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Miura origami based reconfigurable polarization converter for multifunctional control of electromagnetic waves

Photonics Research 2024年第3期12卷 581-586页

作者： ZHIBIAO ZHU yongfeng li ZHE QIN liXIN JIANG WENJIE WANG HONGYA CHEN JIAFU WANG YONGQIANG PANG SHAOBO QU Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices Air Force Engineering UniversityXi’an 710051China School of Electronic Science and Engineering Xi’an Jiaotong UniversityXi’an 710049China

Polarization is one of the basic characteristics of electromagnetic(EM)waves,and its flexible control is very important in many practical applications.At present,most of the multifunction polarization metasurfaces are electrically tunable based on PIN and varactor diodes,which are easy to operate and have strong real-time performance.However,there are still some problems in them,such as few degrees of freedom of planar structure control,complex circuit,bulky sample,and high cost.In view of these shortcomings,this paper proposes a Miura origami based reconfigurable polarization conversion metasurface for multifunctional control of EM waves.The interaction between the electric dipoles is changed by adjusting the folding angleθ,thereby tuning the operating frequency of the polarization conversion and the polarization state of the reflected wave.This mechanical control method brings more degrees of freedom to manipulate EM waves.And the processed sample is with lightweight and low cost.To verify the performance of the proposed origami polarization converter,a Miura origami structure loaded with metal split rings is designed and fabricated.The operating frequency of the structure can be tuned in different folding states.In addition,by controlling the folding angleθ,linear-to-linear and linear-to-circular polarization converters can be realized at different folding states.The proposed Miura origami polarization conversion metasurface provides a new idea for reconfigurable linear polarization conversion and multifunctional devices.

关键词： polarization reconfigurable tuning

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Synergistic extraction of rare earth elements and alumina from coal fly ash by potassium pyrosulfate

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Journal of Rare Earths 2024年第4期42卷 749-758页

作者： Jingjing Zou Yiping Sun Chunbin Guo Daye Chen Yonghong Song yongfeng Wu Zhaotianhui li Department of Environment Science and Engineering Liaoning Technical UniversityFuxin23000China Department of Materials Science and Engineering Liaoning Technical UniversityFuxin123000 China Technology Research and Development Department Chinese Institute of Coal ScienceBeijing100013China Shenhua Zhungeer Energy and Resource Comprehensive Development Co. Ltd.Erdos10300China liaoning Yingguan High-tech Ceramic Co. Ltd.Jinzhou121213China

Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other drawbacks.To address these problems,in this study,we examined the coextraction of REEs and Al_(2)O_(3)from two types of Al_(2)O_(3)-rich CFA,pulverized CFA(PCFA)and circulating fluidized bed fly ash(CFBFA)using low-temperature calcination in the presence of K_(2)S_(2)O_(7).The total REEs,heavy REEs(HREEs),and light REEs(LREEs)extraction efficiencies were determined using different K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios and calcination temperatures and correlated with the Al_(2)O_(3) extraction efficiency using Pearson correlation coefficient analysis.The REEs are concentrated within CFA particles encapsulated in an aluminosilicate glass phase,and the REEs extraction efficiency is related to the form of Al in CFA.The extraction efficiencies of Al_(2)O_(3) and REEs increase as the K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratio and calcination temperature increase,and the extraction selectivity of the more industrially valuable HREEs from CFBFA is higher.At high K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios,the extraction of REEs from PCFA is more efficient than that from CFBFA with the regeneration of the highly active Al-O-Si bonds in CFBFA.The Al_(2)O_(3) extraction efficiencies of PCFA as well as CFBFA correlate strongly with the total REEs,HREEs,and LREEs extraction efficiencies.The developed extraction technology has the potential to promote CFA valorization and expand REEs resources,thus mitigating the bottlenecks of REEs procurement.

