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Solid-conversion synthesis of three-dimensionally ordered mesoporous ZSM-5 catalysts for the methanol-to-propylene reaction

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Frontiers of Chemical Science and Engineering 2024年第8期18卷 111-122页

作者： Weilong Chun chenbiao yang Xu Wang xin yang Huiyong chen School of Chemical Engineering Northwest UniversityXi’an 710069China International Science&Technology Cooperation Base for Clean Utilization of Hydrocarbon Resources Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei EnergyCollaborative Innovation Center for Development of Energy and Chemical Industry in Northern ShaanxiNorthwest UniversityXi’an 710069China

A facile synthesis of hierarchical ZSM-5 with the three-dimensionally ordered mesoporosity(3DOm ZSM-5)was achieved by solid conversion(SC)of SiO_(2)colloidal crystals to high-crystalline *** products of 3DZ5_S/C and 3DZ5_S,which were severally transformed from the carbon-padded SiO_(2)colloidal crystals and the initial SiO_(2)colloidal crystals,exhibited not only a similar ordered structure and acidity but also higher crystallinity and more balanced meso-/micropore combination in comparison with 3DZ5_C obtained by the conventional confined space crystallization *** three synthesized 3DZ5 catalysts showed improved methanol-to-propylene performance than the commercially microporous ZSM-5(CZ5),embodied in five times longer lifetime,higher propylene selectivity and S_(propylene)/S_(ethylene) ratio(P/E),and superior coke toleration with lower formation rate of coke(R_(coke)).Moreover,the 3DZ5_S catalyst in situ converted from SiO_(2)colloidal crystals presented the highest selectivities of propylene(42.51%)and light olefins(74.6%)among all three 3DZ5 *** high efficiency in synthesis and in situ utilization of SiO_(2)colloidal crystals demonstrate the proposed SC strategy to be more efficiently and eco-friendly for the high-yield production of not only 3DOm ZSM-5 but also other types of hierarchical zeolites.

关键词： hierarchical zeolite three-dimensionally ordered mesoporosity ZSM-5 solid conversion methanol-to-propylene

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Ir single atoms on NiFeZn-LDH matrix for exceptional oxygen evolution reaction

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Nano Research 2024年第8期17卷 7039-7044页

作者： Muhammad Israr Muhammad Humayun Jiaqi Zhang Khadim Shah xin Tan chen chen Yadong Li Department of Chemistry Tsinghua UniversityBeijing 100084China Energy Water and Environment LabCollege of Humanities and SciencePrince Sultan UniversityRiyadh11586Saudi Arabia

To address the sluggish kinetics of the oxygen evolution reaction(OER),a potential approach is to rationally design and fabricate extremely effective single atom catalysts(SACs).Using an appropriate matrix to stabilize single-atom active centers with optimal geometric and electronic structures is crucial for enhancing catalytic ***,we report the design and fabrication of Ir single atoms on NiFeZn layered double hydroxide(Ir-SAC/NiFeZn-LDH)electrocatalyst for highly efficient and stable *** is investigated that the NiFeZn support exhibits abundant defect sites and unsaturated coordination *** sites function to anchor and stabilize single Ir single atoms on the *** strong synergetic electronic interaction between the Ir single atoms and the NiFeZn matrix resulted in remarkable OER performance of the as-fabricated Ir-SAC/NiFeZn *** a loading Ir content of 1.09 wt.%,this catalyst demonstrates a highly stable OER activity,with an overpotential of 196 mV at 10 mA·cm^(−2) and a small Tafel slope of 35 mV·dec^(−1) for the OER in a 1 M KOH *** results significantly surpass the performance of the commercially available IrO_(2) catalyst.

