检索结果-南通市图书馆

Weyl Type Theorem for Bounded Linear Operator and Its Functional Calculus

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第2期40卷 528-536页

作者： Gao hui zi FENG Peng Tong LI School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

Let H be a complex infinite dimensional Hilbert space and B(H)be the algebra of all bounded linear operators on *** this paper,we mainly study the operators that satisfy both a-Weyl's theorem and property(R).Also,the operators whose functional calculus satisfies the two properties are also *** give the features for the operator or its functional calculus for which both a-Weyl's theorem and property(R)hold.

关键词： a-Weyl's theorem property(R) functional calculus

The fast method and convergence analysis of the fractional magnetohydrodynamic coupled flow and heat transfer model for the generalized second-grade fluid

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2024年第4期67卷 919-950页

作者： Xiaoqing chi hui Zhang Xiaoyun Jiang School of Mathematics and Statistics Shandong UniversityWeihai 264209China School of Mathematics Shandong UniversityJinan 250100China

In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade *** coupled model consists of a fractional momentum equation and a heat conduction equation with a generalized form of Fourier *** second-order fractional backward difference formula is applied to the temporal discretization and the Legendre spectral method is used for the spatial *** fully discrete scheme is proved to be stable and convergent with an accuracy of O(τ^(2)+N-r),whereτis the time step-size and N is the polynomial *** reduce the memory requirements and computational cost,a fast method is developed,which is based on a globally uniform approximation of the trapezoidal rule for integrals on the real *** strict convergence of the numerical scheme with this fast method is *** present the results of several numerical experiments to verify the effectiveness of the proposed ***,we simulate the unsteady fractional MHD flow and heat transfer of the generalized second-grade fluid through a porous *** effects of the relevant parameters on the velocity and temperature are presented and analyzed in detail.

关键词： fractional MHD coupled flow and heat transfer model generalized second-grade fuid fast method convergence analysis numerical simulation

Chain Dynamics Heterogeneity in Plasticized Poly(vinyl butyral)(PVB) as Elucidated by Solid-State NMR

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2024年第1期42卷 113-124,I0010页

作者： Jing Lv Xu Chen zi-Shuo Wu Ya-hui Li Wei Chen National Synchrotron Radiation Laboratory Anhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmCAS Key Laboratory of Soft Matter ChemistryUniversity of Scienceand Technology of ChinaHefei 230026China

The chain dynamics heterogeneity of the poly(vinyl butyral)(PVB) plasticized by triethylene glycol bis(2-ethylhexa noate)(TEG-EH) was investigated by various solid-state NMR *** plasticized PVB shows two domains in distinct molecular dynamics differences,namely,rigid and soft domains,where the latter is the plasticizer-rich *** time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB,and the results show the decreasing activated energy of components in the soft domain of plasticized PVB(E_a=20.2 kJ/mol) as compared with that of the pristine one(E_a=24.3 kJ/mol).Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific *** quadrupole-echo ~2H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol(VA) units,where only the hydroxyl group of VA is *** ~1H-^(13)C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer,whereas the glass transition temperature differed by approximately 53℃.This is further supported by Torchia's T_1 relaxation *** origin of such an unusual phenomenon is attributed to the critical role of the remaining VA(~22%) in the soft domain,where the VA units locally aggregate through hydrogen ***,the existence of a mobility gradient in the VB unit has been ***,the mobility difference for VB with different stereo-geometry(meso or racemic conformation) is observed for the first *** indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic perfo rmance of PVB.

关键词： Poly(vinyl butyral) Dynamics heterogeneity Plasticizer Solid state NMR

Significant annealing-induced hardening effect in nanolaminate d-nanotwinne d(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)me dium-entropy alloy by severe cold rolling

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第3期170卷 156-166页

作者： Shuqing Yuan hui Fu Lei Qian chi Fai Cheung Xu-Sheng Yang State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518060China

Due to the easy coarsening caused by poor thermal stability,the verified annealing-induced hardening in nanograined metals can only maintain at a relatively low-temperature *** this study,a nanolam-inated(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)medium-entropy alloy with an average lamellae thickness of∼20 nm embedded by thinner nanotwins was fabricated by severe cold rolling to achieve superior thermal *** with the conventional nanotwinned CrCoNi with nanotwins inside ultra-fined grains,the hier-archical nanolaminated-nanotwinned(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8) exhibits a significant annealing-induced hard-ening effect,i.e.,hardness increasing from∼250 HV in the original specimen to∼500 HV in the cold-rolled status and finally∼630 HV after annealing at 600℃for 1 *** microstructure characterizations reveal that the reduced dislocation density and formation of L1_(2)ordered domain are mainly responsible for such hardening effect,which is facilitated by the effectively suppressed coarsening with annealing temperature,i.e.,slow detwinning process and well-retained low-angle nanolamellar *** coarsening mechanisms from the cold-rolled nanolamellae to the fully recrystallized micro-equiaxed structures under the annealing temperatures ranging from 400 to 800℃ were also elucidated by atomic observations.

