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Three-dimensional parametric contact analysis of planetary roller screw mechanism and its application in grouping for selective assembly

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Frontiers of Mechanical Engineering 2024年第1期19卷 53-72页

作者： Huilin he Peitang WEI Huaiju LIU Xuesong DU Rui HU Genshen LIU yajun WU State Key Laboratory of Mechanical Transmission for Advanced Equipment Chongqing UniversityChongqing 400044China Taiyuan heavy Machinery Group Co. Ltd.Taiyuan 030024China

The planetary roller screw mechanism(PRSM)is a novel precision transmission mechanism that realizes the conversion between linear and rotary motions.The contact characteristics of helical surfaces directly determine PRSM’s performance in load-carrying capacity and transmission accuracy.Therefore,studying the contact characteristics of PRSM forms the fundamental basis for enhancing its transmission performance.In this study,a three-dimensional parametric analysis method of contact characteristics is proposed based on the PRSM meshing principle and PyVista(a high-level API to the Visualization Toolkit).The proposed method considers the influence of machining errors among various thread teeth.The effects of key machining errors on contact positions and axial clearance,as well as their sensitivities,are analyzed.With excellent solution accuracy,this method exhibits higher calculation efficiency and stronger robustness than the analytical and numerical meshing models.The influence of nominal diameter and pitch errors of the screw,roller,and nut on the axial clearance follows a linear relationship,whereas flank angle errors have negligible effects on the axial clearance.The corresponding influence coefficients for these three machining errors on the axial clearance are 0.623,0.341,and 0.036.The variations in contact positions caused by individual errors are axisymmetric.Flank angle errors and roller diameter errors result in linear displacements of the contact points,whereas pitch errors cause the contact points to move along the arc of the roller diameter.Based on the proposed threedimensional parametric contact characteristics analysis method,the Fuzzy C-Means clustering algorithm considering error sensitivity is utilized to establish a component grouping technique in the selective assembly of critical PRSM components,ensuring the rational and consistent clearances based on the given component’s machining errors.This study provides effective guidance for analyzing contact characteristics and grouping in selective ass

关键词： planetary roller screw mechanism(PRSM) contact position axial clearance machining error grouping for selective assembly

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Cascaded channel decoupling based solution for RIS regulation matrix

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Intelligent and Converged Networks 2024年第1期5卷 19-27页

作者： yajun Zhao Beijing Institute of Technology Beijing 100081China ZTE Corporation Beijing 100029China

This article presents a pioneering solution to address the challenges of reconfigurable intelligent surface(RIS),employing a cascaded channel decoupling strategy.This novel method streamlines the RIS regulation matrix by dividing the process of electromagnetic wave modulation into two separate sub-processes:virtual receiving response and virtual regular transmission,resulting in the decoupling of the RIS cascaded channel.Furthermore,the paper explores the practical implementation of this channel decoupling method in two typical scenarios,including single-user and multi-user access,offering detailed insights into its application.Through numerical simulations,the article demonstrates the effectiveness and reduced complexity of the proposed scheme in enhancing the efficiency of the RIS regulation matrix.

关键词： reconfigurable intelligent surface channel decoupling receiving matrix transmitting matrix

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Inversion of O_(2) 1.27 μm nightglow emissions: A climatological analysis using satellite Limb-Viewed spectra and Harmonic analysis method

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Earth and Planetary Physics 2024年第4期8卷 632-640页

作者： YiYi Sui yajun Zhu QiuYu Chen MaoSheng he JiYao Xu State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Hainan National Field Science Observation and Research Observatory for Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China

This study employs a linear inversion algorithm to retrieve volume emission rates(VERs)of molecular O_(2) nightglow at 1.27μm,utilizing Limb-Viewed spectra obtained from the SCanning Imaging Absorption spectroMeter for Atmospheric for CHartographY(SCIAMACHY)payload on board the Envisat satellite.The retrieved results are compared with VERs data from the SABER payload on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)satellite,exhibiting consistency.This will help to facilitate accurate revelation of spatial distribution and periodic variation in O_(2) nightglow.VERs are extracted monthly within the altitude range of 75-110 km from 2002 to 2012,yielding a climatology of spatial and temporal distributions.The meridional structure exhibits two maxima,at the equator and at 45°N.Between August and October,the VERs exhibit a meridional bimodal structure,with the weaker one above the equator and the stronger one above 45°N.In April,the VERs reach their annual maximum.Additionally,harmonic analysis reveals significant temporal variations on different scales.The emission shows characteristics of annual and semi-annual variation,and a non-linear long-term trend associated with solar cycle activity.

