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Magnitude and direction of temperature variability affect hospitalization for myocardial infarction and stroke:population-based evidence from Guangzhou,China

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Frontiers of Environmental Science & Engineering 2024年第3期18卷 1-11页

作者： Zhou Yang Murui Zheng Ze-Lin Yan Hui Liu Xiangyi Liu Jie-Qi Jin jiagang wu Chun-Quan Ou State Key Laboratory of Organ Failure Research Department of BiostatisticsGuangdong Provincial Key Laboratory of Tropical Disease ResearchSchool of Public HealthSouthern Medical UniversityGuangzhou 510515China Guangzhou Center for Disease Control and Prevention Guangzhou 510440China

Relationships between nonoptimal temperatures and cardiovascular disease(CVD)mortality have been well ***,evidence of the association between temperature variability(TV)and CVD morbidity is *** study aimed to quantify the risk and burden of CVD-related hospitalization associated with the magnitude and direction of *** on meteorology and population-based hospitalizations for myocardial infarction(MI)and stroke were collected in Guangzhou,China,from 2013 to *** temperature variability(HTV)was measured as the standard deviation of hourly temperature records over specific exposure *** direction(upward or downward)of HTV was defined as the average daily mean temperature change relative to that of the previous day during the exposure ***-Poisson regression was applied to assess the impact of HTV after adjusting for the daily mean temperature,and the hospitalization fractions attributable to HTV were calculated.A 1℃-increase in HTV was significantly associated with a 2.24%and 1.72%increase in hospitalizations for MI and hemorrhagic stroke(HS)at lag 0–1 d,respectively,and a 1.55%increase in hospitalizations for ischemic stroke(IS)at lag 0–3 *** the study period,5.99%,4.64%,and 4.53%of MI,HS,and IS hospitalizations,respectively,were attributable to *** upward TV exerts acute effects on CVD hospital admissions,whereas the impact of downward TV generally *** findings highlight the importance of the magnitude and direction of temperature fluctuations,in addition to the mean level,in assessing the adverse health impacts of temperature variations.

关键词： Hourly temperature variability Cardiovascular Hospitalization Direction China

Enhanced strain and electrostrictive properties in lead-free BNT-based ceramics via rare earth doping

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Journal of Materiomics 2022年第2期8卷 401-407页

作者： Anping Deng jiagang wu Department of Materials Science Sichuan UniversityChengdu610064China

Bi_(0.5)Na_(0.5)TiO_(3)(BNT)-based ceramics are one of the most promising lead-free ferroelectrics due to their high strain *** to other chemical modifications,rare earth ions doping provides sig-nificant possibility to optimize the strain property of BNT-based *** this work,the effects of rare earth ions on phase structure,microstructure,and strain&electrostrictive properties of lead-free BNT-based ceramics were systematically *** earth ions(i.e.,La^(3+),Sm^(3+),Yb^(3+),Dy^(3+),and Nd ^(3+))were selected as the doping *** moderate La^(3+)ions can drive the ferroelectric state of BNT-based ceramics to nonergodic relaxor state or ergodic relaxor *** enhanced strain response of~0.40-0.42% and high converse piezoelectric coefficient of~600-630 pm/V can be achieved under 60-70 kV/cm for La^(3+)-doped ceramic with nonergodic relaxor ***,the giant electrostrictive coefficient Q 33 of~0.047 m 4/C 2 can be obtained for La ^(3+)-doped ceramic with ergodic relaxor *** rare earth ions also present the promotion effect on strain enhancement for BNT-based *** study affords a significant guidance to optimize strain and electrostrictive properties of BNT-based ce-ramics via rare earth ions doping.

