检索结果-南通市图书馆

Rietveld refinement and optical properties of srWO_4:Eu^(3+) powders prepared by the non-hydrolytic sol-gel method

Journal of Rare Earths 2015年第2期33卷 113-128页

作者： p.f.s.pereira I.C.Nogueira E.Longo E.J.Nassar I.L.V.Rosa L.s.Cavalcante Chemistry Institute University of the State of Sao Paulo Julio de Mesquita Filho-UNESP Francisco DegniAraraquara-SP 14800-900 Brazil LIEC-Chemistry Department Federal University of Sao Carlos Via Washington Luis Km 235Sao Carlos-SP 13565-905 Brazil University of franca-UNIfRAN Via Dr.Armando Sales de OliveiraNo.201 Franca-SP 14404-600 Brazil CCN-DQ-GERATEC University of the State of Piauí Joao Cabral 2231 P.O.Box 391Terezina PI 64002-150 Brazil

We investigated the effect of annealing time on the structure and optical properties of sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 *** and differential thermal analyses revealed that sr WO4：Eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and Rietveld refinement data confirmed that all powders had a scheelite-type tetragonal ***-Raman and fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]*** properties were investigated by ultraviolet-visible（UV-vis）diffuse reflectance,and photoluminescence（pL）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of sr WO4：Eu^3＋ *** properties validated that the Eu^3＋ electric-dipole（^5D0→^7f2）transition in pL emission spectra was dominant which proved that Eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7f2）/（^5D0→^7f1）]band ratios showed that Eu^3＋ ions were located in a low symmetry *** pL emission,ηandτproved the dependence on the annealing time in the behavior of sr WO4：Eu3＋powders with a higher relative emission pL intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h.

关键词： srWO4 Rietveld refinement optical band gap Eu^(3+) +-rare earth luminescence

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Rotating effects on the photoionization cross-section of a 2D quantum ring

引用

Communications in Theoretical physics 2024年第10期76卷 153-159页

作者： Carlos Magno O pereira frankbelson dos s Azevedo Luís fernando C pereira Edilberto O silva Departamento de física Universidade Federal do Maranh?o

In this article, we investigate the nonrelativistic quantum motion of a charged particle within a rotating frame, taking into account the Aharonov–Bohm(AB) effect and a uniform magnetic field. Our analysis entails the derivation of the equation of motion and the corresponding radial equation to describe the system. solving the resulting radial equation enables us to determine the eigenvalues and eigenfunctions, providing a clear expression for the energy levels. furthermore,our numerical analysis highlights the substantial influence of rotation on both energy levels and optical properties. specifically, we evaluate the photoionization cross-section with and without the effects of rotation. To elucidate the impact of rotation on the photoionization process of the system, we present graphics that offer an appealing visualization of the intrinsic nature of the physics involved.

关键词： Aharonov-Bohm effect photoionization cross-section quantum ring rotating effect

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Temporal and spatial differences in human activities performed in Urban Green spaces of Vilnius(Lithuania)

引用

Geography and sustainability 2024年第2期5卷 302-317页

作者： Luís Valença pinto Carla sofia santos ferreira paulo pereira Research Centre for Natural Resources Environment and society(CERNAs) Polytechnic Institute of CoimbraBencanta3045-601 CoimbraPortugal Environmental Management Laboratory Mykolas Romeris UniversityVilniusLithuania polytechnic Institute of Coimbra Applied Research InstituteRua da MisericórdiaLagar dos Cortiços-S.Martinho do Bispo3045-093 CoimbraPortugal