关键词： VERs O_(2)1.27μm nightglow SCIAMACHY

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Recent advances in the biosynthesis of coumarin and its derivatives

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Green Chemical Engineering 2024年第2期5卷 150-154页

作者： Yusong Zou Yuxi Teng Joy Li yajun Yan School of Chemical Materials and Biomedical EngineeringCollege of EngineeringThe University of GeorgiaAthensGA30602USA North Oconee High School BogartGA30622USA

Coumarin and its derivatives,presenting in many organisms(plants,fungi,and bacteria),are critical metabolites composed of fused benzene andα-pyrone rings.With unique biological and chemical properties,coumarin derivatives possess great technological potential in the agrochemicals,pharmaceuticals,food,and cosmetic industries.The increasing demand for coumarin derivatives accelerates the research in biological and chemical synthesis to provide stable and scalable sources of coumarins.However,the complex structures and unknown pathways have limited the progress in the biosynthesis of coumarin derivatives.here,we summarize recent developments and provide a detailed analysis of coumarin derivative biosynthetic pathways in different organisms.

关键词： Coumarin derivatives Biosynthetic pathways Biotransformation Metabolic engineering

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Evaluation of the Oxidation Reactivity and Behavior of Exhaust Soot Particles from Diesel Engines with Different Emission Levels

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China Petroleum Processing & Petrochemical Technology 2024年第2期26卷 72-80页

作者： Wang yajun Lin Lei Xing Jianqiang LüXu Yang he Song Haiqing SINOPEC Research Institute of Petroleum Processing Co. Ltd.Beijing 100083China State Key Laboratory of Engines Tianjin UniversityTianjin 300072China

The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were collected by a thermophoretic system and a quartz filter.The oxidation reactivity,oxidation behaviors,and physicochemical properties of the PM samples were analyzed using thermogravimetric analysis(TGA),high-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectrometry(FTIR),and Raman spectroscopy.The results showed that there was a great difference in the oxidation reactivity of soot particles emitted by the two different diesel engines.A qualitative analysis of the factors influencing oxidation reactivity showed that the nanostructure,degree of graphitization,and relative concentration of aliphatic C—H functional groups were the most important factors,whereas no significant correlation was found between the primary particle size and activation energy of the diesel soot.Based on the oxidation behavior analysis,the diesel soot particles exhibited both internal and surface oxidation modes during the oxidation process.Surface oxidation was dominant during the initial stage,and as oxidation progressed,the mode gradually changed to internal oxidation.Internal oxidation mode of soot particles from the 1K engine was significantly higher than that of CY4102.

关键词： diesel engine soot particles oxidation reactivity oxidation behavior

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Introducing urea into tirapazamine derivatives to enhance anticancer therapy

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National Science Review 2024年第4期11卷 245-253页

作者： yajun Xu Jianlin Lv Chaoying Kong Ya Liu Kun Wang Zhaohui Tang Xuesi Chen Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of Sciences School of Applied Chemistry and Engineering University of Science and Technology of China

Tirapazamine（TPZ） has been approved for multiple clinical trials relying on its excellent anticancer potential.However,as a typical hypoxia-activated prodrug（HAP）,TPZ did not exhibit survival advantages in Phase Ⅲ clinical trials when used in combination therapy due to the insufficient hypoxia levels in patients' tumors.In this study,to improve the therapeutic effects of TPZ,we first introduced urea to synthesize a series of urea-containing derivatives of TPZ.All urea-containing TPZ derivatives showed increased hypoxic cytotoxicity（9.51-30.85-fold） compared with TPZ,while maintaining hypoxic selectivity.TPZP,one of these derivatives,showed 20-fold higher cytotoxicity than TPZ while maintaining a similar hypoxic cytotoxicity ratio.To highly efficiently deliver TPZP to the tumors and reduce its side effects on healthy tissues,we further prepared TPZP into a nanodrug with fibrin-targeting ability:FT11-TPZP-NPs.CA4-NPs,a vascular disrupting agent,was used to increase the fibrin level within tumors and exacerbate tumor hypoxia.By being combined with CA4-NPs,FT11-TPZP-NPs can accumulate in the hypoxia-aggravated tumors and activate sufficiently to kill tumor cells.After a single-dose treatment,FT11-TPZP-NPs+CA4-NPs showed a high inhibition rate of 98.1% against CT26 tumor models with an initial volume of ～480 mm3and four out of six tumors were completely eliminated;it thereby exerted a significant antitumor effect.This study provides a new strategy for improving the therapeutic effect of TPZ and other HAPs in anticancer therapy.

