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Microwave-assisted synthesis of diaryl or aryl-alkyl sulfones without catalyst

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Chinese Chemical Letters 2009年第1期20卷 17-20页

作者： Jiong Zou feng li feng Gang Tao Department of Chemistry Fudan University Shanghai 200433 China

The microwave-assisted coupling reaction of electrondeficient aryl halides with sulfinic acid salts through SNAr-based addition reactions within 5-30 min. No catalysts were required under our conditions.

关键词： Microwave Sulfone SNAr-based addition reaction

Solar sail time-optimal interplanetary transfer trajectory design

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Research in Astronomy and Astrophysics 2011年第8期11卷 981-996页

作者： Sheng-Ping Gong Yun-feng Gao Jun-feng li School of Aerospace Tsinghua University Beijing 100084 China

The fuel consumption associated with some interplanetary transfer trajectories using chemical propulsion is not affordable. A solar sail is a method of propulsion that does not consume fuel. Transfer time is one of the most pressing problems of solar sail transfer trajectory design. This paper investigates the time-optimal interplanetary transfer trajectories to a circular orbit of given inclination and radius. The optimal control law is derived from the principle of maximization. An indirect method is used to solve the optimal control problem by selecting values for the initial adjoint vari- ables, which are normalized within a unit sphere. The conditions for the existence of the time-optimal transfer are dependent on the lightness number of the sail and the inclination and radius of the target orbit. A numerical method is used to obtain the boundary values for the time-optimal transfer trajectories. For the cases where no time-optimal transfer trajectories exist, first-order necessary conditions of the optimal control are proposed to obtain feasible solutions. The results show that the transfer time decreases as the minimum distance from the Sun decreases during the transfer duration. For a solar sail with a small lightness number, the transfer time may be evaluated analytically for a three-phase transfer trajectory. The analytical results are compared with previous results and the associated numerical results. The transfer time of the numerical result here is smaller than the transfer time from previous results and is larger than the analytical result.

关键词： techniques: miscellaneous -- solar sail -- solar polar orbit

分散固相萃取-超高效液相色谱-串联质谱法测定饲料中的多肽类抗生素

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饲料研究 2024年第5期47卷 109-116页

作者：黄燕李燕妹陈言凯梁敏冯丽凤陈何燊林浩学蔡小明福建省产品质量检验研究院国家加工食品质量检验检测中心(福州) 福建福州350000

试验基于分散固相萃取净化结合超高效液相色谱-串联质谱法,建立一种同时测定饲料中16种多肽类抗生素(PPTs)的定量分析方法。样品经1%三氯乙酸(aq)-甲醇溶液提取,十八烷基硅胶(C18)分散固相萃取净化后上机测定。在电喷雾正电离模式下,使... 详细信息

试验基于分散固相萃取净化结合超高效液相色谱-串联质谱法,建立一种同时测定饲料中16种多肽类抗生素(PPTs)的定量分析方法。样品经1%三氯乙酸(aq)-甲醇溶液提取,十八烷基硅胶(C18)分散固相萃取净化后上机测定。在电喷雾正电离模式下,使用多反应监测(MRM)模式,基质匹配校正曲线定量。结果显示,PPTs在相应的浓度范围内线性关系良好,相关系数(R2)大于0.99,检出限为0.4~12.1μg/kg,定量限为1.4~40.4μg/kg。PPTs在饲料中的平均回收率(n=6)为80.0%~114.4%,相对标准偏差(RSD)为2.33%~9.51%。研究表明,该方法操作简单、准确可靠、灵敏度高、分析时间短且重现性高,可广泛应用于饲料中16种PPTs的快速筛查和常规监测。

