检索结果-南通市图书馆

Q full-waveform inversion based on the viscoacoustic equation

在线全文

学校读者我要写书评

暂无评论

Applied Geophysics 2019年第1期16卷 77-91页

作者： Wang En-jiang Liu Yang ji yu-xin Chen Tian-Sheng Liu Tao State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Beijing100083 School of Earth Science and Engineering Hohai UniversityNanjing210098 College of Geophysics and Information Engineering China University of Petroleum (Beijing)Beijing102249 Sinopec Petroleum Exploration and Production Research Institute Beijing100083 Sinopec Key Laboratory of Multiwave Seismic Technology Beijing100083

Presently, most full-waveform inversion methods are developed for elastic media and ignore the effect of attenuation. The calculation of the quality factor Q is based on velocity parameter inversion under the assumption of a given Q-model that is obtained by tomographic inversion. However, the resolution of the latter is low and cannot reflect the amplitude attenuation and phase distortion during wave propagation in viscoelastic media. Thus, a Q waveform inversion method is proposed. First, we use standard linear body theory to describe attenuation and then we derive the simplified viscoacoustic equation that characterizes amplitude attenuation and phase distortion. In comparison with conventional equations, the simplifi ed equation involves no memory variables and therefore requires less memory during computation. Moreover, the implementations of the attenuation compensation are easier. The adjoint equation and the corresponding gradient equation with respect to either L2-norm or the zero-lag cross-correlation objective function are then derived and the regularization strategy for overcoming the instability during numerical solution of the adjoint equation is proposed. The Q waveform inversion is developed using the limited-memory Broyden–Fletcher– Goldfarb–Shanno (L-BFGS) iteration method for known velocity. To alleviate the dependence of the waveform inversion on the initial model and overcome cycle skipping to some extent, we adopt multiscale analysis. Furthermore, anti-noise property and double-parameter inversion are assessed based on the results of numerical modeling.

关键词： Quality factor Q full-waveform inversion attenuation stability

细菌感染患者发生脓毒症的临床特点及危险因素分析

在线全文

学校读者我要写书评

暂无评论

广东医学 2024年第5期45卷 571-576页

作者：黄迪希欧阳慧罗玉婷纪宇欣刘曦中山大学附属第五医院感染病防治中心广东珠海519000 南华大学附属第二医院重症监护室湖南衡阳421200

目的分析细菌感染患者发生脓毒症的临床特点及危险因素。方法收集2019年10月1日至2020年9月30日细菌培养阳性患者2158例,其中脓毒症组229例,非脓毒症组1929例,收集患者一般资料、实验室检查结果、基础疾病史、临床表现等,比较两组患者... 详细信息

目的分析细菌感染患者发生脓毒症的临床特点及危险因素。方法收集2019年10月1日至2020年9月30日细菌培养阳性患者2158例,其中脓毒症组229例,非脓毒症组1929例,收集患者一般资料、实验室检查结果、基础疾病史、临床表现等,比较两组患者的临床特点并筛选出相关危险因素。采用非条件logistic回归模型分析筛选独立危险因素。结果两组相比,性别、年龄、吸烟、嗜酒、存在充血性心力衰竭、CKD、慢性乙型肝炎、肝硬化、恶性肿瘤差异具有统计学意义(P均<0.05)。男性(OR=2.17,P<0.01)、年龄(OR=1.01,P<0.05)、慢性乙型肝炎(OR=1.86,P<0.05)是脓毒症发生的独立危险因素。结论脓毒症与男性、高龄、吸烟、嗜酒显著相关;存在充血性心力衰竭、CKD、慢性乙型肝炎、肝硬化、恶性肿瘤等基础疾病的患者,更容易发生脓毒症。男性、高龄、慢性乙型肝炎是脓毒症发生的独立危险因素。

关键词：细菌感染脓毒症危险因素

Rotating magnetic field inhibits Aβ protein aggregation and alleviates cognitive impairment in Alzheimer’s disease mice