关键词： Rare earths Alumina Coal fly ash Potassium pyrosulfate Calcination Extraction

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N-doped carbon nanotube encapsulated nZVI as a high-performance bifunctional catalyst for oxidative desulfurization

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Particuology 2023年第10期81卷 109-118页

作者： Ge Zhang Fan Yang Wang Yang yongfeng li State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijingChina Beijing NAURA Vacuum Technology Co. LtdBeijingChina

Great efforts have been made to remove sulfur from fossil fuels to protect the environment.We proposed synthesis of high efficiency oxidation desulfurization(ODS)catalysts by encapsulating nano zero valent iron(nZVI)in self-catalyzed carbon nanotubes.The synthetic strategy features facile hydrothermal and pyrolysis process.The specific surface area,pore structure,and microstructure of the catalysts were characterized by series techniques,and the catalytic ability was evaluated by the reduction of sulfur after oxidation and reflux-extraction.The optimized nZVI@CNT catalyst exhibits outstanding catalytic performance(within 120 min,the oxidative removal rate of DBT reached 96%)and enhanced stability(a 80%retention of initial performance after six cycles.),revealing the effective optimization and modulation between carbon nanotubes and iron particles.This excellent ODS activity originated from the defects of N-doped nanotubes as well as excellent particle dispersion and material transport capacity,which excites highly active free radicals with the assistance of H_(2)O_(2).In addition,the unique two-dimensional tube channel and mesoporous structure promoted the diffusion and transfer of reactants and electrons,leading to high density of active sites.The different experimental conditions confirmed that the material is a bifunctional catalyst integrating adsorption and catalysis.This work provides an creative ideas for the rational design and synthesis of advanced ODS catalysts for fuel oil.

关键词： Carbon nanotubes Oxidative desulfurization Dispersion Nanoscale zero valent iron

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Metal size effects over metal/zeolite bifunctional catalysts in the selective hydroalkylation of benzene

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Frontiers of Chemical Science and Engineering 2024年第4期18卷 107-114页

作者： Junjie li Chuang liu Zhenlong Jia Yingchun Ye Dawei Lan Wei Meng Jianqiang Wang Zhendong Wang yongfeng Hu Weimin Yang State Key Laboratory of Green Chemical Engineering and Industrial Catalysis Sinopec Shanghai Research Institute of Petrochemical Technology Co.Ltd.Shanghai 201208China School of Chemical Engineering East China University of Science and TechnologyShanghai 200237China

Bifunctional metal/zeolite materials are some of the most suitable catalysts for the direct hydroalkylation of benzene to cyclohexylbenzene.The overall catalytic performance of this reaction is strongly influenced by the hydrogenation,which is dependent on the metal sizes.Thus,systematically investigating the metal size effects in the hydroalkylation of benzene is essential.In this work,we successfully synthesized Ru and Pd nanoparticles on Sinopec Composition Materials No.1 zeolite with various metal sizes.We demonstrated the size-dependent catalytic activity of zeolite-supported Ru and Pd catalysts in the hydroalkylation of benzene,which can be attributed to the size-induced hydrogen spillover capability differences.Our work presents new insights into the hydroalkylation reaction and may open up a new avenue for the smart design of advanced metal/zeolite bi-functional catalysts.

关键词： size effects bifunctional catalysts metal/zeolite hydroalkylation

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Evaluation of Holstein cows with different tongue‑rolling frequencies:stress immunity,rumen environment and general behavioural activity

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Journal of Animal Science and Biotechnology 2023年第6期14卷 2686-2700页

作者： Fuyu Sun Xiaoyang Chen yongfeng li Guangyong Zhao Xianhong Gu State Key Laboratory of Animal Nutrition Institute of Animal ScienceChinese Academy of Agricultural SciencesHaidian DistrictNo.2 Yuanmingyuan West RoadBeijingChina. College of Animal Science and Technology China Agricultural UniversityHaidian DistrictNo.2 Yuanmingyuan West RoadBeijingChina. Agricultural Information Institute Chinese Academy of Agriculture SciencesHaidian DistrictNo.12 Zhongguancun South StreetBeijingChina

