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Evolution hydrothermal aging resistance mechanism study of zirconium and manganese doped CeO_(2)catalysts in soot catalytic combustion based on low Miller indices crystal surface effect

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Journal of Rare Earths 2024年第7期42卷 1272-1281,I0003页

作者： Zonglin Li Pan Wang Hong Ni Chengcheng Ao Lidong Zhang Hefeng Zhang Kai Li School of Automotive and Traffic Engineering Jiangsu UniversityZhenjiang212013China State Environmental Protection Key Laboratory of vehicle emission control and Simulation Chinese Research Academy of Environmental ScienceBeijing100012China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei230026China

The thermogravimetric analysis(TGA)experiments were carried out to reveal the mechanism of Zr and Mn doping on catalytic activity of CeO_(2)catalyst both fresh and after hydrothermal aging,and the lattice morphology and valence changes were characterized by means of Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and H_(2)-temperature programmed reduction(H_(2)-TPR).Density functional theory(DFT)and molecular thermodynamics calculations were applied to investigate the change in catalytic activity,crystal surface energy and crystal morphology caused by hydrothermal *** maximum reaction rate temperature of fresh Mn/CeO_(2)(389℃)is similar to that of CeO_(2)(371℃)and lower than that of Zr/CeO_(2)(447℃),but the catalytic performance of CeO_(2)decreases more severely after hydrothermal *** catalyst crystals show different degrees of crystal surface migration after hydrothermal aging,which leads to the reduction of Ce^(3+)/Ce^(4+) ratio and the active sites *** calculations indicate that the doping of Zr and Mn reduces the surface energy of the low Miller indices surface and increases the oxygen vacancy formation energy,leading to better thermal stability and lower catalytic *** Zr and Mn doping also changes the adsorption energy and Gibbs free energy of H_(2)O,which dominates the migration of(111)to(110)and(100)in the vapor *** crystal surface migration mechanism of CeO_(2)catalysts doped with Zr and Mn induced by H_(2)O molecules at high temperature obtained in this study can provide a valuable addition to the regeneration of CeO_(2)catalysts in the after-treatment systems of diesel engines.

关键词： Soot CeO_(2)-based catalyst CDPF Rare earth metal oxides DFT calculations

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A FAS approach for stabilization of generalized chained forms: part 1. Discontinuous control laws

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Science China(Information Sciences) 2024年第2期67卷 118-143页

作者： Guang-Ren DUAN center for control Theory and Guidance Technology Harbin Institute of Technology center for control Science and Technology Southern University of Science and Technology

In this paper, a type of general nonholonomic systems is proposed, which contains both the Brockett’s two example systems, and their extended n-dimensional chained forms, as special cases. For the stabilization of such systems, a stabilizing controller is proposed based on the fully actuated system(FAS)approach, which is discontinuous at the origin but time-invariant when the open-loop system is time-invariant,and drives the feasible trajectories of the system to the origin exponentially. Furthermore, the proposed FAS approach is also extended to the sub-normal system case and the time-delay system case.

关键词： nonholonomic systems feedback stabilization exponential convergence sub-fully actuated systems time-delay systems

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Efficient NO_x abatement by passive adsorption over a Pd-SAPO-34 catalyst prepared by solid-state ion exchange

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Chinese Chemical Letters 2024年第4期35卷 210-213页

作者： Linhui Liu Wuwan Xiong Mingli Fu Junliang Wu Zhenguo Li Daiqi Ye Peirong Chen National Engineering Laboratory for VOCs Pollution control Technology and Equipment Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution ControlSchool of Environment and EnergySouth China University of TechnologyGuangzhou 510006China National Engineering Laboratory for Mobile Source emission control Technology China Automotive Technology&Research Center Co.Ltd.Tianjin 300300China