关键词： tirapazamine vascular disrupting agent hypoxia-activated prodrug combretastatin A4 urea

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Photomediated core modification of diaryl dihydrophenzines through three-component alkylarylation of alkenes toward organocatalyzed ATRP

Green Synthesis and Catalysis

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Green Synthesis and Catalysis 2024年第1期5卷 35-41页

作者： yajun Zhang Hao Wang Dandan Jiang Naixian Sun Wei he Lili Zhao Ning Qin Ning Zhu Zheng Fang Kai Guo College of Biotechnology and Pharmaceutical Engineering State Key Laboratory of Materials-Oriented Chemical EngineeringNanjing Tech UniversityNanjing211800China Institute of Advanced Synthesis School of Chemistry and Molecular EngineeringNanjing Tech UniversityNanjing211800China Department of Mechanical Engineering The University of SheffieldSheffieldS13JDUnited Kingdom

The design and synthesis of a novel organic photocatalyst(OPC)have attracted broad interest from both the organic chemistry and polymer community.herein,we presented a visible-light-induced alkylarylation of alkenes strategy for core modification of 5,10-diaryl-5,10-dihydrophenazines(DADHPs)under metal-and additive-free conditions,with the aim to develop powerful photocatalyst for organocatalyzed atom transfer radical polymerization(O-ATRP).Good tolerance for a wide variety of functional groups and affording the corresponding tetrasubstituted products in moderate to good yields were achieved in the batch and flow reactor.The experimental and computational mechanistic study confirmed that DADHPs’radical cations andπ-πstacking interactions played important roles in the alkylarylation of alkenes.A series of the tetrasubstituted DADHPs were directly synthesized from the corresponding noncore-modified phenazines,which were demonstrated to be effective organic photoredox catalysts for O-ATRP.Light responsive nature,controlled polymerization manner,and welldefined poly(methyl methacrylate)were achieved via tetrasubstituted DADHPs mediated O-ATRP.

关键词： Photoinduced Core modification Diaryl dihydrophenzine O-ATRP

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Regulating surface electron structure of PtNi nanoalloy via boron doping for high‐current‐density Li‐O2 batteries with low overpotential and long‐life cyclability

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SmartMat 2024年第1期5卷 110-120页

作者： yajun Ding Yuanchao Huang Yuejiao Li Tao Zhang Zhong‐Shuai Wu State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalianChina State Key Laboratory of Silicon Materials and School of Materials Science and Engineering Zhejiang UniversityHangzhouChina Institute of Advanced Semiconductors Hangzhou Innovation CenterZhejiang UniversityHangzhouChina University of Chinese Academy of Sciences BeijingChina State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghaiChina Dalian National Laboratory for Clean Energy Chinese Academy of SciencesDalianChina

The realization of high‐efficiency,reversible,stable,and safe Li‐O2 batteries is severely hindered by the large overpotential and side reactions,especially at high rate conditions.Therefore,rational design of cathode catalysts with high activity and stability is crucial to overcome the terrible issues at high current density.herein,we report a surface engineering strategy to adjust the surface electron structure of boron(B)‐doped PtNi nanoalloy on carbon nanotubes(PtNiB@CNTs)as an efficient bifunctional cathodic catalyst for high‐rate and long‐life Li‐O2 batteries.Notably,the Li‐O2 batteries assembled with as‐prepared PtNiB@CNT catalyst exhibit ultrahigh discharge capacity of 20510 mA·h/g and extremely low overpotential of 0.48 V at a high current density of 1000 mA/g,both of which outperform the most reported Pt‐based catalysts recently.Meanwhile,our Li‐O2 batteries offer excellent rate capability and ultra‐long cycling life of up to 210 cycles at 1000 mA/g under a fixed capacity of 1000 mA·h/g,which is two times longer than those of Pt@CNTs and PtNi@CNTs.Furthermore,it is revealed that surface engineering of PtNi nanoalloy via B doping can efficiently tailor the electron structure of nanoalloy and optimize the adsorption of oxygen species,consequently delivering excellent Li‐O2 battery performance.Therefore,this strategy of regulating the nanoalloy by doping nonmetallic elements will pave an avenue for the design of high‐performance catalysts for metal‐oxygen batteries.

