wide stress plateau duration means wood is with large energy dissipation under a low stress level. The numerical results show that loading velocity affects greatly wood microstructure failure modes in axial loading. For low velocity axial compression, shear sliding is the main failure mode. For high velocity axial compression, wood occur fold and collapse. In transverse compression, wood deformation is gradual and uniform, which brings stable stress plateau.

关键词： Multi-scale model Representative volume element Spruce Energy dissipation Wood cell

Fuzzy cost-profit tradeoff model for locating a vehicle inspection station considering regional constraints

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第12期15卷 1138-1146页

作者： Guangdong TIAN Hua KE Xiaowei Chen Transportation College Northeast Forestry University School of Economics and Management Tongji University Department of Risk Management and Insurance Nankai University

Facility location allocation(FLA) is one of the important issues in the logistics and transportation fields. In practice, since customer demands, allocations, and even locations of customers and facilities are usually changing, the FLA problem features uncertainty. To account for this uncertainty, some researchers have addressed the fuzzy profit and cost issues of FLA. However, a decision-maker needs to reach a specific profit, minimizing the cost to target customers. To handle this issue it is essential to propose an effective fuzzy cost-profit tradeoff approach of FLA. Moreover, some regional constraints can greatly influence FLA. By taking a vehicle inspection station as a typical automotive service enterprise example, and combined with the credibility measure of fuzzy set theory, this work presents new fuzzy cost-profit tradeoff FLA models with regional constraints. A hybrid algorithm integrating fuzzy simulation and genetic algorithms(GA) is proposed to solve the proposed models. Some numerical examples are given to illustrate the proposed models and the effectiveness of the proposed algorithm.

关键词： Cost-profit tradeoff Credibility theory Fuzzy simulation Fuzzy programming Genetic algorithm

Preface to the special collection of Induced Earthquakes

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Earth and Planetary Physics 2021年第6期5卷 483-484页

作者： HongFeng Yang Xiaowei Chen Rebecca Harrington YaJing Liu Earth System Science Programme Faculty of ScienceThe Chinese University of Hong KongShatinNTHong KongChina School of Geosciences The University of OklahomaNormanOklahomaUSA Institute for Geology Mineralogy&GeophysicsRuhr University BochumBochumGermany Department of Earth and Planetary Sciences McGill UniversityMontréalQuébecCanada

It has been long recognized that a variety of anthropogenic activities may cause earthquakes(Ellsworth et al.,2013;Yang HF et al.,2017).In the recent decades,induced earthquakes have been found in many settings and be... 详细信息

关键词： setting Earthquake earthquakes