关键词： Annealing-induced hardening Thermal stability Nanolaminated-nanotwinned structure CrCoNi Detwinning Grain boundary migration

SIRT1 inhibits apoptosis of human lens epithelial cells through suppressing endoplasmic reticulum stress in vitro and in vivo

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2024年第7期17卷 1205-1216页

作者： hui Cui Di Sun Sheng Meng Tian-Ju Ma zi Ye Zhao-hui Li Medical School of chinese PLA Beijing 100089China Senior Department of Ophthalmology the Third Medical Center of PLA General HospitalBeijing 100853China

AIM:To explore the effect of silent information regulator factor 2-related enzyme 1(SIRT1)on modulating apoptosis of human lens epithelial cells(HLECs)and alleviating lens opacification of rats through suppressing endoplasmic reticulum(ER)***:HLECs(SRA01/04)were treated with varying concentrations of tunicamycin(TM)for 24h,and the expression of SIRT1 and C/EBP homologous protein(CHOP)was assessed using real-time quantitative polymerase chain reaction(RT-PCR),Western blotting,and *** morphology and proliferation was evaluated using an inverted microscope and cell counting kit-8(CCK-8)assay,*** the SRA01/04 cell apoptosis model,which underwent siRNA transfection for SIRT1 knockdown and SRT1720 treatment for its activation,the expression levels of SIRT1,CHOP,glucose regulated protein 78(GRP78),and activating transcription factor 4(ATF4)were *** potential reversal of SIRT1 knockdown effects by 4-phenyl butyric acid(4-PBA;an ER stress inhibitor)was *** vivo,age-related cataract(ARC)rat models were induced by sodium selenite injection,and the protective role of SIRT1,activated by SRT1720 intraperitoneal injections,was evaluated through morphology observation,hematoxylin and eosin(H&E)staining,Western blotting,and ***:SIRT1 expression was downregulated in TMinduced SRA01/04 ***,in SRA01/04 cells,both cell apoptosis and CHOP expression increased with the rising doses of *** stress was stimulated by TM,as evidenced by the increased GRP78 and ATF4 in the SRA01/04 cell apoptosis *** of SIRT1 by siRNA knockdown increased ER stress activation,whereas SRT1720 treatment had opposite results.4-PBA partly reverse the adverse effect of SIRT1 knockdown on *** vivo,SRT1720 attenuated the lens opacification and weakened the ER stress activation in ARC rat ***:SIRT1 plays a protective role against TM-induced apoptosis in HLECs and slows the progression of cataract in

关键词： silent information regulator factor 2-related enzyme 1 endoplasmic reticulum stress apoptosis human lens epithelial cells cataract

Multifaceted role of microRNAs in gastric cancer stem cells: Mechanisms and potential biomarkers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2024年第2期16卷 300-313页

作者： Qian-hui Sun zi-Yu Kuang Guang-hui Zhu Bao-Yi Ni Jie Li Department of Oncology Guang'anmen HospitalChina Academy of Chinese Medical SciencesBeijing 100053China Graduate College Beijing University of Traditional Chinese MedicineBeijing 100029China Department of Oncology Heilongjiang University of Chinese MedicineHarbin 150040Heilongjiang ProvinceChina

MicroRNAs(miRNAs)have received much attention in the past decade as potential key epigenomic regulators of tumors and cancer stem cells(CSCs).The abnormal expression of miRNAs is responsible for different phenotypes of gastric cancer stem cells(GCSCs).Some specific miRNAs could be used as promising biomarkers and therapeutic targets for the identification of *** review summarizes the coding process and biological functions of miRNAs and demon-strates their role and efficacy in gastric cancer(GC)metastasis,drug resistance,and apoptosis,especially in the regulatory mechanism of *** shows that the overexpression of onco-miRNAs and silencing of tumor-suppressor miRNAs can play a role in promoting or inhibiting tumor metastasis,apart from the initial formation of *** also discusses the epigenetic regulation and potential clinical applications of miRNAs as well as the role of CSCs in the pathogenesis of *** believe that this review may help in designing novel therapeutic approaches for GC.