Urban green spaces(UGs)are relevant to city well-being,as recognized by the United Nations’sustainable Development Goals(sDGs).However,few studies have studied the temporal use of *** work assessed the seasonal,weekly,and daily use of three urban green spaces(Vingis park,Bernardino Garden,and Jomantas park)in Vilnius(Lithuania).The study is based on an on-site observation-based survey,which recorded users’characteristics,activities,and weather conditions during summer and *** results showed that UGs’s seasonal,weekly,and daily use differed according to park and users’*** with a higher diversity of facilities had a high seasonal difference in the number of observed *** numbers were higher in the summer for activities with children,social activities,sports,and water activities than in the *** park had the lowest variability in user *** variables were linked to changes in users’*** precipitation and lower temperature were associated with reducing the number of users and the diversity of registered *** of the stationary activities were observed during *** diversity of the observed activities was associated with the available facilities rather than the park *** distribution of stationary activities was spatially correlated with facility/equipment(benches,playgrounds,sports,and fitness equipment)and proximity to water *** results of this study are relevant for UGs design,planning,and management.

关键词： Urban parks seasonal differences Temporal use Time of day spatial distribution of UGs users

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Artemisia vulgaris Induces Tumor-selective ferroptosis and Necroptosis via Lysosomal Ca^(2+) signaling

引用

Chinese Journal of Integrative Medicine 2024年第6期30卷 525-533页

作者： Lucas dos santos Zamarioli Michele Rosana Maia santos Adolfo Garcia Erustes Vanessa Marques Meccatti Thais Cristine pereira soraya s smaili Maria Cristina Marcucci Carlos Rocha Oliveira Gustavo Js pereira Claudia Bincoletto Department of pharmacology Paulista School of MedicineFederal University of São PauloSão PauloSP04044-020Brazil Research Group on phytocomplexes and Cell signaling School of Health SciencesAnhembi Morumbi UniversitySão PauloSP03164-000Brazil Department of Biosciences and Oral Diagnosis Institute of Science and TechnologySão Paulo State University(ICT-UNESP)São PauloSP12231-280Brazil

Objective To evaluate the chemical composition and effects of Artemisia vulgaris(AV)hydroalcoholic extract(HEAV)on breast cancer cells(MCf-7 and sKBR-3),chronic myeloid leukemia(K562)and NIH/3T3 *** phytochemical analysis of HEAV was done by high-performance liquid chromatography-mass(HpLC)*** and cell death studies were performed using trypan blue and Annexin/fITC-7AAD,***-1(fer-1)and necrostatin-1(Nec-1)were used to assess the mode of HEAV-induced cell death and acetoxymethylester(BApTA-AM)was used to verify the involvement of cytosolic calcium in this *** calcium measurements were made using *** HEAV decreased the viability of MCf-7,sKBR-3 and K562 cells(pf HEAV-treated K562 cells was reduced compared to HEAV-exposed fibroblasts(pf K562 cells with HEAV induced cell death primarily by late apoptosis and necrosis in assays using annexin V-fITC/7-AAD(pse of Nec-1 and fer-1 increased the viability of K562 cells treated with HEAV relative to cells exposed to HEAV alone(pse mainly from lysosomes in K562 cells(pfurthermore,BApTA-AM,an intracellular Ca^(2+)chelator,decreased the number of non-viable cells treated with HEAV(psions HEAV is cytotoxic and activates several modalities of cell death,which are partially dependent on lysosomal release of Ca^(2+).These effects may be related to artemisinin and caffeoylquinic acids,the main compounds identified in HEAV.

关键词： Artemisia vulgaris necroptosis ferroptosis late apoptosis Ca^(2+)signaling

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated phase change materials in latent heat thermal energy storage systems

引用

Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1051-1070页

作者： p.s.REDDY p.sREEDEVI Department of Mathematics Rajeev Gandhi Memorial College of Engineering and TechnologyNandyal 518501India

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEpCMs).The versatile finite element method(fEM)is implemented to numerically solve the governing *** effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEpCMs,ranging from 2%to 6%,the stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity ***,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented *** results indicate that the time taken by the NEpCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf ***,the contours of the heat capacity ratio Cr decrease with the increase in the stefan number ste.