关键词： BNT-based ceramics Rare earth doping Strain property Electrostrictive property Structure transition

Insight into the large electro-strain in bismuth sodium titanate-based relaxor ferroelectrics:From fundamentals to regulation methods

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Journal of Materials Science & Technology 2023年第19期150卷 27-48页

作者： Xiaojun wu Lanji Wen Chao wu Xiang Lv Jie Yin jiagang wu College of Materials Science and Engineering Sichuan University610064PR China

Due to the demand for environmental protection,developing eco-friendly piezoelectric applica-tions/materials is an inevitable *** market share of lead-free materials is growing steadily every *** typical lead-free systems,Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has attracted wide attention due to its supe-rior strain property(e.g.,dynamic piezoelectric coefficient d33*of most modified-BNT ceramics exceeds 600 pm/V,which is higher than commercial soft PZT ceramics PIC151).The excellent strain performance in BNT-based materials is thought to arise from the relaxor-ferroelectric transition,and currently,the mainstream strain regulation method is chemical *** far,amounts of effective dopants have been investigated,while the intrinsic strain regulation mechanism is still ambiguous(e.g.,how do dopants work?).Therefore,we review the intrinsic strain regulation mechanism,and strain origination and reg-ulation methods are also investigated to comprehend the regulation ***,the strain origination and regulation mechanism are investigated from different dimensions(e.g.,macro perspective and micro perspective),which is vacant in previous *** the macro view,the particular tai-lored relaxor-ferroelectric crossover is the critical key for the giant electro-strain,while from the micro view,the electro-strain is dominated by the cracked ferroelectric order and relaxor-ferroelectric transi-tion,resulting from the broken Bi-O bonds due to the local field *** the strain origination and regulation mechanism of BNT-based ceramics is of great importance to exclude the blind researching mode and rationally design the experimental scheme.

关键词： Strain origin Bi_(0.5)Na_(0.5)TiO_(3)(BNT) Strain regulation

Tailoring depolarization temperature by phase transition causing properties evolution in Bi_(0.5)(Na_(1-x)K_(x))_(0.5)TiO_(3)ceramics

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Journal of Materials Science & Technology 2022年第19期114卷 111-119页

作者： Diyan Yang Jihui Han Jie Yin Haoyue Xue jiagang wu Department of Materials Science Sichuan UniversityChengdu610065China

(Bi_(0.5)Na_(0.5))TiO_(3)-based materials have attracted widespread attention due to large electro-strain,large remnant polarization(P r)and high Curie temperature(T C),but the existence of inherent depolarization temperature(T d)limits the temperature stability and application temperature *** this work,we find that K/Na ratio can regulate T d(from 90℃to 246℃)of the ceramics,which confirms that the increase of K substitution can effectively improve the temperature stability of the *** phase structure and electrical properties of Bi_(0.5)(Na_(1-x)K_(x))_(0.5)TiO_(3)(BNKT x)ceramics can be well modulated by changing K/*** addition,BNKT x system exhibits excellent piezoelectric response at morphotropic phase boundary(MPB)of 20%BKT content(d_(33)=180 pC/N),where rhombohedral(R 3 c)phase and tetragonal(P 4 bm)phase coexist in *** K further substitution,BNKT x ceramics transform into tetragonal phase,and the domain size grows due to the structural transition from short-range-correlated P 4 bm to long-range-correlated P 4 *** deferment of T d is also tightly related to the increase of P 4 mm/P 4 bm *** work can provide an effective way to tailor depolarization temperature and electrical properties of BNT-based ceramics.