关键词：超高效液相色谱-串联质谱多肽类抗生素饲料分散固相萃取

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轴上物点经双凸对称球面透镜成像偏差分析

大学物理 2024年第7期43卷 81-84页

作者：于晨曦冯立峰孙文军哈尔滨师范大学物理与电子工程学院黑龙江哈尔滨150025

为确定轴上物点经双凸对称球面透镜所成的像与理想像的差异,便于检验成像器件能否达到实际成像应用要求,本文利用解析几何方法推导了轴上物点经双凸对称球面透镜的成像区域边界方程,计算分析了入射光线倾角及透镜参数对成像区域的影响.... 详细信息

为确定轴上物点经双凸对称球面透镜所成的像与理想像的差异,便于检验成像器件能否达到实际成像应用要求,本文利用解析几何方法推导了轴上物点经双凸对称球面透镜的成像区域边界方程,计算分析了入射光线倾角及透镜参数对成像区域的影响.结果表明当轴上物点位置与透镜曲率半径确定时,如物距取30.0 cm、曲率半径为15.0 cm、透镜的半厚度≤0.300 cm时,表示成像区域边界轴上像点偏离理想像点程度的轴上偏差小于等于2.02%;当轴上物点位置与透镜参数确定,如物距取30.0 cm、透镜半通光孔径为3.00 cm、入射光线倾角≤4.85°时,表示成像区域边界像点离轴程度的离轴偏差小于等于10.0%.此方法同样可以分析其他类型像差,理论推导与计算结果为相关后续研究提供了理论支持与技术借鉴.

关键词：几何光学双凸球面透镜理想成像成像区域

A novel method for AFRPs burrs removal:Principle of mechanochemo-induced fiber fracture

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Chinese Journal of Aeronautics 2024年第7期37卷 522-538页

作者： Jie XU Bo li Pingfa feng Qiang WANG feng feng Division of Advanced Manufacturing Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Changhe Aircraft Industry(Group)Co.Ltd Jingdezhen 333000China

Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing *** studies have generally attempted to suppress burrs by referring to delamination suppression *** contrast to stratification,burrs are remediable machining *** such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat ***,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical *** addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are ***,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical *** method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.

关键词： Mechanochemical method Burrs Orthogonal cutting Aramid fiber-reinforced composites Milling

Plasma-etching on monolithic MOFs-based MIM filter boosted chemical sensing

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Nano Research 2024年第4期17卷 2800-2807页

作者： Jianxi liu li feng Zhihuan li Yang Wu feng Zhou Yadong Xu Research&Development Institute Northwestern Polytechnical University in ShenzhenShenzhen 518057China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Yantai Zhongke Research Institute of Advanced Materials and Green Chemical Engineering Shandong Laboratory of Advanced Materials and Green Manufacturing at YantaiYantai 264006China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Metal-insulator-metal(MIM)cavity as a lithography-free structure to control light transmission and reflection has great potential in the field of optical ***,the dense top metal layer of the MIM prohibits any external medium from entering the dielectric insulation layer,which limits the application of the cavity in the sensing ***,we demonstrate a series of monolithic metal-organic frameworks(MOFs)based MIM cavities,which are treated by plasma etching to provide channels for chemical diffusion and to advance *** modulate the bandwidth of the MIM filters by controlling the MOF thickness as insulator *** plasma-etching is applied to build channels on the top metal layer without altering their saturation and brightness for chemical sensing *** etching time regulates the number and size of channels on the top metal *** behavior is demonstrated on the plasma-etched MOFs-based MIM cavity when external chemicals diffuse in the *** addition,we generate patterned structure of the MOFs-based MIM cavity via plasma-mask method,which can transfer to different substrates and produce a controllable structure color change for chemical *** MIM cavity may promote the advancement and applications of structural color in security imaging,color display,information anticounterfeiting,and color printing.