Palladium-exchanged chabazite(Pd-CHA) zeolites as passive NO_x adsorbers(PNAs) enable efficient purification of nitrogen oxides(NO_x) in cold-start diesel exhausts. Their commercial application, however,is limited by the lack of facile preparation method. Here, high-performance CHA-type Pd-SAPO-34 zeolite was synthesized by a modified solid-state ion exchange(SSIE) method using PdO as Pd precursor,and demonstrated superior PNA performance as compared to Pd-SAPO-34 prepared by conventional wetchemistry strategies. Structural characterization using Raman spectroscopy and X-ray diffraction revealed that the SSIE method avoided water-induced damage to the zeolite framework during Pd loading. Mechanistic investigations on the SSIE process by in situ infrared spectroscopy and X-ray photoelectron spectroscopy disclosed that, while PdO precursor was mainly converted to Pd^(2+) cations coordinated to the zeolite framework by consuming the-OH groups of the zeolite, a portion of PdO could also undergo thermal decomposition to form highly dispersed Pd~0 clusters in the pore channels. This simplified and scalable SSIE method paves a new way for the cost-effective synthesis of defect-free high-performance Pd-SAPO-34 zeolites as PNA catalysts.

关键词： Pd-SAPO-34 Passive NO_x adsorber Pd loading Solid-state ion exchange Pd transformation

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Temporal and Spatial Trends in HIV Positivity Rate for VCT Clinics—China,2015–2022

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China CDC weekly 2024年第1期6卷 6-11页

作者： Yi Liu Rong Su Dongmin Li Shaorong Wang Mengjie Han National center for AIDS/STD control and Prevention Chinese Center for Disease Control and PreventionBeijingChina

Introduction:Human immunodeficiency virus(HIV)voluntary counseling and testing(VCT)clinics play a critical role in identifying and diagnosing HIV *** study aimed to describe the trend of HIV positivity rate(HPR)among Chinese VCT clinics between 2015 and ***:This study utilized data from the China Information System for Disease control and Prevention to analyze the trend in the HPR for VCT clinics from 2015 to *** HPR was calculated by dividing the number of newly-reported HIV cases by the number of HIV tests,multiplied by 100%.To identify temporal and spatial trends in the HPR,we employed joinpoint regression analysis and the Getis-Ord hotspot ***:From 2015 to 2022,VCT clinics in China performed a total of 22,075,386 HIV tests,leading to the identification of 260,353 HIV cases,resulting in a HPR of 1.18%.The HPR consistently declined over the study period,with an average annual percent change(AAPC)of−7.5%(95%confidence interval:−12.6%,−2.2%,P<0.05).The number of HPR hotspots also decreased from 41 in 2015 to 23 in *** HPR hotspots were primarily located in Yunnan,Sichuan,Guangdong,and Guangxi provincial-level administrative divisions(PLADs).Among the 31 PLADs,16 showed a significant decrease in HPR during the study period(AAPC<0,PAAPC<0.05).Conclusions:VCT clinics in China have played a significant role in identifying HIV *** declining HPR observed in these clinics may indicates the progress has been made in some degree in mitigating HIV among high-risk ***,it is crucial to further improving the utilization of VCT clinics for HIV testing.

关键词： VCT dividing Spatial

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Characteristics of the HIV/AIDS Epidemic among People Aged≥50 Years in China during 2018–2021

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Biomedical and Environmental Sciences 2024年第4期37卷 399-405页

作者： HOU Yu Shan JIN Yi Chen CAI Chang TANG Hou Lin QIN Qian Qian LYU Fan National center for AIDS/STD control and Prevention Chinese Center for Disease Control and PreventionBeijing 102206China