关键词： Depolarization temperature (Bi_(0.5)Na_(0.5))Ti_(O 3) Piezoelectric ceramics Piezoelectric constant Temperature stability

Coupling effects of the A-site ions on high-performance potassium sodium niobate ceramics

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Journal of Materials Science & Technology 2022年第35期130卷 198-207页

作者： Xiang Lv Nan Zhang Yinchang Ma Xi-xiang Zhang jiagang wu Department of Materials Science Sichuan UniversityChengdu 610065China Division of Physical Science and Engineering King Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia

Although vast efforts have been given to the phase boundary engineering(PBE) of potassium sodium niobate(KNN) ceramics by using chemical dopants,the inherent issues like the K/Na ratio were not paid enough attention,hindering the further understanding of physical ***,we investigated the effect of the K/Na ratio on PBE-featured KNN-based *** K/Na ratio significantly influences the local A-site environment and thereby alters mesoscopic ferroelectric domains and macroscopic structure and performance.A much higher Na^(+)content results in the local stress heterogeneity,while a much higher K^(+)content brings in the local polar *** to the appropriate coupling between the local stress and the polar heterogeneity,piezoelectric properties and the temperature stability of electrostrain are optimized on the Na-rich ***,beyond seeking appropriate chemical dopants,elaborately tailoring the K/Na ratio is also important for further improving the piezoelectric properties of PBE-featured KNN-based ceramics.

关键词： KNN ceramics K/Na ratio Piezoelectricity Local heterogeneity Physical mechanisms

Low-temperature dielectric relaxation associated with NbO_6 octahedron distortion in antimony modified potassium sodium niobate ceramics

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Journal of Materials Science & Technology 2022年第20期115卷 189-198页

作者： Nan Zhang Xiang Lv Xi-xiang Zhang Jing Lyu Shuo-Wang Yang jiagang wu Department of Materials Science Sichuan UniversityChengdu 610065China Division of Physical Science and Engineering King Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia Department of Chemistry National University of Singapore3 Science Drive 3117543Singapore Institute of High Performance Computing Agency for ScienceTechnology and Research1 Fusionopolis Way#16-16 Connexis138632Singapore

Although the antimony(Sb) has been widely used to modify potassium sodium niobate(KNN) ceramics for tailoring the phase structure and performance, the role of Sb still remains insufficiently understood,consequently hindering the understanding of the physical origin of high-performance KNN-based ceramics. Here, we combine the experiments and first-principles calculations to deeply reveal the effects of Sb on KNN ceramics. Our results reveal a re-entrant-like relaxation behavior near the rhombohedralorthorhombic(R-O) phase transition at the low content of Sb, which transforms into a canonical one at higher content of Sb. First-principles calculations show a significantly decreased difference in the bond length of six B-O bonds of Nb O6 octahedral in Sb-modified KNN ceramics compared to pristine KNN ceramics, responsible for the low-temperature re-entrant-like dielectric relaxation. Furthermore, the addition of Sb would soften the B-O repulsion and gradually break the long-range ferroelectric ordering,resulting in the occurrence of nanoscale domains and enhanced local heterogeneity. Finally, we find that the optimized piezoelectric properties are the trade-off between the long-range ferroelectric ordering and the local heterogeneity. Therefore, this work not only deeply reveals the effects of Sb on KNN ceramics from multi-scale perspectives but also helps the future composition design for achieving high piezoelectricity.

关键词： KNN-based ceramics Re-entrant-like relaxation Covalency Multiphase coexistence Local heterogeneity

Synergy of lead vacancies and morphotropic phase boundary to promote high piezoelectricity and temperature stability of PBZTN ceramics

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Journal of Materials Science & Technology 2023年第6期137卷 1-7页

作者： Wenbin Liu Ting Zheng Xuezheng Ruan Zhenyong Man Haoyue Xue Laiming Jiang Fuping Zhang Guorong Li jiagang wu Department of Materials Science Sichuan UniversityChengdu 610065China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 201800China Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621900China