Background The tongue-rolling behaviour of cows is regarded as an outward sign of stressed animals in a low welfare status.The primary aim of this observational study was to evaluate the association between the frequency of tongue-rolling behaviour and its physiological function.The secondary aim was to explore the relationship between general activities and the frequency of tongue-rolling behaviour of cows.A total of 126 scan sampling behavioural observations were collected over 7 d on 348 Holstein cows with the same lactation stage in the same barn.The tongue-rolling frequency was defined as the number of tongue-rolling observations as a percentage to the total observations per individual cow.According to their tongue-rolling frequency,the cows were grouped into the CON(no tongue-rolling),LT(frequency 1%),MT(frequency 5%),and HT(frequency 10%)groups.Six cows from each group were randomly selected for sampling.Serum samples,rumen fluid,milk yield,and background infor-mation were collected.The general behaviour data during 72 continuous hours of dairy cows,including eating time,rumination time,food time(eating time+rumination time),and lying time,were recorded by the collar sensor.Results Cortisol(P=0.012),γ-hydroxybutyric acid(P=0.008),epinephrine(P=0.030),and dopamine(P=0.047)levels were significantly higher in tongue-rolling groups than in the CON group.Cortisol levels and tongue-rolling frequency had a moderate positive correlation(linearly r=0.363).With the increase in tongue-rolling frequency,the rumen pH decreased first and then increased(P=0.013),comparing to the CON group.HT cows had significantly less food time than CON cows(P=0.035).The frequency of tongue-rolling had a moderate negative relationship with rumination time(r=-0.384)and food time(r=-0.492).Conclusions The tongue-rolling behaviour is considered as a passive coping mechanism,as the stress response in cows with high tongue-rolling frequency increased.Food intake and rumination activities were all closely related to the occurrence of tongue-r

关键词： General activity Holstein cow Rumen fermentation Stress immunity Tongue rolling

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A STOCHASTIC TRUST-REGION FRAMEWORK FOR POliCY OPTIMIZATION

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Journal of Computational Mathematics 2022年第6期40卷 1004-1030页

作者： Mingming Zhao yongfeng li Zaiwen Wen Beijing International Center for Mathematical Research Peking UniversityBeijing 100871China

In this paper,we study a few challenging theoretical and numerical issues on the well known trust region policy optimization for deep reinforcement learning.The goal is to find a policy that maximizes the total expected reward when the agent acts according to the policy.The trust region subproblem is constructed with a surrogate function coherent to the total expected reward and a general distance constraint around the latest policy.We solve the subproblem using a preconditioned stochastic gradient method with a line search scheme to ensure that each step promotes the model function and stays in the trust region.To overcome the bias caused by sampling to the function estimations under the random settings,we add the empirical standard deviation of the total expected reward to the predicted increase in a ratio in order to update the trust region radius and decide whether the trial point is accepted.Moreover,for a Gaussian policy which is commonly used for continuous action space,the maximization with respect to the mean and covariance is performed separately to control the entropy loss.Our theoretical analysis shows that the deterministic version of the proposed algorithm tends to generate a monotonic improvement of the total expected reward and the global convergence is guaranteed under moderate assumptions.Comparisons with the state-of-the–art methods demonstrate the effectiveness and robustness of our method over robotic controls and game playings from OpenAI Gym.