Objective This study aimed to determine the current epidemiological status of PLWHA aged≥50 years in China from 2018 to *** also aimed to recommend targeted interventions for the prevention and treatment of HIV/AIDS in elderly *** Data on newly reported cases of PLWHA,aged≥50 years in China from 2018 to 2021,were collected using the *** tests and spatial analyses were also *** Between 2018 and 2021,237,724 HIV/AIDS cases were reported among patients aged≥50 years in *** main transmission route was heterosexual transmission(91.24%).Commercial heterosexual transmission(CHC)was the primary mode of transmission among males,while non-marital non-CHC([NMNCHC];60.59%)was the prevalent route in *** proportion of patients with CHC decreased over time(Z=67.716,P<0.01),while that of patients with NMNCHC increased(Z=153.05,P<0.01).The sex ratio varied among the different modes of infection,and it peaked at 17.65 for *** spatial analysis indicated spatial clustering,and the high-high clustering areas were mainly distributed in the southwestern and central-southern *** In China,PLWHA,aged≥50 years,were predominantly infected through heterosexual *** primary modes of infection were CHC and *** were variations in the sex ratio among different age groups,infected through various sexual ***/AIDS cases exhibited spatial *** on these results,the expansion of HIV testing,treatment,and integrated behavioral interventions in high-risk populations is recommended to enhance disease detection in key regions.

关键词： HIV/AIDS Aged≥50 years China

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Prevalence and serotype distribution of nasopharyngeal carriage of Streptococcus pneumoniae among healthy children under 5 years of age in Hainan Province, China

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Infectious Diseases of Poverty 2024年第1期13卷 42-52页

作者： Jian Wang Li Qiu Shuang Bai Wei Zhao Ao Zhang Jing Li Jun-Nan Zhang Shan-Shan Zhou Ren Qiu Zhu Huang Jv-Xia Liu Ting-Bin Wang Xue Sun Jiang Wu Qun Zheng Bin He Min Lv Beijing center for Disease Prevention and control BeijingChina Beijing Research center for Respiratory Infectious Diseases BeijingChina Hainan Provincial center for Disease control and Prevention HaikouChina Haikou center for Disease control and Prevention HaikouHainanChina Wanning center for Disease control and Prevention WanningHainanChina Baisha County center for Disease control and Prevention BaishaHainanChina Qiongzhong County center for Disease control and Prevention QiongzhongHainanChina

Background The thirteen-valent pneumococcal conjugate vaccine(PCV13)is not included in the national immu-nization program and is administered voluntarily with informed consent in *** preparation for assessing the impact of pilot introduction in Hainan Province,we conducted a carriage study among children under 5 years of age from four locations in Hainan Province,*** From March to June 2022,nasopharyngeal(NP)swabs,collected from healthy children aged younger than 59 months who lived in the 4 different locations(Haikou,Wanning,Baisha and Qiongzhong)in Hainan Province,were tested for pneumococcus using conventional *** isolates were serotyped using the Quel-lung *** factors associated with pneumococcal colonization were assessed using univariate analysis and multivariable logistic regression adjusting for age,daycare attendance and other *** Pneumococcus was isolated in 710(30.4%)of the 2333 children *** 737 pneumococci,29 serotypes were identifed;60.9%were PCV13 serotypes;the most common vaccine serotypes were 6B(20.4%),19F(13.0%),6A(11.9%)and 23F(6.1%);and the most common nonvaccine serotypes were 23A(12.9%),34(6.1%)and nontypeable(NT)pneumococci(5.6%).Children vaccinated with PCV13 had lower carriage(17.7%vs 32.5%;P=0.0001)and fewer PCV13 serotypes(41.9%vs 62.7%;P=0.0017)compared to unimmunized *** adjustment,NP carriage Was higher among children attending daycare(aOR=2.3,95%CI:1.7-3.2),living in rural areas(aOR=1.4,95%CI:1.1-1.8),living with siblings(aOR=1.3,95%CI:1.0-1.6)and whose mothers had completed senior high/technical sec-ondary school(aOR=1.5,95%CI:1.1-2.0).In contrast,completion of 3-4 doses of PCV13 were associated with a lower carriage rate(aOR=0.6,95%CI:0.4-0.9).Conclusions We established the baseline of pneumococcal carriage,serotype distribution and PCV13 immuni-zation rates among healthy children under 5 years of age in Hainan Province,prior to the introduction of PCV13 into th