关键词： Gastric cancer,Cancer stem cells MicroRNAs Epigenetics Therapeutic target

Asymptotic Inference in the Random Coefficient Autoregressive Model with Time-functional Variance Noises

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2024年第2期40卷 320-346页

作者： En-wen ZHU zi-wei DENG Han-jun ZHANG Jun CAO Xiao-hui LIU Department of Mathematics and Statistics Changsha University of Science and TechnologyChangsha 410114China School of Mathematics and Computational Science Xiangtan UniversityXiangtan 411105China School of Statistics and Data Science and Key Laboratory of Data Science in Finance and EconomicsJiangxi University of Finance and EconomicsNanchang 330013China

This paper considers the random coefficient autoregressive model with time-functional variance noises,hereafter the RCA-TFV *** first establish the consistency and asymptotic normality of the conditional least squares estimator for the constant *** semiparametric least squares estimator for the variance of the random coefficient and the nonparametric estimator for the variance function are constructed,and their asymptotic results are reported.A simulation study is presented along with an analysis of real data to assess the performance of our method in finite samples.

关键词： random coefficient autoregressive model time-functional variance conditional least squares semiparametric least squares

Analysis of mechanical strengths of extreme line casing joint considering geometric, material, and contact nonlinearities

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 1992-2004页

作者： Ji-Yun Zhang chi Peng Jian-Hong Fu Quan Cao Yu Su Jian-Yun Pang zi-Qiang Yu Petroleum Engineering School Southwest Petroleum UniversityChengdu610500SichuanChina Engineering Technology Research Institute of CNPC Southwest Oil and Gas Field Company Chengdu610017SichuanChina

To address the challenges associated with difficult casing running,limited annular space,and poor cementing quality in the completion of ultra-deep wells,the extreme line casing offers an effective solution over conventional ***,due to its smaller size,the joint strength of extreme line casing is reduced,which may cause failure when running in the *** address this issue,this study focuses on the CST-ZTΦ139.7 mm×7.72 mm extreme line casing and employs the elastic-plastic mechanics to establish a comprehensive analysis of the casing joint,taking into account the influence of geometric and material nonlinearities.A finite element model is developed to analyze the forces and deformations of the extreme line casing joint under axial tension and external collapse *** model investigates the stress distribution of each thread tooth subjected to various tensile forces and external ***,the tensile strength and crushing strength of the extreme line casing joint are determined through both analytical and experimental *** findings reveal that,under axial tensile load,the bearing surface of each thread tooth experiences uneven stress,with relatively high equivalent stress at the root of each thread *** end thread teeth are valuable spots for *** is observed that the critical fracture axial load of thread decreases linearly with the increase of thread tooth *** external pressure,the circumferential stress is highest at the small end of the external thread,leading to yield *** tensile strength of the joint obtained from the finite element model exhibits a relative error of less than 7%compared to the analytical and experimental values,proving the reliability of the finite element *** tensile strength of the joint is 3091.9 k ***,in terms of anti-collapse capability,the joints demonstrate higher resistance to collapse compared to the casing body,which is consistent with the test resul

关键词： Extreme line casing Elastic-plastic mechanics Finite element analysis Tensile strength Collapse strength

Regulatory factors of Nrf2 in age-related macular degeneration pathogenesis

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2024年第7期17卷 1344-1362页

作者： zi-Ling Hu Yu-Xuan Wang zi-Yue Lin Wen-Shuo Ren Bo Liu hui Zhao Qiong Qin Five Year Program of Ophthalmology and Optometry 2019 Beijing Tong Ren HospitalCapital Medical UniversityBeijing 100054China Four Year Program of Traditional chinese Pharmacy 2020 School of Traditional Chinese MedicineCapital Medical UniversityBeijing 100069China School of Traditional chinese Medicine Capital Medical UniversityBeijing 100069China Beijing Key Laboratory of TCM Collateral Disease Theory Research Beijing 100069China Five Year Program of Ophthalmology and Optometry 2021 School of Basic Medical SciencesCapital Medical UniversityBeijing 100069China Biochemistry&Molecular Biology School of Basic Medical SciencesCapital Medical UniversityBeijing 100069China

Age-related macular degeneration(AMD)is a complicated disease that causes irreversible visual *** evidences pointed retinal pigment epithelia(RPE)cells as the decisive cell involved in the progress of AMD,and the function of anti-oxidant capacity of PRE plays a fundamental physiological *** factor erythroid 2 related factor 2(Nrf2)is a significant transcription factor in the cellular anti-oxidant system as it regulates the expression of multiple anti-oxidative *** functions of protecting RPE cells against oxidative stress(OS)and ensuing physiological changes,including inflammation,mitochondrial damage and autophagy dysregulation,have already been *** the roles of upstream regulators of Nrf2 could provide further insight to the OS-mediated AMD *** the first time,this review summarized the reported upstream regulators of Nrf2 in AMD pathogenesis,including proteins and miRNAs,and their underlying molecular mechanisms,which may help to find potential targets via regulating the Nrf2 pathway in the future research and further discuss the existing Nrf2 regulators proved to be beneficial in preventing AMD.

关键词： Nrf2 upstream regulators retinal pigment epithelia age-related macular degeneration oxidative stress