关键词： volume fraction of nano-encapsulated phase change material(NEpCM) radiation stefan number heat capacity ratio entropy generation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Carbon Monoxide as C1 Building Block in fine Chemical synthesis

引用

Chinese Journal of Chemistry 2024年第2期42卷 199-221页

作者： Rui M.B.Carrilho Mario J.f.Calvete Gabor Mikle Laszlo Kollar Mariette M.pereira University of Coimbra Coimbra Chemistry CentreDepartment of ChemistryRua Larga3004-535 CoimbraPortugal Department of General and Inorganic Chemistry and ELKH-pTE Research Groupfor selective Chemical syntheses University of PecsIfjusag utja 6H-7624 PecsHungary

Carbon monoxide(CO)has become one of the most relevant and versatile renewable C1 building blocks for chemical synthesis,especially in the fine chemicals industry,due to the development of efficient and selective catalysts for its *** this review,we present a comprehensive critical analysis of the last 10 years literature on the use of CO as a renewable feedstock for fine chemicals *** review is organized by type of catalytic reaction,namely alkene and alkyne carbonylation,hydroformylation,carbonylation of aryl halides,carbonylative cross-coupling and C-H *** examples of the synthesis of relevant building blocks and/or known pharmaceuticals are *** is placed on examples of utilizing CO as the C1 building block in one or more catalytic *** catalyst used and the reaction conditions are consistently presented throughout all of the examples.

关键词： Carbon monoxide fine chemicals Carbonylation Hydroformylation C-H functionalization

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Towards efficient strain engineering of 2D materials:A four-points bending approach for compressive strain

引用

Nano Research 2024年第6期17卷 5317-5325页

作者： Hao Li félix Carrascoso Ana Borrás Gloria p.Moreno francisco J.Aparicio Ángel Barranco Andrés Castellanos Gómez Campus de Cantoblanco Instituto de Ciencia de Materiales de MadridC.Sor Juana Inés de la Cruz328049 MadridSpain Nanotechnology on surfaces and plasma Lab Instituto de Ciencia de Materiales de Sevilla(CSIC-Universidad de Sevilla).C/Americo Vespucio 49E-41092 SevilleSpain Departamento de física Aplicada I Escuela Politécnica SuperiorUniversidad de Sevillac/Virgen deÁfrica 7E-41011 SevilleSpain

strain engineering,as a powerful strategy to tune the optical and electrical properties of two-dimensional(2D)materials by deforming their crystal lattice,has attracted significant interest in recent years.2D materials can sustain ultra-high strains,even up to 10%,due to the lack of dangling bonds on their surface,making them ideal brittle *** remarkable mechanical resilience,together with a strong strain-tunable band structure,endows 2D materials with a broad optical and electrical response upon ***,strain engineering based on 2D materials is restricted by their nanoscale and strain quantification *** this study,we have modified a homebuilt three-points bending apparatus to transform it into a four-points bending apparatus that allows for the application of both compressive and tensile strains on 2D *** approach allows for the efficient and reproducible construction of a strain system and minimizes the buckling effect caused by the van der Waals interaction by adamantane encapsulation *** results demonstrate the feasibility of introducing compressive strain on 2D materials and the potential for tuning their optical and physical properties through this approach.

关键词： uniaxial compressive strain polymer encapsulation differential reflectance spectroscopy exciton tunability

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Development of an ultrathin liquid sheet target for laser ion acceleration at high repetition rates in the kilohertz range

引用

High power Laser science and Engineering 2024年第3期12卷 134-145页

作者： M.füle A.p.Kovács T.Gilinger M.Karnok p.Gaál s.figul G.Marowsky K.Osvay National Laser-Initiated Transmutation Laboratory University of SzegedSzegedHungary Department of Experimental physics University of SzegedSzegedHungary ELI ALps ELI-HU Non-Profit Ltd.SzegedHungary Department of Optics and Quantum Electronics University of SzegedSzegedHungary Advanced Microfluidic systems GmbH GöttingenGermany