在线全文

学校读者我要写书评

暂无评论

Zoological Research 2024年第4期45卷 924-936页

作者： Ruo-Wen Guo Wen-jing Xie Biao yu Chao Song xin-Miao ji xin-yu Wang Mei Zhang xin Zhang High Magnetic Field Laboratory CAS Key Laboratory of High Magnetic Field and Ion Beam Physical BiologyHefei Institutes of Physical ScienceChinese Academy of SciencesHefeiAnhui 230031China Science Island Branch of Graduate School University of Science and Technology of ChinaHefeiAnhui 230036China Institutes of Physical Science and Information Technology Anhui UniversityHefeiAnhui 230601China School of Life Sciences Division of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui 230026China

Amyloid beta(Aβ)monomers aggregate to form fibrils and amyloid plaques,which are critical mechanisms in the pathogenesis of Alzheimer’s disease(AD).Given the important role of Aβ1-42 aggregation in plaque formation,leading to brain lesions and cognitive impairment,numerous studies have aimed to reduce Aβaggregation and slow AD *** diphenylalanine(FF)sequence is critical for amyloid aggregation,and magnetic fields can affect peptide alignment due to the diamagnetic anisotropy of aromatic *** this study,we examined the effects of a moderate-intensity rotating magnetic field(RMF)on Aβaggregation and AD *** indicated that the RMF directly inhibited Aβamyloid fibril formation and reduced Aβ-induced cytotoxicity in neural cells in *** the AD mouse model APP/PS1,RMF restored motor abilities to healthy control levels and significantly alleviated cognitive impairments,including exploration and spatial and non-spatial memory *** examinations demonstrated that RMF reduced amyloid plaque accumulation,attenuated microglial activation,and reduced oxidative stress in the APP/PS1 mouse *** findings suggest that RMF holds considerable potential as a non-invasive,high-penetration physical approach for AD treatment.

关键词： lzheimer’s disease Rotating magnetic field Amyloid-β Cognitive function Alzheimer’s disease animal models

Steam disinfection enhances bioaccessibility of metallic nanoparticles in nano-enabled silicone-rubber baby bottle teats,pacifiers,and teethers

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第2期136卷 161-171页

作者： yu Su BinWang xin Tong Shuchuan Peng Sijin Liu Baoshan xing Rong ji State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China School of Resources and Environmental Engineering Hefei University of TechnologyHefei 230009China State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Stockbridge School of Agriculture University of MassachusettsAmherstMA 01003USA

Nano-enabled silicone-rubber articles for feeding or chewing could be a source of metallic nanoparticles(NPs)directly exposed to infants and young ***,the impact of steam disinfection on release of NPs and the related potential risks to children's health are ***,we investigated contents and form of Ag and Zn in 57 nano-enabled silicone-rubber baby bottle teats,pacifiers,and teethers of seven countries and examined the impacts of steam disinfection on in vitro bioaccessibility(IVBA)of Ag and Zn in the *** 89%articles had a mixture of Ag-and Zn-containing NPs and the teethers had relatively high Ag and Zn contents(up to 501 and 254μg/g,respectively).Steam disinfection caused rubber decomposition into micro(nano)plastics(0.54-15.7μm)and NP release from the interior of bulk rubber and micro-sized plastics,thus enhancing the IVBA of Ag and Zn by up to 5.5 *** findings provide insights into mechanisms for NP release by steam *** oral exposure risk assessment suggested low health concerns on individual metal release,our study points out the need to assess the potential health risks of child co-exposure to metallic NPs and micro(nano)plastics.

关键词： Silicone rubber Metallic nanoparticles Micro(nano)plastics Bioaccessibility Children's health

Medication Rule Analysis of the Diagnosis and Treatment Programs of Chinese Medicine for the Prevention and Treatment of COVID-19 in China

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Integrative Medicine 2022年第9期28卷 779-784页

作者： ji xin-yu MA Yan SHI Shuai LIU Si-hong TONG Lin Lyu Cheng ZHANG Hua-min WANG Yan-ping Institute of Basic Research in Clinical Medicine China Academy of Chinese Medical SciencesBeijing100700China Guang’anmen Hospital China Academy of Chinese Medical SciencesBeijing100053China Institute of Information on Traditional Chinese Medicine China Academy of Chinese Medical SciencesBeijing100700China Institute of Chinese Materia Medica China Academy of Chinese Medical SciencesBeijing100700China

