检索结果-南通市图书馆

Yb-and Er concentration dependence of the upconversion luminescence of highly doped NaYf_(4):Yb,Er/NaYf_(4):Lu core/shell nanocrystals prepared by a water-free synthesis

引用

Nano Research 2022年第10期15卷 9639-9646页

作者： Christian Würth Bettina Grauel Monika Pons florian frenzel Philipp Rissiek Kerstin Rücker markus Haase Ute Resch-Genger federal Institute for Materials Research and Testing(BAM) Division BiophotonicsRichard-Willstaetter-Str.1112489 BerlinGermany Institut für Chemie Neuer Materialien Fachbereich Biologie/ChemieUniversität OsnabrückBarbarastraße 749076 OsnabrückGermany

High sensitizer and activator concentrations have been increasingly examined to improve the performance of multi-color emissive upconversion(UC)nanocrystals(UCNC)like NaYf_(4):Yb,Er and first strategies were reported to reduce concentration quenching in highly doped *** luminescence(UCL)is,however,controlled not only by dopant concentration,yet by an interplay of different parameters including size,crystal and shell quality,and excitation power density(P).Thus,identifying optimum dopant concentrations requires systematic studies of UCNC designed to minimize additional quenching pathways and quantitative ***,we quantify the dopant concentration dependence of the UCL quantum yield(ΦUC)of solid NaYf_(4):Yb,Er/NaYf_(4):Lu upconversion core/shell nanocrystals of varying Yb3+and Er3+concentrations(Yb3+series:20%‒98%Yb3+;2%Er3+;Er3+series:60%Yb3+;2%‒40%Er3+).To circumvent other luminescence quenching processes,an elaborate synthesis yielding OH-free UCNC with recordΦUC of~9%and~25 nm core particles with a thick surface shell were *** Yb3+concentrations barely reduceΦUC from~9%(20%Yb3+)to~7%(98%Yb3+)for an Er3+concentration of 2%,thereby allowing to strongly increase the particle absorption cross section and UCNC *** an increased Er3+concentration reducesΦUC from~7%(2%Er3+)to 1%(40%)for 60%Yb3+.Nevertheless,at very high P(>1 MW/cm^(2))used for microscopic studies,highly Er3+-doped UCNC display a high brightness because of reduced *** findings underline the importance of synthesis control and will pave the road to many fundamental studies of UC materials.

关键词： highly doped upconversion nanocrystals core/shell nanoparticles upconversion luminescence efficiency NaYf_(4):Yb Er concentration quenching

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

Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals

引用

Nano Research 2022年第3期15卷 2362-2373页

作者： Bettina Grauel Christian Würth Christian Homann Lisa Krukewitt Elina Andresen Janina Roik Sebastian Recknagel markus Haase Ute Resch-Genger federal Institute for Materials Research and Testing(BAM) Division 1.2 BiophotonicsRichard-Willstaetter-Str.1112489 BerlinGermany federal Institute for Materials Research and Testing(BAM) Division 1.6 Inorganic Reference MaterialsRichard-Willstaetter-Str.1112489 BerlinGermany Institute of Chemistry of New Materials Department Biology/ChemistryUniversity OsnabrueckBarbarastr.749076 OsnabrueckGermany Department of Anesthesiology and Intensive Care Medicine University Medical Center RostockSchillingallee 3518057 RostockGermany

Despite considerable advances in synthesizing high-quality core/shell upconversion(UC)nanocrystals(NC;UCNC)and UCNC photophysics,the application of near-infrared(NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence(UCL)of UCNC of small size or thin protecting *** obtain deeper insights into energy transfer and surface quenching processes involving Yb^(3+) and Er^(3+) ions,we examined energy loss processes in differently sized solid core NaYf_(4) nanocrystals doped with either Yb^(3+)(YbNC;20%Yb^(3+))or Er^(3+)(ErNC;2%Er^(3+))and co-doped with Yb^(3+) and Er^(3+)(YbErNC;20%Yb^(3+) and 2%Er^(3+))without a surface protection shell and coated with a thin and a thick NaYf_(4) shell in comparison to single and co-doped bulk *** studies at 375 nm excitation demonstrate back-energy transfer(BET)from the ^(4)G_(11/2) state of Er^(3+) to the ^(2)f_(5/2) state of Yb^(3+),through which the red Er^(3+) ^(4)f_(9/2) state is efficiently *** power density(P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and three-photonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+*** intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC *** provide a three-dimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC.