A colliding microjet liquid sheet target system was developed and tested for pairs of round nozzles of 10,11 and 18μm in *** sheet's position stability was found to be better than a few *** interaction with 50 mJ laser pulses,the 18μm jet has a resonance amplitude of 16μm at a repetition rate of 33 Hz,while towards 100 Hz it converges to 10μm for all nozzles.A white-light interferometric system was developed to measure the liquid sheet thickness in the target chamber both in air and in vacuum,with a measurement range of 182 nm±1μm and an accuracy of±3%.The overall shape and 3D shape of the sheet follow the Hasson±peck model in *** vacuum versus air,the sheet gradually loses 10%of its thickness,so the thinnest sheet achieved was below 200 nm at a vacuum level of 10±4mbar,and remained stable for several hours of operation.

关键词： diagnostics laser ion acceleration nanometric liquid sheet targets vacuum test

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of preterm birth on the association between gestational diabetes mellitus and childhood developmental vulnerability:a causal mediation analysis

引用

World Journal of pediatrics 2024年第1期20卷 54-63页

作者： Bereket Duko Amanuel Tesfay Gebremedhin Gizachew Assefa Tessema Gavin pereira Australian Centre for precision Health UniSA Clinical and Health SciencesUniversity of South AustraliaNorth TerraceAdelaideSA5000Australia Curtin school of population Health Faculty of Health SciencesCurtin UniversityKent StreetBentleyWA 6102Australia enAble Institute Curtin UniversityKent StreetBentleyWA6102Australia Centre for fertility and Health(CefH) Norwegian Institute of Public HealthOsloNorway

Background Epidemiological studies examining the direct and indirect effects of gestational diabetes mellitus(GDM)on offspring early childhood developmental vulnerability are ***,the aims of this study were to estimate the direct and indirect effects of GDM(through preterm birth)on early childhood developmental *** We conducted a retrospective population-based cohort study on the association between gestational diabetes mellitus and early childhood developmental vulnerability in children born in Western Australia(WA)using maternal,infant and birth records from the Midwives Notification,Hospitalizations,Developmental Anomalies,and the Australian Early Development Census(AEDC)*** used two aggregated outcome measures:developmentally vulnerable on at least one AEDC domain(DV1)and developmentally vulnerable on at least two AEDC domains(DV2).Causal mediation analysis was applied to estimate the natural direct(NDE),indirect(NIE),and total(TE)effects as relative risks(RR).Results In the whole cohort(n=64,356),approximately 22%were classified as DV1 and 11%as DV2 on AEDC *** of the natural direct effect suggested that children exposed to GDM were more likely to be classified as DV1(RR=1.20,95%CI:1.10-1.31)and DV2(RR=1.34,95%CI:1.19-1.50)after adjusting for potential *** 6%and 4%of the effect of GDM on early childhood developmental vulnerability was mediated by preterm birth for DV1 and DV2,*** Children exposed to gestational diabetes mellitus were more likely to be developmentally vulnerable in one or more AEDC *** biological mechanism for these associations is not well explained by mediation through preterm birth.

关键词： Child development Causal mediation analysis Gestational diabetes mellitus Offspring

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

On the analytical solution of transient friction in channel flows

引用

Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1447-1466页

作者： f.J.GARCíA-GARCíA p.fARINAs-ALVARINO Department of Naval&Industrial Engineering Polytechnic School of EngineeringUniversity of A CorunaCampus Industrial de FerrolFerrol 15403A CorunaSpain Integraciones Técnicas de seguridad S.A.Pol.Ind.Espiritu SantoC/Nobel15Cambre 15650A CorunaSpain

The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULf)and the purely turbulent component(pTC),and the contributions are analyzed separately by theoretical *** is found that,the transient friction may be higher or remarkably lower than that in equal-Reynolds number steady-state *** universal time constant for plane-parallel laminar flows is reported,and the role of the time constant in a turbulent mean flow is *** is shown that the time constant is related to the turbulence's frozen ***,a study of the logarithmic layer during the transient flow is accomplished,which shows that the logarithmic layer is destroyed.

关键词： transient friction transient flow unsteady channel flow

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：