Objectives:To summarize the measures and rules of Chinese medicine(CM)and provide reference for clinical application in the prevention and treatment of coronavirus disease(COVID-19).Methods:The data source was from CM COVID-19 prevention and treatment programs on government websites and official media websites of the different provinces and *** search lasted from December 8,2019 to March 10,*** variables were medication frequency and combinations of *** analysis and complex network analysis were used by prevention and treatment stage and by ***:Among 27 CM diagnosis and treatment plans,203 therapeutic prescriptions were enrolled,of which the top 4 herbs were:Radix glycyrrhizae,Semen armeniacae amarum,Herba ephedrae,and Herba agastachis,*** core combinations were Herba ephedrae and Semen armeniacae ***-eight preventive formulae were *** herbs,including Radix Astragali seu hedysari,Radix glycyrrhizae,Radix saposhnikoviae,Flos lonicerae,*** most frequently *** core prescription of CM compatibility was Radix astragali seu hedysari,Radix glycyrrhizae,and Radix saposhnikoviae,which is the main component of yu Ping Feng *** were 45 prevention and treatment prescriptions in East China;the most used CM was Radix glycyrrhizae,Herba agastachis,Pericarpium citri reticulatae,and Gypsum *** prescriptions were identified in North *** to CM analyses,Herba agastachis,Semen armeniacae amarum,Herba ephedrae,and Poria were most frequently ***:CM for COVID-19 prevention mainly focuses on improving human immunity;for treatment,prescription focuses on clearing the lungs and removing *** vary with regions,perhaps due to climatic and environmental differences,which help clinicians to quickly make CM plans and treat patients according to clinical status,further minimizing resource wastage.

关键词： COVID-19 Chinese medicine regularity of medication

Accurate simulations of pure-viscoacoustic wave propagation in tilted transversely isotropic media

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第2期21卷 866-884页

作者： Qiang Mao jian-Ping Huang xin-Ru Mu ji-Dong Yang yu-jian Zhang Geosciences Department China University of Petroleum(East China)Qingdao266580ShandongChina Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao266207ShandongChina

Forward modeling of seismic wave propagation is crucial for the realization of reverse time migration(RTM) and full waveform inversion(FWI) in attenuating transversely isotropic media. To describe the attenuation and anisotropy properties of subsurface media, the pure-viscoacoustic anisotropic wave equations are established for wavefield simulations, because they can provide clear and stable wavefields. However, due to the use of several approximations in deriving the wave equation and the introduction of a fractional Laplacian approximation in solving the derived equation, the wavefields simulated by the previous pure-viscoacoustic tilted transversely isotropic(TTI) wave equations has low accuracy. To accurately simulate wavefields in media with velocity anisotropy and attenuation anisotropy, we first derive a new pure-viscoacoustic TTI wave equation from the exact complex-valued dispersion formula in viscoelastic vertical transversely isotropic(VTI) media. Then, we present the hybrid finite-difference and low-rank decomposition(HFDLRD) method to accurately solve our proposed pure-viscoacoustic TTI wave equation. Theoretical analysis and numerical examples suggest that our pure-viscoacoustic TTI wave equation has higher accuracy than previous pure-viscoacoustic TTI wave equations in describing q P-wave kinematic and attenuation characteristics. Additionally, the numerical experiment in a simple two-layer model shows that the HFDLRD technique outperforms the hybrid finite-difference and pseudo-spectral(HFDPS) method in terms of accuracy of wavefield modeling.

关键词： Pure-viscoacoustic TTI wave equation Attenuation anisotropy Seismic modeling Low-rank decomposition method

Enhanced thermoelectric and mechanical properties of Bi_(0.5)Sb_(1.5)Te_(3) alloy with dispersed yttrium oxide ceramic nanoparticles

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第4期43卷 1758-1768页

作者： Cun-Cheng Li Ming-Wei Zhang ji-Wu xin Lei Wei Wen-yu Zhao School of Materials Science and Engineering Shandong University of TechnologyZibo255000China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore639798Singapore State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China

Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based *** ceramic nanoparticles are good candidates for achieving this *** this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma *** to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were *** measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical ***,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal ***,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the *** addition,the Vickers hardness of the composite material was 35%higher than that of the *** study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.