关键词： metal-organic frameworks(MOFs) spin-coating metal-insulator-metal filter patterns sensing

Small-molecule 7,8-dihydroxyflavone counteracts compensated and decompensated cardiac hypertrophy via AMPK activation

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Journal of Geriatric Cardiology 2022年第11期19卷 853-866页

作者： Peng-Zhou HANG Pei-feng li Jie liU feng-feng li Ting-Ting CHEN Yang PAN Man-Ru ZHANG Hua-Qing YU Hong-Yu JI Zhi-Min DU Jing ZHAO Institute of Clinical Pharmacology the Second Affiliated Hospital of Harbin Medical University(University Key Laboratory of Drug ResearchHeilongjiang Province)HarbinChina Department of Pharmacy Clinical Medical CollegeYangzhou UniversityNorthern Jiangsu People's HospitalYangzhouChina Department of Pharmacology Harbin Medical UniversityHarbinChina State Key Laboratory of Quality Research in Chinese Medicines Macao University of Science and TechnologyMacaoChina Department of Cardiology the First Affiliated Hospital of Harbin Medical UniversityHarbinChina

BACKGROUND Pathological cardiac hypertrophy is a compensated response to various stimuli and is considered a key risk factor for heart failure.7,8-Dihydroxyflavone(7,8-DHF)is a flavonoid derivative that acts as a small-molecule brain-derived neurotrophic factor *** present study aimed to explore the potential role of 7,8-DHF in cardiac *** Kunming mice and H9c2 cells were exposed to transverse aortic constriction or isoproterenol(ISO)with or without 7,8-DHF,respectively.F-actin staining was performed to calculate the cell *** levels of hypertrophic markers,including ANP,BNP,andβ-MHC,were ***,hematoxylin-eosin staining,and transmission electron microscopy were used to examine the cardiac function,histology,and ultrastructure of *** levels of mitochondria-related factors,such as adenosine monophosphate-activated protein kinase(AMPK),and peroxisome proliferator-activated receptorγcoactivator-1α(PGC-1α),were *** 7,8-DHF inhibited compensated and decompensated cardiac hypertrophy,diminished the cross-sectional area,and alleviated the mitochondrial disorders of ***,7,8-DHF reduced the cell size and repressed the mRNA levels of the hypertrophic markers of ISO-treated *** addition,7,8-DHF activated AMPK and PGC-1αsignals without affecting the protein levels of mitochondrial dynamics-related *** effects of 7,8-DHF were eliminanted by Compound C,an AMPK *** These findings suggest that 7,8-DHF inhibited cardiac hypertrophy and mitochondrial dysfunction by activating AMPK signaling,providing a potential agent for the treatment of pathological cardiac hypertrophy.

关键词： cardiac hypertrophy inhibited

A Lower Bound for the Heegaard Genera of Annulus Sum

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Journal of Mathematical Research and Exposition 2011年第4期31卷 578-586页

作者： feng ling li feng Chun LEI School of Mathematical Sciences Dalian University of Technology Liaoning 116024 P. R. China

Let Mi, i = 1,2, be a compact orientable 3-manifold, and Ai an incompressible annulus on a component Fi of OMi. Suppose A1 is separating on F1 and A2 is non-separating on F2. Let M be the annulus sum of M1 and M2 along A1 and A2. In the present paper, we give a lower bound for the genus of the annulus sum M in the condition of the Heegaard distances of the submanifolds M1 and M2

关键词： genus distance annulus.

A UNIFORM CONVERGENT PETROV-GALERKIN METHOD FOR A CLASS OF TURNING POINT PROBLEMS

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Journal of Computational Mathematics 2024年第5期42卷 1356-1379页

作者： li feng Zhongyi Huang Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China

In this paper,we propose a numerical method for turning point problems in one dimension based on Petrov-Galerkin finite element method(PGFEM).We first give a priori estimate for the turning point problem with a single boundary turning *** we use PGFEM to solve it,where test functions are the solutions to piecewise approximate dual *** prove that our method has a first-order convergence rate in both L∞h norm and a discrete energy norm when we select the exact solutions to dual problems as test *** results show that our scheme is efficient for turning point problems with different types of singularities,and the convergency coincides with our theoretical results.

关键词： Turning point problem Petrov-Galerkin finite element method Uniform convergency