关键词： upconversion luminescence core/shell nanoparticles dopant concentration lifetime volume effect surface quenching

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

Genetic composition,genetic diversity and small-scale environmental variation matter for the experimental reintroduction of a rare plant

引用

Journal of Plant Ecology 2016年第6期9卷 805-813页

作者： Daniel Prati markus Peintinger markus fischer Institute of Plant Sciences University of BernAltenbergrain 21CH-3013 BernSwitzerland Oeschger Centre for Climate Change Research University of BernZähringerstrasse 25CH-3012 BernSwitzerland WSL-Eidgenössische forschungsanstalt für Wald Schnee und LandschaftZürcherstrasse 111CH-8903 BirmensdorfSwitzerland

Aims Reintroduction has become an important tool for the management of endangered plant *** tested the little-explored effects of small-scale environmental variation,genotypic composition(*** of genotypes)and genotypic diversity on the population survival of the regionally rare clonal plant Ranunculus *** this species of periodically inundated lakeshores,genetic differentiation had been reported between populations and between short-flooded and long-flooded microsites within *** We established 306 experimental test populations at a previously unoccupied lakeshore,comprising either monocultures of 32 genotypes,mixtures of genotypes within populations or mixtures of genotypes between *** 2000,three years after planting out at the experimental site,a long-lasting flood caused the death of half of the experimental *** 2003,an extreme drought resulted in the lowest summer water levels ever *** findings Despite these climatic extremes,27%of the established populations survived in December *** success of experimental populations largely differed between ***,the success of genotype monocultures depended on genotype and source *** differentiation between microsites played a minor role for the success of *** the flood,populations planted with genotypes from different source populations increased in abundance,whereas populations with genotypes from single source populations and genotype monocultures *** 2014,several small patches of Ranunculus clones were still present,but plants were strongly intermingled,which precluded their assignment to the original *** conclude that sources for reintroductions need to be selected ***,mixtures of plants from different populations appear to be the best choice for successful reintroduction,at least in unpredictably varying environments.

关键词： conservation management global change lakeshore Ranunculus reptans

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

Millijoule ultrafast optical parametric amplification as replacement for high-gain regenerative amplifiers

引用

High Power Laser Science and Engineering 2023年第4期11卷 33-44页

作者： Yannik Zobus Christian Brabetz Johannes Hornung Jonas BOhland Dirk Reemts Ji-Ping Zou markus Loeser Daniel Albach Ulrich Schramm Vincent Bagnoud Technische Universität Darmstadt DarmstadtGermany GSI Helmholtzzentrum für Schwerionenforschung GmbH DarmstadtGermany Laboratoire pour l’Utilisation des Lasers Intenses CNRSEcole PolytechniquePalaiseauFrance Helmholtz-Zentrum Dresden-Rossendorf DresdenGermany Technische Universität Dresden DresdenGermany Helmholtz-Institut Jena JenaGermany

We report on the development of an ultrafast optical parametric amplifier front-end for the Petawatt High Energy Laser for heavy Ion eXperiments(PHELIX)and the Petawatt ENergy-Efficient Laser for Optical Plasma Experiments(PEnELOPE)*** front-end delivers broadband and stable amplification up to 1 mJ per pulse while maintaining a high beam *** implementation at PHELIX allowed one to bypass the front-end amplifier,which is known to be a source of *** the bypass,an amplified spontaneous emission contrast of 4.9×10^(−13)and a pre-pulse contrast of 6.2×10^(−11)could be *** to its high stability,high beam quality and its versatile pump amplifier,the system offers an alternative for high-gain regenerative amplifiers in the front-end of various laser systems.

关键词： high-intensity laser temporal laser contrast ultrafast optical parametric amplification

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

Long-term reconstruction of flash floods in the Qilian Mountains,China,based on dendrogeomorphic methods

引用

Journal of Mountain Science 2022年第11期19卷 3163-3177页

作者： QIE Jia-zhi ZHANG Yong TRAPPMANN Daniel ZHONG Yi-hua BALLESTEROS-CÁNOVAS Juan Antonio fAVILLIER Adrien STOffEL markus Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Climate Change Impacts and Risks in the Anthropocene(C-CIA) Institute for Environmental SciencesUniversity of GenevaGeneva CH-1205Switzerland Dendrolab.ch Department of Earth SciencesUniversity of GenevaGeneva CH-1205Switzerland National Museum of Natural Sciences MNCN-CSICC/Serrano 115bis28006MadridSpain Department f.-A.forel for Environmental and Aquatic Sciences University of GenevaGeneva CH-1205Switzerland

In China,flash floods are one of the main natural disasters causing loss of life and damage to *** threat of flash floods is exacerbated with climate change and increased human activities,such that the number of disasters has shown a clear upward trend in recent ***,due to the scarcity of instrumental data or overly short timeseries,we are still lacking critical data to understand spatio-temporal patterns and driving factors of extreme flash *** missing knowledge is however crucial for a proper management of these hazards,especially in remote mountain *** forested catchments,dendrogeomorphology allows the reconstruction of past process activity based on growth disturbances(GDs)in trees that have been affected by past flash ***,in our study,for the first time,we reconstruct past flash floods in the Qilian Mountains,northeast Tibetan Plateau,over past *** this end,we sampled 99 Qinghai spruce(Picea crassifolia)trees affected by flash floods,with a total of 194increment cores,and identified 302 GDs induced by past flash *** GDs have been caused by at least 21 flash floods that we are able to reconstruct over the last 170 *** position of GDs within tree rings and the intra-seasonal dating of past events also allowed discussion of the likely synoptic situations that may have led to the triggering of flash floods in the *** regression analysis confirms that significant correlation exists between cumulative maximum 5-day August-September precipitation and reconstructed flash floods,which is corresponding to the majority of scars and related tangential rows of traumatic resin ducts(TRDs)found in the latewood portion of growth *** results support the idea that abundant precipitation occurring at the end of the summer season and early fall is the key factor driving flash floods in our study *** research not only fills the gaps regarding historical flash flood histories in