关键词： Bi_(0.5)Sb_(1.5)Te_3 alloy Y_(2)O_(3) ceramic nanoparticles Microstructures Thermoelectric performance Mechanical properties

Rock physical characteristics of deep dolomite under complex geological conditions: A case study of 4th Member of Sinian Dengying Formation in the Sichuan Basin, China

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第4期21卷 2370-2382页

作者： Chuang Li Shu-xin Pan Hong-Bin Wang ji-xin Deng jian-Guo Zhao Zhi Li yu Zhang Northwest Branch of Research Institute of Petroleum Exploration & Development Department of Geophysics and Exploration College of Geophysics Chengdu University of Technology State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum (Beijing)

The deep-ultra deep carbonate reservoir in China, commonly subjected to modification of multi-stage diagenesis, has extremely high heterogeneity. Conventional rock physics analysis cannot accurately identify the elastic responses of reservoir. Here, the rock physics properties of the dolomite from the 4th Member of the Sinian Dengying Formation are experimentally measured, and the change law of rock physics characteristics is investigated within the framework of the diagenetic processes by the analysis of the elastic and petrologic characteristics, pore structure, and sedimentary environments. The results show that the differentiated diagenesis results in different pore structure characteristics and microtexture characteristics of the rock. The microbial dolomite of the algal mound-grain beach facies is subjected to the contemporaneous microbial dolomitization and seepage-reflux dolomitization, penecontemporaneous selective dissolution, burial dolomitization, and hydrothermal dolomitization. The resultant crystalline dolomite is found with one main type of the dolomite crystal contact boundaries,and the dissolution pore is extensive development. The siliceous, muddy, and limy dolomite of the interbeach sea environment mainly experiences the weak capillary concentration dolomitization, intensive mechanical compaction-induced densification, and burial dolomitization. Such crystalline dolomite is observed with four types of contact boundaries, namely the dolomite contact, clay contact, quartz contact, and calcite contact boundaries, and porosity mostly attributed to residual primary inter-granular or crystalline pores. The samples with the same crystal boundary condition have consistent correlations between the compressional-and shear-wave velocities, and between the compressional-wave velocity and the velocity ratio. Additionally, the variation of the acoustic velocity with effective pressure and the intensity of pore-scale fluid-related dispersion are controlled by t

关键词： Deep-ultra deep carbonate reservoirs Rock physics properties Dolomite Seismic elastic properties Micro-crack Pore structure types

Taiji-TianQin-LISA network:Precisely measuring the Hubble constant using both bright and dark sirens

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 59-77页

作者： Shang-jie jin Ye-Zhu Zhang ji-yu Song jing-Fei Zhang xin Zhang Key Laboratory of Cosmology and Astrophysics(Liaoning)&College of Sciences Northeastern UniversityShenyang 110819China Key Laboratory of Data Analytics and Optimization for Smart Industry(Ministry of Education) Northeastern UniversityShenyang 110819China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern UniversityShenyang 110819China

In the coming decades,the space-based gravitational-wave(GW)detectors such as Taiji,TianQin,and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole binaries(MBHBs).In this work,we investigate the potential of GW standard sirens from the Taiji-TianQin-LISA network in constraining cosmological *** the optimistic scenario in which electromagnetic(EM)counterparts can be detected,we predict the number of detectable bright sirens based on three different MBHB population models,i.e.,popⅢ,Q3d,and *** results show that the TaijiTianQin-LISA network alone could achieve a constraint precision of 0.9%for the Hubble constant,meeting the standard of precision ***,the Taiji-TianQin-LISA network could effectively break the cosmological parameter degeneracies generated by the CMB data,particularly in the dynamical dark energy *** combined with the CMB data,the joint CMB+Taiji-TianQin-LISA data offerσ(w)=0.036 in the wCDM model,which is close to the latest constraint result obtained from the CMB+SN *** also consider a conservative scenario in which EM counterparts are not *** to the precise sky localizations of MBHBs by the Taiji-TianQin-LISA network,the constraint precision of the Hubble constant is expected to reach 1.2%.In conclusion,the GW standard sirens from the Taiji-TianQin-LISA network will play a critical role in helping solve the Hubble tension and shedding light on the nature of dark energy.

关键词： space-based gravitational wave detection standard sirens the Taiji-TianQin-LISA network the Hubble constant dark energy