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Identification and analysis of the inlet vortex of an axial-flow pump

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Journal of Hydrodynamics 2022年第2期34卷 234-243页

作者： Wen-peng Zhang Li-jian Shi Fang-ping Tang Zhuang-zhuang Sun Ye Zhang College of Hydraulic Science and Engineering Yangzhou UniversityYangzhou225009China

Axial-flow pumps are widely employed in urban flood control and drainage pumping stations.The inlet vortex is one factor that seriously threaten the safe,stable and efficient operation of axial-flow pump units.In this paper,the vortex recognition performances of two vortex identification methods,the Q—criterion and liutex methods,are compared based on an axial-flow pump,and the interactions between the impeller and vortex are explored.A flat plate vortex generator is installed in front of the impeller to continuously induce a stable vortex.The numerical simulation results show that the liutex method can not only simultaneously identify strong and weak vortices but also reduce the influence of shear force at the sidewall.The vortex and the impeller influence each other.Under the influence of rotating blades,the vortex changes from a low frequency to the blade frequency,and the vortex significantly changes the tangential velocity inside the impeller.The accuracy of the numerical simulation results is verified by experiments on the external and internal characteristics.

关键词： Axial-flow pump inlet vortex vortex identification vortex generator numerical simulation experiment

Co-Fe quantum dots coupled with ultrathin g-C_(3)N_(4) nanosheets as efficient and stable photo-Fenton catalysts

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Rare Metals 2023年第6期42卷 1877-1887页

作者： Jia-Yu li Xin-Yu Wang jian Tian Xiao-li Zhang Feng shi School of Materials Science and Engineering Shandong University of Science and TechnologyQingdao266590China School of Materials Science and Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan250353China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450001China

The Fenton reaction has been widely used in the environmental remediation.However,the sharp decline of photo-Fenton catalysts activity under neutral conditions is still an urgent problem to be solved.This study reports a Co/Fe bimetallic oxide quantum dots-coupled g-C_(3)N_(4)nanosheets(CoFeO QDs/g-C_(3)N_(4) NSs) composites with efficient degradation of organic pollutants under neutral conditions.Under the photo-Fenton condition,rhodamine B(RhB) degradation efficiency reached 98.32% within 90min for CoFeO QDs/g-C_(3)N_(4) NSs composites.The formed heterojunction between CoFeO QDs and g-C_(3)N_(4) NSs achieves enhanced charge transfer and efficient charge separation.Co-Fe bimetals make g-C_(3)N_(4) NSs easier to excite the production of·OH by H_(2)O_(2),achieving excellent degradation efficiency and cycle stability for organic pollutants in a wide pH range.Therefore,CoFeO QDs/g-C_(3)N_(4)NSs composites can be used as efficient and stable photoFenton catalysts to degrade organic contaminants in practical applications.

关键词： Bimetallic oxide Quantum dots(QDs) gC_(3)N_(4) Wastewater treatment Photo-Fenton

Squeezing microwaves by magnetostriction

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National Science Review 2023年第5期10卷 208-214页

作者： Jie li Yi-Pu Wang jian-Qiang You shi-Yao Zhu Interdisciplinary Center of Quantum Information Zhejiang Province Key Laboratory of Quantum Technology and Deviceand State Key Laboratory of Modern Optical InstrumentationSchool of PhysicsZhejiang University

Squeezed light finds many important applications in quantum information science and quantum metrology,and has been produced in a variety of physical systems involving optical non-linear processes.Here,we show how a non-linear magnetostrictive interaction in a ferrimagnet in cavity magnomechanics can be used to reduce quantum noise of the electromagnetic field.We show optimal parameter regimes where a substantial and stationary squeezing of the microwave output field can be achieved.Realization of the scheme is within reach of current technology in cavity electromagnonics and magnomechanics.Our work provides a new and practicable approach for producing s queezed vacuum states of electromagnetic fields,and may find promising applications in quantum information processing and quantum metrology.