关键词： B doping bifunctional catalyst Li‐O2 battery low charge overpotential PtNi nanoalloy

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Paradigm for Determining the Optimal Ultradeep and Superthick Saline Aquifer for High-TDS Mine Water Geological Storage

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 771-785页

作者： LI Xin CheN Ge XU Zhimin LIU Qi CheN Tianci SUN yajun School of Resources and Geosciences China University of Mining and TechnologyXuzhouJiangsu 221116China National Professional Central Laboratory of Basic Research on Mine Water Disaster Prevention and Control Technology XuzhouJiangsu 221116China

Saline aquifers are the most popular waste and CO_(2)injection and storage reservoirs worldwide.This project proposes that several optimal injection positions should be investigated as hydraulic pressure-focused positions,in order to relieve the high demands of pump performance.The comprehensive indices(F_(i))representing the injectivity of different burial depths were obtained by using information entropy,based on the mercury injection experimental data of 13 rock samples.The results demonstrated that the burial depths of No.4,No.1 and No.2 in the Liujiagou Formation were the most suitable positions for hydraulic focused injection,which means the upper 30 m thickness could be regarded as the hydraulic focused range in the saline aquifer with an average thickness of 400 m.In addition,some laboratory experiments and in situ tests were carried out for the purpose of certifying and analyzing results,including SEM,XRD,brittleness index and logging.The results suggested that the rock samples at the No.4,No.1 and No.2 burial depth ranges have loose microstructure,weak cementation,as well as dual pores and fractures.The lithology is mainly quartz and feldspar,but the clay mineral content is high(10%-25%),which is positive for dissolution.The lithology is suitable for hydraulic fracturing to form extended cracks and micro-fissures during high-TDS(total dissolved solids)mine water injection,because of the high brittleness index.Finally,a theoretical and technical framework for high-TDS mine water injection was established,based on operating pilot engineering.Some theoretical defects and drawbacks learned from the field practices were summarized and solutions proposed.The research in this study could provide guidance and a paradigm for the inexpensive treatment of high-TDS mine water by injection and storage.

关键词： ultradeep Liujiagou Formation high-TDS mine water optimal hydraulic injection positions information entropy reservoir spatial characteristics

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Cu-catalyzed regioselective diborylation of 1,3-enynes for the efficient synthesis of 1,4-diborylated allenes

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Chinese Chemical Letters 2024年第5期35卷 141-144页

作者： Wujun Jian Mong-Feng Chiou yajun Li Hongli Bao Song Yang National Key Laboratory of Green Pesticide Key Laboratory of Green Pesticide and Agricultural BioengineeringMinistry of EducationCenter for R&D of Fine Chemicals of Guizhou UniversityGuiyang 550025China Strait Institute of Flexible Electronics(SIFE Future Technologies)Fujian Normal UniversityFuzhou 350117China Key Laboratory of Coal to Ethylene Glycol and Its Related Technology State Key Laboratory of Structural ChemistryFujian Institute of Research on the Structure of MatterUniversity of Chinese Academy of SciencesFuzhou 350002China

Borylation of 1,3-enynes with bis(boronate)compounds often ends up with the formation of hydroborylated products,leaving the diborylation of 1,3-enynes for the formation of 1,4-diborylated allenes to be challenging.herein,a copper-catalyzed chemo-,regio-,and stereo-selective diborylation of 1,3-enynes for the efficient construction of 1,4-diborylated allenes under base-free conditions was reported.A wide range of 1,3-enynes bearing various functional groups can participant in the reaction and afforded the corresponding 1,4-diborylated allenes in good to excellent yields,which was enabled by the protocol of Bpin to BF3K conversion.the borylcopper species was supposed to selectively attack the C-C triple bond of the 1,3-enynes.

关键词： Copper catalysis Regioselective 1,3-Enynes Borylation Allenes

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