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An unsplit complex frequency-shifted perfectly matched layer for second-order acoustic wave equations

Science China Earth Sciences 2021年第6期64卷 992-1004页

作者： Xiuzheng fang Fenglin niu State Key Laboratory of Petroleum Resources and Prospecting and Unconventional Petroleum Research InstituteChina University of PetroleumBeijing102249China Department of Earth Environmental and Planetary SciencesRice UniversityHoustonTexas77005USA

The perfectly matched layer(PML)boundary condition has been proven to be effective for attenuating reflections from model boundaries during wavefield simulation.As such,it has been widely used in time-domain finite-difference wavefield simulations.The conventional PML has poor performance for near grazing incident waves and low-frequency reflections.To overcome these limitations,a more complex frequency-shifted stretch(CSF)function is introduced,which is known as the CFSPML boundary condition and can be implemented in the time domain by a recursive convolution technique(CPML).When implementing the PML technique to second-order wave equations,all the existing methods involve adding auxiliary terms and rewriting the wave equations into new second-order partial differential equations that can be simulated by the finite-difference scheme,which may affect the efficiency of numerical simulation.In this paper,we propose a relatively simple and efficient approach to implement CPML for the second-order equation system,which solves the original wave equations numerically in the stretched coordinate.The spatial derivatives in the stretched coordinate are computed by adding a correction term to the regular derivatives.Once the first-order spatial derivatives are computed,we computed the second-order spatial derivatives in a similar way;therefore,we refer to the method as two-step CPML(TS-CPML).We apply the method to the second-order acoustic wave equation and a coupled second-order pseudo-acoustic TTI wave equation.Our simulations indicate that amplitudes of reflected waves are only about half of those computed with the traditional CPML method,suggesting that the proposed approach has computational advantages and therefore can be widely used for forwarding modeling and seismic imaging.

关键词： PML CPML Absorbing boundary condition Finite-difference Second-order wave equation Numerical modeling

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On the Mixed Pólya–Szegö Principle

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Acta Mathematica Sinica,English Series 2021年第5期37卷 753-767页

作者： niu Fa fang Jia Zu ZHOU Chern Institute of Mathematics Nankai UniversityTianjin 300071P.R.China School of Mathematics and Statistics Southwest UniversityChongqing 400715P.R.China College of Science Wuhan University of Science and TechnologyWuhan 430081P.R.China

In this paper,the mixed Pólya-Szegöprinciple is established.By the mixed Pólya-Szegöprinciple,the mixed Morrey-Sobolev inequality and some new analytic inequalities are obtained.

关键词： Pólya–Szegöprinciple mixed Pólya–Szegöprinciple Sobolev inequality spherically symmetric rearrangement

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Precise Evolutionary Asteroseismology of High-AmplitudeδScuti Star AE Ursae Majoris

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Research in Astronomy and Astrophysics 2022年第10期22卷 61-76页

作者： Hui-fang Xue Jia-Shu niu Jian-Ning Fu Department of Physics Taiyuan Normal UniversityJinzhong 030619China Institute of Computational and Applied Physics Taiyuan Normal UniversityJinzhong 030619China Institute of Theoretical Physics Shanxi UniversityTaiyuan 030006China State Key Laboratory of Quantum Optics and Quantum Optics Devices Shanxi UniversityTaiyuan 030006China Department of Astronomy Beijing Normal UniversityBeijing 100875China

Stellar structure and evolution theory is one of the bases in modern astronomy.Stellar inner structures and their evolutionary states can be precisely tested by asteroseismology,since the inner information is brought to the stellar surface by the global oscillating waves and becomes observable.For stellar evolutionary speed(i.e.,how long timescale does a star stay at a special evolution phase?),because of the insurmountable gap between the timescales of the evolutionary history of human civilization and a star,it can only be roughly tested by ensemble of stars in different evolutionary stages in most cases,and all the snapshots of these stars make up our global view of stellar evolution.The effect of stellar evolution on the structure and the corresponding global size of a pulsating star will lead to tiny period variations of its pulsation modes,which are the most valuable indicators of its evolutionary state and can be used to test the stellar evolution theory by a single star rather than ensemble of stars.Here,we report a High-AmplitudeδScuti star AE Ursae Majoris,which is located in the post main-sequence(MS)evolutionary stage and its observed linear period variation rate can be practically ascribed to its evolutionary effect.The result tests the stellar evolution theory from the pre-MS to post-MS with an unprecedented precision by a single star,and the framework can be extended to other type of pulsating stars to perform precise evolutionary asteroseismology,which aims to test the current stellar evolution theory in different evolutionary stages,discover the discrepancies between the theory and observations,and ultimately build a complete and precise stellar evolution theory to backtrack the history of each of these stars.