关键词： squeezing of quantum noise cavity magnonics magnomechanics

Recent advances in transition-metal-free C–H functionalization of imidazo[1,2-a]pyridines

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Green Synthesis and Catalysis

Green Synthesis and Catalysis 2022年第3期3卷 227-242页

作者： linlin shi Tiantian li Guang-jian Mei Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001China

Imidazo[1,2-a]pyridines are unique nitrogen-containing organic compounds with wide applications in pharma-ceuticals,natural products,material science and organometallics.Due to their significant biological and synthetic value,the construction of imidazo[1,2-a]pyridine scaffolds has been a highly intriguing research topic,and substantial progress had been made in the past decades.In this review,we aim to summarize the current advances in direct C–H functionalization of imidazo[1,2-a]pyridines under transition-metal-free conditions.For the selected examples,we focused on the design and catalytic cycle mechanism,as well as on representative outcomes and applications.

关键词： Imidazo[1,2-a]pyridines Transition metal-free Iodo-mediated Organocatalyst Oxidant-mediated Base-mediated Catalyst-free

Survey on Multi-period Mean-Variance Portfolio Selection Model

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Journal of the Operations Research Society of China 2022年第3期10卷 599-622页

作者： Xiang-Yu Cui jian-Jun Gao Xun li Yun shi School of Statistics and Management Shanghai University of Finance and EconomicsShanghai200433China School of Information Management and Engineering Shanghai University of Finance and EconomicsShanghai200433China Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina Academy of Statistics and Interdisciplinary Sciences Faculty of Economics and ManagementEast China Normal UniversityShanghai200062China

Due to the non-separability of the variance term,the dynamic mean-variance(MV)portfolio optimization problem is inherently difficult to solve by dynamic programming.li and Ng(Math Finance 10(3):387-406,2000)and Zhou and li(Appl Math Optim 42(1):19-33,2000)develop the pre-committed optimal policy for such a problem using the embedding method.Following this line of research,researchers have extensively studied the MV portfolio selection model through the inclusion of more practical investment constraints,realistic market assumptions and various financial applications.As the principle of optimality no longer holds,the pre-committed policy suffers from the time-inconsistent issue,i.e.,the optimal policy computed at the intermediate time t is not consistent with the optimal policy calculated at any time before time t.The time inconsistency of the dynamic MV model has become an important yet challenging research topic.This paper mainly focuses on the multi-period mean–variance(MMV)portfolio optimization problem,reviews the essential extensions and highlights the critical development of time-consistent policies.

关键词： Multi-period mean-variance Investment constraints Time inconsistency

Application value of biofluid-based biomarkers for the diagnosis and treatment of spinal cord injury

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Neural Regeneration Research 2022年第5期17卷 963-971页

作者： Hong-Da Wang Zhi-jian Wei Jun-Jin li shi-Qing Feng Department of Orthopedics Tianjin Medical University General HospitalTianjinChina International Science and Technology Cooperation Base of Spinal Cord Injury Tianjin Key Laboratory of Spine and Spinal CordTianjin Medical University General HospitalTianjinChina Department of Orthopedics Qilu HospitalCheeloo College of MedicineShandong UniversityJinanShandong ProvinceChina Shandong University Center for Orthopedics Cheeloo College of MedicineShandong UniversityJinanShandong ProvinceChina

Recent studies in patients with spinal cord injuries(SCIs)have confirmed the diagnostic potential of biofluid-based biomarkers,as a topic of increasing interest in relation to SCI diagnosis and treatment.This paper reviews the research progress and application prospects of recently identified SCI-related biomarkers.Many structural proteins,such as glial fibrillary acidic protein,S100-β,ubiquitin carboxy-terminal hydrolase-L1,neurofilament light,and tau protein were correlated with the diagnosis,American Spinal Injury Association Impairment Scale,and prognosis of SCI to different degrees.Inflammatory factors,including interleukin-6,interleukin-8,and tumor necrosis factorα,are also good biomarkers for the diagnosis of acute and chronic SCI,while non-coding RNAs(micro RNAs and long non-coding RNAs)also show diagnostic potential for SCI.Trace elements(Mg,Se,Cu,Zn)have been shown to be related to motor recovery and can predict motor function after SCI,while humoral markers can reflect the pathophysiological changes after SCI.These factors have the advantages of low cost,convenient sampling,and ease of dynamic tracking,but are also associated with disadvantages,including diverse influencing factors and complex level changes.Although various proteins have been verified as potential biomarkers for SCI,more convincing evidence from large clinical and prospective studies is thus required to identify the most valuable diagnostic and prognostic biomarkers for SCI.