关键词： Deep reinforcement learning Stochastic trust region method Policy optimization Global convergence Entropy control

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High mass loading NiCo_(2)O_(4) with shell-nanosheet/core-nanocage hierarchical structure for high-rate solid-state hybrid supercapacitors

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Green Energy & Environment 2022年第4期7卷 723-733页

作者： Wang Yang liqiang Hou Peng Wang Yun li Rui li Bo Jiang Fan Yang yongfeng li State Key Laboratory of Heavy Oil Processing China University of Petroleum(Beijing)Changping102249China

Rational design of advanced structure for transition metal oxides(TMOs) is attractive for achieving high-performance supercapacitors.However, it is hampered by sluggish reaction kinetics, low mass loading, and volume change upon cycling. Herein, hierarchical Ni Co_(2)O_(4) architectures with 2D-nanosheets-shell and 3D-nanocages-core(2D/3D h-NCO) are directly assembled on nickel foam via a facile one-step way.The 2D nanosheets are in-situ generated from the self-evolution of initial NCO nanospheres. This 2D/3D hierarchical structures ensure fast ion/electron transport and maintain the structural integrity to buffer the volume expansion. The 2D/3D h-NCO electrode with an ultrahigh mass loading(30 mg cm^(-2)) achieves a high areal capacity of 4.65 C cm^(-2)(equivalent to 1.29 mAh cm^(-2)) at a current density of 4 mA cm^(-2), and retains 3.7 C cm^(-2) even at 50 mA cm^(-2). Furthermore, the assembled solid-state hybrid supercapacitor yields a high volumetric energy density of 4.25 mWh cm^(-3) at a power density of 39.3 mW cm^(-3), with a high capacity retention of 92.4% after 5000 cycles. Therefore, this work provides a new insight to constuct hierarchical electrodes for energy storage application.

关键词： Transition-metal oxides Hierarchical structure High mass loading Free-standing Supercapacitors

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Targeted anti-cancer therapy: Co-delivery of VEGF siRNA and Phenethyl isothiocyanate (PEITC) via cRGD-modified lipid nanoparticles for enhanced anti-angiogenic efficacy

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Asian Journal of Pharmaceutical Sciences 2024年第2期19卷 170-187页

作者： Bao li Haoran Niu Xiaoyun Zhao Xiaoyu Huang Yu Ding Ke Dang Tianzhi Yang yongfeng Chen Jizhuang Ma Xiaohong liu Keda Zhang Huichao Xie Pingtian Ding School of Pharmacy Shenyang Pharmaceutical UniversityShenyang 110016China School of life Science and Biopharmaceutics Shenyang Pharmaceutical University Shenyang 110016 China Department of Basic Pharmaceutical Sciences School of Pharmacy Husson University Bangor ME 04401USA College of Pharmacy Shenzhen Technology UniversityShenzhen 518118China

Anti-tumor angiogenesis therapy, targeting the suppression of blood vessel growth in tumors, presents a potent approach in the battle against cancer. Traditional therapies have primarily concentrated on single-target techniques, with a specific emphasis on targeting the vascular endothelial growth factor, but have not reached ideal therapeutic efficacy. In response to this issue, our study introduced a novel nanoparticle system known as CS-siRNA/PEITC&L-cRGD NPs. These chitosan-based nanoparticles have been recognized for their excellent biocompatibility and ability to deliver genes. To enhance their targeted delivery capability, they were combined with a cyclic RGD peptide (cRGD). Targeted co-delivery of gene and chemotherapeutic agents was achieved through the use of a negatively charged lipid shell and cRGD, which possesses high affinity for integrin αvβ3 overexpressed in tumor cells and neovasculature. In this multifaceted approach, co-delivery of VEGF siRNA and phenethyl isothiocyanate (PEITC) was employed to target both tumor vascular endothelial cells and tumor cells simultaneously. The co-delivery of VEGF siRNA and PEITC could achieve precise silencing of VEGF, inhibit the accumulation of HIF-1α under hypoxic conditions, and induce apoptosis in tumor cells. In summary, we have successfully developed a nanoparticle delivery platform that utilizes a dual mechanism of action of anti-tumor angiogenesis and pro-tumor apoptosis, which provides a robust and potent strategy for the delivery of anti-cancer therapeutics.