关键词： Ir single atoms layered double hydroxides rational design geometric optimization oxygen evolution reaction

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The variation of microbiological characteristics in surface waters during persistent precipitation

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Frontiers of Environmental Science & Engineering 2024年第9期18卷 67-78页

作者： xinyan Xiao chenlan chen Haoran Li Lihua Li xin Yu College of the Environment&Ecology Xiamen UniversityXiamen 361102China Fujian Key Laboratory of Coastal Pollution Prevention and Control Xiamen UniversityXiamen 361102China

Climate change leads to an increase in both the frequency and intensity of extreme *** runoff generated by extreme precipitation has a significant impact on ***,the impact of persistent precipitation on surface water quality is easy to neglect,due to its prolonged duration and lower-intensity *** study established eight sampling points within selected surface waters to observe the variation of microbial characteristics in a typical persistence precipitation *** primary difference between Furong Lake(FL)and chengqian Reservoir(CR)was:the concentrations of dissolved organic carbon(DOC)were 21.3±0.7 and 8.3±1.5 mg/L in FL and CR,*** concentrations of R2A culturable bacteria and coliforms were 10^(4.57)and 10^(1.58)colony-forming units(CFU)/mL in FL,and were 10^(5.46)and 10^(2.64)CFU/mL in CR,*** precipitation,the maximum increase concentrations of R2A,NA culturable bacteria,and coliforms were 10^(0.75),10^(1.30),and 10^(2.27)CFU/mL in FL,***,microbial concentration and rainfall did not increase simultaneously,and a delay phenomenon was observed in the increasing microbial *** analyzing the concentration change trends and correlation of various water quality indicators during persistent precipitation,the significant correlation between the DOC concentration and the changes in the dominant species of microbial community structure was found in this study(p<0.05).For example,as the DOC concentration declined,the abundance of hgcl_clade and CL500-29_marine_group ***,although persistent precipitation might not obviously alter the water quality visibly,it could still pose potential microbial risks.

关键词： Rainfall Dissolved organic carbon Culturable bacteria Water quality Microbial community structure Climate change

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Machine learning-driven optimization of plasma-catalytic dry reforming of methane

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Journal of Energy Chemistry 2024年第9期96卷 153-163页

作者： Yuxiang Cai Danhua Mei yanzhen chen Annemie Bogaerts xin Tu Department of Electrical Engineering and Electronics University of LiverpoolLiverpool L693GJUK Research Group PLASMANT Department of ChemistryUniversity of AntwerpUniversiteitsplein 1BE-2610 Wilrijk-AntwerpBelgium College of Electrical Engineering and Control Science Nanjing Tech UniversityNanjing 211816JiangsuChina

This study investigates the dry reformation of methane(DRM)over Ni/Al_(2)O_(3)catalysts in a dielectric barrier discharge(DBD)non-thermal plasma reactor.A novel hybrid machine learning(ML)model is developed to optimize the plasma-catalytic DRM reaction with limited experimental *** address the non-linear and complex nature of the plasma-catalytic DRM process,the hybrid ML model integrates three well-established algorithms:regression trees,support vector regression,and artificial neural networks.A genetic algorithm(GA)is then used to optimize the hyperparameters of each algorithm within the hybrid ML *** ML model achieved excellent agreement with the experimental data,demonstrating its efficacy in accurately predicting and optimizing the DRM *** model was subsequently used to investigate the impact of various operating parameters on the plasma-catalytic DRM *** found that the optimal discharge power(20 W),CO_(2)/CH_(4)molar ratio(1.5),and Ni loading(7.8 wt%)resulted in the maximum energy yield at a total flow rate of∼51 mL/***,we investigated the relative significance of each operating parameter on the performance of the plasma-catalytic DRM *** results show that the total flow rate had the greatest influence on the conversion,with a significance exceeding 35%for each output,while the Ni loading had the least impact on the overall reaction *** hybrid model demonstrates a remarkable ability to extract valuable insights from limited datasets,enabling the development and optimization of more efficient and selective plasma-catalytic chemical processes.