关键词： Pneumococcus Nasopharyngeal carriage Serotypes distribution Children Hainan Province China

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Numerical analysis of wind effects on aerodynamic characteristics of a ducted fan

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Chinese Journal of Aeronautics 2024年第5期37卷 263-280页

作者： Yiwei LUO Tianfu AI Yuhang HE Bin XU Yuping QIAN Yangjun ZHANG State Key Laboratory of Intelligent Green vehicle and Mobility School of Vehicle and MobilityTsinghua UniversityBeijing 100084China Key Laboratory of Conveyance and Equipment Ministry of Education East China Jiaotong UniversityNanchang 330013China vehicle Research center School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation center Chongqing 401120China

Ducted fans have been extensively used in Unmanned Aerial vehicles(UAVs)for a variety of missions because of high efficiency,high safety and low ***,as a kind of typical meteorological condition,brings significant aerodynamic interference to the ducted fan,which seriously threatens flight stability and *** this work,the numerical simulation with the Unsteady Reynolds Averaged Navier-Stokes(URANS)method and the sliding mesh technique is performed to evaluate the steady wind *** results show that the wind will lead to serious unsteady effects in the flow field,and the thrust fluctuates at the blade passing frequency of 200 *** the wind speed increases,the rotor thrust increases,the duct thrust decreases,and the total thrust changes *** instability may occur when the wind speed exceeds 8 m/*** the angle of low-speed wind increases,the rotor thrust changes little,the duct thrust increases,and the total thrust *** addition,we figure out that cases with the same crosswind ratio are similar in results,and increasing the rotating speed or fan radius is beneficial to performance improvement in *** findings are essential to the ducted fan design and UAV flight control design for stable and safe operations in wind conditions.

关键词： Unmanned Aerial vehicle(UAV) Ducted fan Wind effect Thrust fluctuations Computational Fluid Dynamics(CFD)

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Effect of CeO_(2) nanoparticle sizes on catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst in NH_(3)-SCR reaction

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Journal of Rare Earths 2024年第3期42卷 515-522,I0004页

作者： Zhenghua Hu Dongqi An Lei Zhang Xuping Wang Siyong Fang Xinyun Tian Liu Qiu Jingfang Sun Tingzhen Li Lin Dong School of Environmental and Chemical Engineering Chongqing Three Gorges UniversityChongqing404000China Key Laboratory of Water Environment Evolution and Pollution control in the Three Gorges Reservoir Chongqing Three Gorges UniversityChongqing404000China Jiangsu Key Laboratory of vehicle emissions control Center of Modern AnalysisNanjing UniversityNanjing210093China

The sulfated CeO_(2)/Al_(2)O_(3) catalysts with different sizes of CeO_(2)nanoparticles were prepared by using pure H_2O or acetic acid solution as impregnation solvent, and the influence of sizes of CeO_(2) nanoparticles on the catalytic performances of the sulfated CeO_(2)/Al_(2)O_(3) catalyst was studied. The catalytic performance tests show that the sulfated CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution as impregnation solvent has better catalytic activity and the resistance to K+poisoning than the sulfated CeO_(2)/Al_(2)O_(3) catalyst using pure H_(2)O as impregnation solvent. The excellent catalytic performances can be ascribed to the smaller sizes of CeO_(2) nanoparticles in CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution, which results in larger amount of adsorbed sulfate species, surface acid sites, surface active oxygen species and excellent redox property. These features are helpful for improving the catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst using smaller amount of CeO_(2) to cut the costs.