The flourishing development of emerging electromechanical applications has stimulated an urgent demand for ferroelectric ceramics with high piezoelectric properties and broad temperature usage ***,it remains a challenge to simultaneously obtain good piezoelectricity and reliable temperature stability in lead zirconate titanate(PZT)-based piezoelectric *** solve this issue,a synergetic strategy was proposed to introduce lead vacancies through niobium doping and construct morphotropic phase boundary(MPB).In this work,Pb_(0.905)Ba_(0.085)(V Pb″)_(0.01)[(Zr_(x)Ti_(1-x))_(0.98)Nb_(0.02)]O_(3)(PBZTN-x)material system was *** comprehensive properties(d_(33)=864 pC/N,k_(p)=84%,T_(C)=201℃)and excellent temperature stability(less than 10%variation of electrical properties from 20℃ to 160℃)were obtained in PBZTN-0.540 *** piezoelectricity can be attributed to high extrinsic contribution(domain wall motion)induced by Pb^(2+)vacancies and the existence of nano-domains emerged at MPB,while excellent temperature stability is mainly attributed to the minimized local stress in the lattice and the stable domain structure.

关键词： Piezoelectricity Lead vacancies Morphotropic phase boundary Temperature stability

Magnetoelectric coupling at microwave frequencies observed in bismuth ferrite-based multiferroics at room temperature

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Journal of Materials Science & Technology 2023年第6期137卷 100-103页

作者： Man Zhang Vladimir Koval Yu Shi Yajun Yue Chenglong Jia jiagang wu Giuseppe Viola Haixue Yan School of Engineering and Materials Science Queen Mary University of LondonMile End RoadLondon E14NSUK Institute of Materials Research Slovak Academy of SciencesWatsonova 47Kosice 04001Slovakia Key Laboratory for Magnetism and Magnetic Materials of MOE Lanzhou UniversityLanzhou 730000China Department of Chemistry Queen Mary University of LondonMile End RoadLondon E14NSUK Department of Materials Science Sichuan UniversityChengdu 610064China

***,In the search for advanced multifunctional materials for next generation sensors and logic devices,magnetoelectric multifer-roics exhibiting simultaneously ferromagnetism and ferroelectric-ity within the same phas... 详细信息

关键词： microwave coupling ferroelectric

Multiscale Structure Engineering for High-Performance Pb-Free Piezoceramics

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Accounts of Materials Research 2022年第4期3卷 461-471页

作者： Xiang Lv Ting Zheng Chunlin Zhao Jie Yin Haijun wu jiagang wu Department of Materials Science Sichuan UniversityChengdu 610064China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

CONSPECTUS:The increasing world energy crisis drives humans to harvest the energy in nature as much as possible without heavily damaging the ***,most of the energy in nature cannot be used ***,pursuing technologies or matter that can directly interconvert different energies has been one of the most cutting-edge fields in science and *** a magic ability exists in true-life piezoelectric materials that generate charge when being given a force and vice versa,rendering them highly promising for energy harvesting and conversion because of the tremendous mechanical energy on the earth,such as tide ***,piezoelectric materials,represented by the lead zirconate titanate(Pb(Zr,Ti)O_(3),PZT)family,have been largely used in various traditional and burgeoning fields,such as electronic information,biomedical treatment,and wearable flexible electronic devices,and are one of the most important favorites in multidisciplinary ***,Pb is highly *** by environmental protection and concern for human health,Pb-free piezoceramics are rapidly being developed to hopefully replace Pb-based *** particular,the renewal of Restriction of the use of certain Hazardous Substances(e.g.,RoHS 2),issued by the European Union,declared that replacement of PZT“...may be scientif ically and technologically practical to a certain degree...”.Therefore,developing high-performance Pb-free piezoceramics has become more urgent than *** this context,some Pb-free piezoceramics,represented by potassium sodium niobate((K,Na)NbO_(3),KNN),barium titanate(BaTiO_(3),BT),bismuth barium titanate((Bi,Na)TiO_(3),BNT),and bismuth ferrite(BiFeO_(3),BFO),stand out because of their unique or similar ***,several key challenges,including an inferior overall performance compared to Pb-based counterparts and an unclear structure−property relationship from multiscale viewpoints,have severely hindered the development of Pb-free piezoceramics for

关键词： ceramics piezoelectric bismuth