关键词： stars variables delta Scuti-stars evolution-stars oscillations(including pulsations)

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Urban Agglomeration Formation and Its Spatiotemporal Expansion Process in China: From the Perspective of Industrial Evolution

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Chinese Geographical Science 2020年第3期30卷 532-543页

作者： niu Fangqu YANG Xinyu WANG fang Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Col-laborative Innovation Center for Geopolitical Setting of Southwest China and Borderland Development Kunming 650500China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China School of Public Administration Inner Mongolia UniversityHohhot 010070China

Urban agglomeration research has received increasing attention in China’s national development strategies, and has become a hot topic in academic research. This study develops a theoretical framework that explores the formation mechanism and expansion process of urban agglomerations from the perspective of industrial evolution, and identifies the development issues and their causes by taking Yangtze Delta and Beijing-Tianjin-Hebei urban agglomerations as case studies. In the process of urban agglomeration formation within a free market, as has happened in Yangtze Delta region, the central city develops first, its secondary industry is then transferred to its neighboring cities, and the work division and cooperation with the neighboring cities is gradually established. However, in the 1990 s, aiming to become an international metropolis, Beijing implemented a series of administrative policies to encourage the reduction of the secondary industry and the development of the tertiary industry, before its secondary industry were fully developed and transferred to its neighboring cities. This delayed the integration process and the development of the Beijing-Tianjin-Hebei urban agglomeration. This study builds a good foundation for the construction of the theoretical system’s urban agglomeration study, and provides references for decision making in an urban agglomeration development.

关键词： urban agglomeration expansion mechanism industry Beijing-Tianjin-Hebei Yangtze Delta

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Pulsed radiofrequency alleviated neuropathic pain by down-regulating the expression of substance P in chronic constriction injury rat model

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Chinese Medical Journal 2020年第2期133卷 190-197页

作者： Jing-Ai Wang Shao-Ning niu fang Luo Department of Anesthesiology Plastic Surgery HospitalChinese Academy of Medical ScienceBeijing 100144China Department of Anesthesiology Beijing Ditan HospitalCapital Medical UniversityBeijing 100015China Department of Pain Management Beijing Tiantan HospitalCapital Medical UniversityBeijing 100050China

Background:Pulsed radiofrequency(PRF),as a non-invasive treatment of neuropathic pain(NP),has been widely administered clinically.Previous studies have shown that PRF has the potential to improve hyperalgesia in animal models of NP.However,there have been few reports to clarify whether the mechanism of PRF treatment of NP involves intervention in the expression of substance P(SP).Therefore,this study administered PRF treatment to chronic constriction injury(CCI)model rats and observed the sciatic nerve mechanical pain threshold and SP expression in the spinal cord to explore the mechanism of PRF treatment.Methods:A total of 96 Sprague-Dawley rats were randomly divided into the sham-surgery-sham-treatment group(S-S group),the sham-surgery-PRF group(S-P group),the CCI-sham-treatment group(C-S group),and the CCI-PRF group(C-P group).The C-S group and the C-P group underwent sciatic nerve CCI,while the other groups received a sham operation.At 14 days after the operation,the C-P group and the S-P group were treated with PRF for 300 s.We recorded the hindpaw withdrawal threshold(HWT)and the thermal withdrawal latency(TWL)of rats in the various groups at baseline,before treatment(0 days),and at 1,7,14,and 28 days after treatment.L4 to L6 spinal cord tissues were taken before treatment(0 days)and 1,7,14,and 28 days after treatment.The transcription and translation of SP were measured by quantitative polymerase chain reaction and Western blotting,respectively.Results:The HWT and the TWL in the C-P group 28 days after PRF treatment were significantly higher than those in the C-S group(95%confidence interval[CI]:5.84–19.50,P<0.01;95%CI:2.58–8.69,P=0.01).The expression of SP in the C-P group 28 days after PRF treatment was significantly lower than that in the C-S group(95%CI:1.17–2.48,P<0.01).Conclusions:PRF may alleviate CCI-induced NP by down-regulating the expression of SP in the spinal cord of CCI model rats.