关键词： Anti-angiogenesis Tumor apoptosis Nanoparticles VEGF siRNA Hypoxia inducible factor(HIF)-1 protein Phenethyl isothi ocyanate(PEITC)

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Electrochemical synthesis of Ni doped carbon quantum dots for simultaneous fluorometric determination of Fe^(3+)and Cu^(2+)ion facilely

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Green Chemical Engineering 2023年第1期4卷 115-122页

作者： Siyuan Sun Yang Sun Fan Yang Sai Che Xiaoyun Zhang Ge Zhang yongfeng li State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China

A novel Ni doped carbon quantum dots(Ni-CQDs)fluorescence probe was synthesized by facile electrolysis of monoatomic Ni dispersed porous carbon(Ni–N–C).The obtained Ni-CQDs showed a high quantum yield of 6.3%with the strongest excitation and emission peaks of 360 nm and 460 nm,and maintained over 90%of the maximum fluorescence intensity in a wide p H range of 3–12.The metal ions detectability of Ni-CQDs was enhanced by Ni doping and functional groups modification,and the rapid and selective detection of Fe^(3+)and Cu^(2+)ions was achieved with Ni-CQDs through dynamic and static quenching mechanism,respectively.On one hand,the energy band gap of Ni-CQDs was regulated by Ni doping,so that excited electrons in Ni-CQDs were able to transfer to Fe^(3+)easily.On the other hand,the abundant functional groups promoted the generation of static quenching complexation between Cu^(2+)and Ni-CQDs.In metal ions detection,the linear quantitation range of Fe^(3+)and Cu^(2+)were 100–1000μM(R^(2)=0.9955)and 300–900μM(R^(2)=0.9978),respectively.The limits of detection(LOD)were calculated as 10.17 and 7.88μM,respectively.Moreover,the fluorescence quenched by Cu^(2+)could be recovered by EDTA2-due to the destruction of the static quenching complexation.In this way,NiCQDs showed the ability to identify the two metal ions to a certain degree under the condition of Fe^(3+)and Cu^(2+)coexistent.This work paves the way of facile multiple metal ion detection with high sensitivity.

关键词： Electrolysis Ni doped CQDs Fe^(3+)detection Cu^(2+)detection Ions distinction

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Tailoring circular dichroism via the Born-Kuhn model for meta-holograms

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Science China(Physics,Mechanics & Astronomy) 2022年第10期65卷 83-92页

作者： He Wang Hongqiang Zhou Tianhao li Zhe Qin Chenchen li Xin li yongfeng li Jieqiu Zhang Shaobo Qu lingling Huang Department of Basic Sciences Air Force Engineering UniversityXi’an 710051China Beijing Engineering Research Center of Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Department of Physics and Optoelectronics Faculty of ScienceBeijing University of TechnologyBeijing 100124China

Chirality, as one of the ubiquitous properties in nature, has aroused striking attention in the fields of physics and materials sciences. For tailoring of light with more degree of freedom, circular dichroism has been considered as the auxiliary dimension to improving such an issue. Inspired by the Born-Kuhn plasmonic oscillation model, we demonstrate and discuss a chiral resonator to reveal reverse circular dichroism within two separate frequency bands in the microwave regime. The underlying physical mechanisms of bonding and anti-bounding modes are analyzed via transmission/reflection spectra and surface current distributions for different chiral enantiomers. To leverage the proposed paradigm to the application levels, especially for metaholography, we conduct the numerical simulation and experimental demonstration of two proofs of principles. Based on the Pancharatnam-Berry phase/amplitude modulation and complex-amplitude manipulation, respectively, the meta-holograms with independent targets of reconstructing images in full-space and reflected regions are achieved. Significantly, our paradigm may promise further applications in spin-controlled meta-devices for image processing, information encryption, anti-counterfeiting,remote sensing, and radar systems.

关键词： circular dichroism Born-Kuhn model meta-hologram electromagnetic manipulation

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