关键词： Cerium-based catalyst Nanoscale effect NH_(3)selective catalytic reaction Sulfation process Alkali metal poisoning Rare earths

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Tracked robot with underactuated tension-driven RRP transformable mechanism:ideas and design

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Frontiers of Mechanical Engineering 2024年第1期19卷 85-104页

作者： Ran XU Chao LIU School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Key Laboratory of vehicle Advanced Manufacturing Measuring and Control Technology(Ministry of Education)Beijing Jiaotong UniversityBeijing 100044China

Robots with transformable tracked mechanisms are widely used in complex terrains because of their high adaptability,and many studies on novel locomotion mechanisms have been conducted to make them able to climb higher *** underactuated transformable mechanisms for tracked robots could decrease the number of actuators used while maintaining the flexibility and obstacle-crossing capability of these robots,and increasing their cost ***,the underactuated tracked robots have appreciable research *** this paper,a novel tracked robot with a newly proposed underactuated revolute‒revolute‒prismatic(RRP)transformable mechanism,which is inspired by the sit-up actions of humans,was *** newly proposed tracked robot has only two actuators installed on the track pulleys for moving and does not need extra actuators for ***,it could concentrate the track belt’s tension toward one side,and the unbalanced tension would drive the linkage mechanisms to change its *** this method,the proposed underactuated design could change its external shape to create support points with the terrain and move its center of mass actively at the same time while climbing obstacles or crossing other kinds of terrains,thus greatly improving the climbing capability of the *** geometry and kinematic relationships of the robot and the crossing strategies for three kinds of typical obstacles are *** the basis of such crossing motions,the parameters of links in the robot are designed to make sure the robot has sufficient stability while climbing ***-crossing dynamic simulations were run and analyzed to prove the feasibility of the robot.A prototype was built and *** show that the proposed robot could climb platforms with heights up to 33.3%of the robot’s length or cross gaps with widths up to 43.5%of the robot’s length.

关键词： mechanical design tracked robot underactuated mechanisms RRP mechanism obstacle crossing strategy

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Epidemiological characteristics of centenarian deaths in China during 2013-2020:A trend and subnational analysis

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Chinese Medical Journal 2024年第13期137卷 1544-1552页

作者： Fan Mao Weiwei Zhang Peng Yin Lijun Wang Jinling You Jiangmei Liu Yunning Liu Maigeng Zhou National center for Chronic and Non-Communicable Disease control and Prevention Chinese Center for Disease Control and PreventionBeijing 100050China

Background:Studies that comprehensively address the characteristics of centenarian deaths are *** present study aimed to depict the characteristics of centenarian deaths in China and their changing ***:Data on centenarian deaths between 2013 and 2020 were obtained from the national mortality surveillance system of China,including date,place of death(PoD),and underlying cause of death(CoD).Descriptive analyses were performed to understand the epidemiological characteristics,and a joinpoint regression model was adopted to examine the changing trends in the proportions of different PoDs,CoDs among centenarians,and centenarian deaths accounting for all deaths and deaths among people aged 65 years and ***:There were 46,938 registered centenarian deaths between 2013 and 2020 that included 34,311 females(73.10%)and 12,627 males(26.90%).January(12.05%),February(9.99%),and December(9.74%)were the top three months with the highest number of *** proportions of deaths that occurred in homes,hospitals,and nursing homes were 81.71%,13.63%,and 2.68%,*** proportion of deaths in nursing homes increased by 9.60%(95%confidence intervals[CIs],6.4-12.9%)from 2014 to *** disease(35.72%)was the leading cause of death,followed by respiratory diseases(17.63%),cerebrovascular disease(15.60%),and old age(11.22%).The proportion of respiratory diseases decreased by 4.8%(95%CI,-8.8 to-0.7%),and the proportion of deaths from old age decreased by 2.3%(95%CI,-4.4 to-0.1%)per *** had the highest proportions of deaths in hospitals(39.38%)and nursing homes(14.68%).Sichuan had the highest proportion of deaths attributed to respiratory diseases(32.30%),while Jiangsu(26.58%)and Zhejiang(23.61%)had the highest proportions of deaths from old ***:Unlike other countries,centenarian deaths in China are characterized by a higher proportion of home and heart disease deaths,and this death pattern differs across provinces.

关键词： Centenarians Death Aging Cardiovascular diseases Respiratory tract diseases Place of death Cause of death

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