关键词： Pulsed radiofrequency Chronic constriction injury Sciatic nerve Substance P

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Copper-catalyzed diversified annulations betweenα-diketones and alkynylα-diketones

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Chinese Chemical Letters 2022年第6期33卷 2997-3002页

作者： Xiangwen Kong fang Yu Shengtong niu Fan Gong Shuang Yang Jinggong Liu Benlong Luo Xinqiang fang State Key Laboratory of Structural Chemistry and Key Laboratory of Coal to Ethylene Glycol and Its Related TechnologyCenter for Excellence in Molecular SynthesisFujian Institute of Research on the Structure of MatterUniversity of Chinese Academy of SciencesFuzhou 350100China Pingxiang University Pingxiang 337055China Orthopedics Department Guangdong Provincial Hospital of Traditional Chinese MedicineThe Second Affiliated Hospital of Guangzhou University of Chinese MedicineGuangzhou 510120China

Copper-catalyzed divergent annulations betweenα-diketones and alkynylα-diketones have been achieved,delivering a series of highly functionalized and biologically important cis-hexahydro-2Hcyclopenta[b]furan(HCPF)and 2-hydroxydihydrofuran-3(2H)-one(HDFO)products with high levels of stereoselectivity under identical conditions.The protocol features the use of earth-abundant copper catalyst,mild conditions,shortening synthetic routes in constructing different molecular frameworks,and reducing the corresponding possible waste production.The substituents of the nucleophilicα-diketones play crucial roles in switching the reaction pathways.

关键词： Copper catalysis α-Diketones Diversified annulations Substituents-controlled reactivities Atom economy

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Hypothalamic-Pituitary-End-Organ Axes:Hormone Function in Female Patients with Major Depressive Disorder

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Neuroscience Bulletin 2021年第8期37卷 1176-1187页

作者： Yuncheng Zhu Xiaohui Wu Rubai Zhou Oliver Sie Zhiang niu fang Wang Yiru fang Division of Mood Disorders Shanghai Hongkou Mental Health CenterShanghai200083China Clinical Research Center Shanghai Mental Health CenterShanghai Jiao Tong University School of MedicineShanghai200030China Shanghai Medical College Fudan UniversityShanghai200032China Shanghai Yangpu Mental Health Center Shanghai200093China CAS Center for Excellence in Brain Science and Intelligence Technology Shanghai200031China Shanghai Key Laboratory of Psychotic Disorders Shanghai201108China

Classic hypothalamic-pituitary-end-organ feedback loops–the hypothalamic-pituitary-adrenal axis(HPAA),hypothalamic-pituitary-thyroidal axis(HPTA),and hypothalamic-pituitary-gonadal axis(HPGA)–are associated with the neuroendocrine and immune systems in major depressive disorder(MDD).Female patients with MDD present with evident neuroendocrine and immunological changes.Glucocorticoid,thyroid hormone,and reproductive steroid levels fluctuate with menstrual cycles,which might lead to glucocorticoid receptor resistance,impairment of triiodothyronine conversion,and sex hormone secretion disorders.In this review,we summarize the independent and interactive functions of these three axes in female MDD patients.The similar molecular structure of steroids implies an interrelationship between the hypothalamic-pituitary-end-organ axes and the competitive inhibitory effects at the receptor level,especially when considering the HPAA and HPGA.

关键词： Major depressive disorder Neurosecretory systems Sex steroid hormones

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Inhomogeneous strain and doping of transferred CVD-grown graphene

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Rare Metals 2022年第5期41卷 1727-1734页

作者： Yu-Ting niu fang-Zhu Qing Xue-Song Li Bo Peng National Engineering Research Center of Electromagnetic Radiation Control Materials University of Electronic Science and Technology of ChinaChengdu 611731China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 611731China School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Shenzhen Institute for Advanced Study University of Electronic Science and Technology of ChinaShenzhen 518110China

Chemical vapor deposition(CVD)-grown graphene on copper foils is subject to the Cu substrate, which affects the spatial distribution of strain and doping, thus influencing the electronic properties of graphene. However, plenty of electronic devices based on CVD-grown graphene require transfer process and the distribution of doping and strain in CVD-grown graphene transferred onto the insulating substrates remains elusive.