关键词： Plasma catalysis Machine learning Process optimization Dry reforming of methane Syngas production

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Underdetermined direction of arrival estimation with nonuniform linear motion sampling based on a small unmanned aerial vehicle platform

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Defence Technology（防务技术） 2024年第3期33卷 352-363页

作者： xinwei Wang Xiaopeng yan Tai An Qile chen Dingkun Huang Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China

Uniform linear array(ULA)radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles(UAVs).In practice,a ULA's multi-target direction of arrival(DOA)estimation performance suffers from significant performance degradation owing to the limited number of physical *** improve the underdetermined DOA estimation performance of a ULA radar mounted on a small UAV platform,we propose a nonuniform linear motion sampling underdetermined DOA estimation *** the motion of the UAV platform,the echo signal is sampled at different ***,according to the concept of difference co-array,a virtual ULA with multiple array elements and a large aperture is synthesized to increase the degrees of freedom(DOFs).Through position analysis of the original and motion arrays,we propose a nonuniform linear motion sampling method based on ULA for determining the optimal *** the condition of no increase in the aperture of the physical array,the proposed method obtains a high DOF with fewer sampling runs and greatly improves the underdetermined DOA estimation performance of *** results of numerical simulations conducted herein verify the superior performance of the proposed method.

关键词： Unmanned aerial vehicle(UAV) Uniform linear array(ULA) Direction of arrival(DOA) Difference co-array Nonuniform linear motion sampling method

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Large porewater exchange reshapes saltmarsh carbon and greenhouse gas budgets on local and global scales

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Science China Earth Sciences 2024年第7期67卷 2195-2209页

作者： Xiaogang chen Isaac RSANTOS Lucheng ZHAN Yu yan YAU yan ZHANG Ling LI Key Laboratory of Coastal Environment and Resources of Zhejiang Province School of EngineeringWestlake UniversityHangzhou 310024China Department of Marine Sciences University of GothenburgGothenburg 41319Sweden College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210024China

Saltmarshes are carbon-rich ecosystems that play a role in climate regulation by efficiently sequestrating atmospheric CO_(2).Climate change is a major threat to saltmarshes and will impact saltmarsh carbon ***,porewater-derived carbon outwelling emerges as a crucial pathway for carbon sequestration,but it has been largely overlooked in ***,we assessed the drivers of dissolved carbon exports and greenhouse gas emissions in a saltmarsh and placed those observations into a global *** our study site,porewater exchange(PEX)was the major process controlling dissolved carbon and greenhouse gas *** our results with 33 other studies in saltmarshes worldwide,porewater-derived carbon fluxes were equivalent to~48% of average global saltmarsh primary productivity and 2.2 times greater than global organic carbon ***,our local observations and global upscaling demonstrate the major role played by PEX in saltmarsh carbon *** part of dissolved inorganic carbon returns to the atmosphere as CO_(2),the remaining bicarbonate fraction is stored in the ocean over long time *** findings strengthen global blue carbon assessments and build arguments for the use of saltmarshes as nature-based solutions for global climate change.

关键词： Coastal carbon Global carbon budget Carbon neutrality Nature-based solutions Coastal wetlands Submarine groundwater discharge

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Detecting compromised accounts caused by phone number recycling on e-commerce platforms: taking Meituan as an example

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Frontiers of Information Technology & Electronic Engineering 2024年第8期25卷 1077-1095页

作者： Min GAO Shutong chen yangbo GAO Zhenhua ZHANG Yu chen Yupeng LI Qiongzan YE xin WANG yang chen School of Computer Science Fudan UniversityShanghai 200438China Shanghai Key Lab of Intelligent Information Processing Fudan UniversityShanghai 200438China Meituan Beijing 100005China Department of Interactive Media Hong Kong Baptist UniversityHong Kong 999077China

Phone number recycling(PNR)refers to the event wherein a mobile operator collects a disconnected number and reassigns it to a new *** has posed a threat to the reliability of the existing authentication solution for e-commerce ***,a new owner of a reassigned number can access the application account with which the number is associated,and may perform fraudulent *** solutions that employ a reassigned number database from mobile operators are costly for e-commerce platforms with large-scale ***,alternative solutions that depend on only the information of the applications are *** this work,we study the problem of detecting accounts that have been compromised owing to the reassignment of phone *** analysis on Meituan's real-world dataset shows that compromised accounts have unique statistical features and temporal *** on the observations,we propose a novel model called temporal pattern and statistical feature fusion model(TSF)to tackle the problem,which integrates a temporal pattern encoder and a statistical feature encoder to capture behavioral evolutionary interaction and significant operation *** experiments on the Meituan and IEEE-CIS datasets show that TSF significantly outperforms the baselines,demonstrating its effectiveness in detecting compromised accounts due to reassigned numbers.