关键词： biomarker diagnosis inflammatory cytokine motor recovery non-coding RNA prognosis spinal cord injury structural protein trace element

Generation of Leydig-like cells:approaches,characterization,and challenges

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Asian Journal of Andrology 2022年第4期24卷 335-344页

作者： Zhao-Hui li Jun-Dong Lu shi-Jun li Hao-lin Chen Zhi-jian Su Guangdong Provincial Key Laboratory of Bioengineering Medicine Department of Cell BiologyJinan UniversityGuangzhou 510632China lnstitute of life Sciences Wenzhou UniversityWenzhou 325035China Department of Gynecology and Obstetrics The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical UniversityWenzhou 325027China National Engineering Research Center of Genetic Medicine Jinan UniversityGuangzhou 510632China

Testosterone production by Leydig cells(LCs)plays a crucial role in male reproduction.The functional degeneration of LCs can cause testosterone deficiency,ultimately resulting in primary male hypogonadism.Transplantation of exogenous LCs with the ability to produce testosterone in response to the regulation of the hypothalamus-pituitary-gonad axis could be a promising alternative option to treat male primary hypogonadism.Recent studies have shown that it is possible to generate Leydig-like cells from stem cells by various approaches.In addition,somatic cells,such as embryonic or adult fibroblasts,have also been successfully reprogrammed into Leydig-like cells.In this review,we summarized the recent advances in the generation of Leydig-like cells,with an emphasis on comparing the effectiveness and safety of different protocols used and the cells generated.By further analyzing the characteristics of Leydig-like cells generated from fibroblasts based on small signaling molecules and regulatory factors,we found that although the cells may produce testosterone,they are significantly different from real LCs.For future in vivo applications,it is important that the steroidogenic cells generated be evaluated not only for their steroidogenic functions but also for their overall cell metabolic state by proteomics or transcriptomic tools.

关键词： fibroblasts hypogonadism Leydig-like cells reprogramming stem cells

High-efficiency nonlocal reflection-type vortex beam generation based on bound states in the continuum

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National Science Review 2023年第5期10卷 201-207页

作者： Tongyu li Jiajun Wang Wenjie Zhang Xinhao Wang Wenzhe liu Lei shi jian Zi State Key Laboratory of Surface Physics Key Laboratory of Micro-and Nano-Photonic Structures (Ministry of Education) and Department of PhysicsFudan University Department of Physics The Hong Kong University of Science and Technology

Momentum-space polarization vortices centered at symmetry-protected bound states in the continuum of a periodic structure,e.***.photonic crystal slab,provide a novel nonlocal approach to generate vortex beams.This approach enjoys a great convenience of no precise alignment requirements,although the generation efficiency of the nonlocal generators requires further optimization before the practical application.In this work,we propose a temporal-coupled-mode-theory-based guideline for high-efficiency nonlocal reflection-type vortex generator design.The conversion efficiency of the vortex beam is found to be limited by the ratio of the radiative loss to the intrinsic absorption in practical systems.To increase this ratio through mode selection and structure design,the photonic crystal slabs are theoretically designed and experimentally characterized,showing a maximum on-resonance conversion efficiency of up to 86%.Combining high efficiency with simple fabrication and no re quirement for precise alignment,reflection-type photonic crystal slabs could offer a new and competitive way to generate vortex beams flexibly.

关键词： photonic crystal slab vortex beam bound states in the continuum

Fragment spatial distribution of prismatic casing under internal explosive loading

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Defence Technology（防务技术） 2020年第4期16卷 910-921页

作者： Tianbao Ma Xinwei shi jian li jianguo Ning State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.

关键词： Fragment spatial distribution Prismatic casing Internal explosive loading Numerical fitting formula Marker-point weighted method