关键词： graphene transferred strain

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Carbon monoxide-releasing molecule-2 protects intestinal mucosal barrier function by reducing epithelial tight-junction damage in rats undergoing cardiopulmonary resuscitation

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Journal of Intensive Medicine 2022年第2期2卷 118-126页

作者： Qingsheng niu fang Liu Jun Zhang Xiaojun Yang Xiaohong Wang Department of Critical Care Medicine General Hospital of Ningxia Medical UniversityYinchuanNingxia Hui Autonomous Region 750004China Ningxia Medical University YinchuanNingxia Hui Autonomous Region 750004China Department of Critical Care Medicine Heze Second People’s HospitalHezeShandong 274000China

Background:Ischemia-reperfusion injury(IRI)to the small intestine is associated with the development of systemic inflammation and multiple organ failure after cardiopulmonary resuscitation(CPR).It has been reported that exogenous carbon monoxide(CO)reduces IRI.This study aimed to assess the effects of carbon monoxide-releasing molecule-2(CORM-2)on intestinal mucosal barrier function in rats undergoing CPR.Methods:We established a rat model of asphyxiation-induced cardiac arrest(CA)and resuscitation to study intestinal IRI,and measured the serum levels of intestinal fatty acid-binding protein.Morphological changes were investigated using light and electron microscopes.The expression levels of claudin 3(CLDN3),occludin(OCLN),zonula occludens 1(ZO-1),tumor necrosis factor-alpha(TNF-α),interleukin-10(IL-10),and nuclear factor kappa B(NF-κB)p65 were detected by western blotting.Results:Compared with the sham-operated group,histological changes and transmission electron microscopy revealed severe intestinal mucosal injury in the CPR and inactive CORM-2(iCORM-2)groups.In contrast,CORM-2 alleviated intestinal IRI.CORM-2,unlike iCORM-2,markedly decreased the Chiu’s scores(2.38±0.38 vs.4.59±0.34;P<0.05)and serum intestinal fatty acid-binding protein level(306.10±19.22 vs.585.64±119.84 pg/mL;P<0.05)compared with the CPR group.In addition,CORM-2 upregulated the expres-sion levels of tight junction proteins(CLDN3,OCLN,and ZO-1)(P<0.05)and downregulated those of IL-10,TNF-α,and NF-кB p65(P<0.05)in the ileum tissue of rats that received CPR.Conclusions:CORM-2 prevented intestinal mucosal damage as a result of IRI during CPR.The underlying protective mechanism was associated with inhibition of ischemia-reperfusion-induced changes in intestinal epithelial permeability and inflammation in intestinal tissue.

关键词： Carbon monoxide-releasing molecule-2 Cardiopulmonary resuscitation Intestinal mucosal barrier Tight junction Inflammation

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Upcycling PET in parallel with energy-saving H_(2)production via bifunctional nickel-cobalt nitride nanosheets

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Nano Research 2023年第4期16卷 4625-4633页

作者： Xuan Liu Zhongying fang Dengke Xiong Shuaiqi Gong Yanli niu Wei Chen Zuofeng Chen Shanghai Key Lab of Chemical Assessment and Sustainability School of Chemical Science and EngineeringTongji UniversityShanghai 200092China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

We describe here an electro-reforming strategy to upcycle polyethylene terephthalate(PET)waste with simultaneous hydrogen production by a bifunctional nickel-cobalt nitride nanosheets electrocatalyst.PET plastics are digested in alkaline solution giving an electrochemically active monomer ethylene glycol(EG).The introduction of Co in Co-Ni3N/carbon cloth(CC)promotes the redox behavior of Ni2+/Ni3+,which is beneficial for EG oxidation at an ultra-low potential(1.15 V vs.reversible hydrogen electrode(RHE))and breaks through the limitation of high catalytic potentials of simple Ni-based electrocatalysts(1.30 V).In PET hydrolysate with Co-Ni3N/CC couples,an integrated EG oxidation-hydrogen production system achieves a current density of 50 mA·cm^(−2)at a cell voltage of 1.46 V,which is 370 mV lower than the conventional water splitting.The in-situ Raman and Fourier transform infrared(FTIR)spectroscopies and density functional theory(DFT)calculations identify the catalytic mechanism and point to advantages of heterostructure engineering in optimizing adsorption energies and promoting catalytic activities for EG oxidation.

关键词： nickel-cobalt nitride hydrogen evolution reaction polyethylene terephthalate upcycling ethylene glycol oxidation formic acid

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