关键词： Phone number recycling Neural networks E-commerce Compromised account detection

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Microstructure and mechanical properties of a cast TRIP-assisted multiphase stainless steel

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China Foundry 2024年第3期21卷 221-228页

作者： Meng-xin Wang Zi-xiang Wu Jing-yu He Xiang chen School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China

Stainless steels are used in a wide range of complex environments due to their excellent corrosion *** stainless steels can offer an excellent combination of strength,toughness and corrosion resistance due to the coexistence of different *** microstructure and mechanical properties of a novel cast multiphase stainless steel,composed of martensite,ferrite,and austenite,were investigated following appropriate heat treatment processes:solution treatment at 1,050℃ for 0.5 h followed by water quenching to room temperature,and aging treatment at 500℃ for 4 h followed by water quenching to room *** show reversed austenite is formed by diffusion of Ni element during aging process,and the enrichment of Ni atoms directly determines the mechanical stability of *** austenite with a lower Ni content undergoes a martensitic transformation during plastic *** tensile strength of the specimen exceeds 1,100 MPa and the elongation exceeds 24%after solid solution,and further increases to 1,247 MPa and 25%after aging *** enhancement is due to the TRIP effect of austenite and the precipitation of the nanoscale G-phase pinning dislocations in ferrite and martensite.

关键词： multiphase stainless steel mechanical properties TRIP effect reversed austenite G-phase

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Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

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World Journal of Stem Cells 2024年第6期16卷 708-727页

作者： Lei-Mei Xu xin-xin Yu Ning Zhang Yi-Song chen Department of Gynecology Obstetrics and Gynecology Hospital of Fudan UniversityShanghai 200011China Department of Gynecology Shanghai Key Laboratory of Female Reproductive Endocrine-related DiseasesShanghai 200011China

BACKGROUND Pelvic organ prolapse(POP)involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity,and vaginal structure is an essential *** POP,the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and *** intricate etiology of POP and the prohibition of trans-vaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy *** umbilical cord mesenchymal stromal cells(hucMSCs)present limitations,but their exosomes(hucMSC-Exo)are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix *** inflammation in POP group fibroblasts,stimulated primary fibroblast growth,and elevated collagen I(Col1)production in ***-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11(MMP11)*** HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in *** miRNAs in hucMSC-Exo targeted and downregulated MMP11 ***-Exo-based therapy may be ideal for safely and effectively treating POP.

关键词： Pelvic organ prolapse Exosomes Fibroblasts Human umbilical cord mesenchymal stromal cells Extracellular matrix Collagen I

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Microphase Separation of Semiflexible Ring Diblock Copolymers

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Chinese Journal of Polymer Science 2024年第2期42卷 267-276,I0011页

作者： Dan-yan Qin Sheng-Da Zhao Zhi-xin Liu Jing Zhang xing-Hua Zhang School of Physical Science and Engineering Beijing Jiaotong UniversityBeijing100044China

Aiming at the difficult problem of solving the conformation statistics of complex polymers, this study presents a novel and concise conformation statistics theoretical approach based on Monte Carlo and Neural Network method. This method offers a new research idea for investigating the conformation statistics of complex polymers, characterized by its simplicity and practicality. It can be applied to more complex topological structure, more higher degree of freedom polymer systems with higher dimensions, theory research on dynamic self-consistent field theory and polymer field theory, as well as the analysis of scattering experimental data. The conformation statistics of complex polymers determine the structure and response properties of the system. Using the new method proposed in this study, taking the semiflexible ring diblock copolymer as an example, Monte Carlo simulation is used to sample this ring conformation to construct the dataset of polymer. The structure factor describing conformation statistics are expressed as continuous functions of structure parameters by neural network supervised learning. This is the innovation of this work. As an application, the structure factors represented by neural networks were introduced into the random phase approximation theory to study the microphase separation of semiflexible ring diblock copolymers. The influence of the ring's topological properties on the phase transition behavior was pointed out.

关键词： Ring copolymer Diblock copolymers Semiflexible The order-disorder transition

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