关键词： Tree ring Dendrogeomorphology flash floods Qinghai spruce Qilian Mountains

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

t-Private and t-Secure Auctions

引用

Journal of Computer Science & Technology 2008年第5期23卷 694-710页

作者： markus Hinkelmann Andreas Jakoby Peer Stechert Institut für Theoretische Informatik Universitt zu Lübeck Germany fachgruppe Didaktik der Informatik und E-Learning Universitt Siegen Germany

In most of the auction systems the values of bids are known to the auctioneer. This allows him to manipulate the outcome of the auction. Hence, one might be interested in hiding these values. Some cryptographically secure protocols for electronic auctions have been presented in the last decade. Our work extends these protocols in several ways. On the basis of garbled circuits, i.e., encrypted circuits, we present protocols for sealed-bid auctions that fulfill the following requirements： 1） protocols are information-theoretically t-private for honest but curious parties; 2） the number of bits that can be learned by malicious adversaries is bounded by the output length of the auction; 3） the computational requirements for participating parties are very low： only random bit choices and bitwise computation of the XOR-function are necessary. Note that one can distinguish between the protocol that generates a garbled circuit for an auction and the protocol to evaluate the auction. In this paper we address both problems. We will present a t-private protocol for the construction of a garbled circuit that reaches the lower bound of 2t ＋ 1 parties, and finally, we address the problem of bid changes in an auction. a more randomness efficient protocol for （t ＋ 1）^2 parties

关键词： multi-party private and secure computation garbled circuits private auctions

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

High-Performance 3D Li-B-C-Al Alloy Anode and its Twofold Li Electrostripping and Plating Mechanism Revealed by Synchrotron X-Ray Tomography

引用

Energy & Environmental Materials 2023年第3期6卷 247-256页

作者： fengcheng Tang Xia Zhang markus Osenberg Chao Yang Haifeng Huang Andr Hilger Masyuki Uesugi Kentaro Uesug Akihisa Takeuchi Ingo Manke fu Sun Libao Chen State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of SciencesQingdao 266101China Helmholtz-Zentrum Berlin für Materialien und Energie 14109 Berlin Germany College of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China Japan Synchrotron Radiation Research Institute(JASRI)/Spring-8 Sayo-gun Hyogo 679-5198Japan

The uncontrollable Li electrostripping and plating process that results in dendritic Li growth and huge volume change of Li anode limits the practicality of Li metal batteries(LMBs).To simultaneously address these issues,designing three-dimensional(3D),lithiophilic and mechanically robust electrodes seems to be one of the cost-effective ***,a new 3D Li-B-C-Al alloy anode is designed and *** prepared 3D alloy anode exhibits not only superior lithiophilicity that facilitates uniform Li nucleation and growth but also sufficient mechanical stability that maintains its structural *** performance of the prepared 3D alloy is demonstrated through comprehensive electrochemical *** addition,non-destructive and 3D synchrotron X-ray computed tomography(SX-CT)technique is employed to investigate the underlying working mechanisms of the prepared alloy anode.A unique twofold Li electrostripping and plating mechanism under different electrochemical cycling conditions is ***,improved performance of the full cells built with the 3D alloy anode and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathode corroborate its potential application ***,the current work not only showcases the superiority of the 3D alloy as potential anode material for LMBs but also provides fundamental insights into its underlying working mechanisms that may further propel its research and development.

关键词： Li alloy Li metal anode Li metal battery Li-B-C-Al plating

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

Ultrahigh numerical aperture meta-fibre for flexible optical trapping

引用

Light(Science & Applications) 2021年第4期10卷 589-599页

作者： Malte Plidschun Haoran Ren Jisoo Kim Ronny forster Stefan A.Maier markus A.Schmidt Leibniz Institute of Photonic Technology 07745 JenaGermany Abbe Center of Photonics and faculty of Physics FSU Jena07745 JenaGermany Chair in Hybrid Nanosystems Nanoinstitute MunichLMU Munchen80539 MunchenGermany Department of Physics Imperial College LondonLondon SW72AZUK Otto Schott Institute of Material Research FSU Jena07745 JenaGermany

Strong focusing on diffraction-limited spots is essential for many photonic applications and is particularly relevant for optical trapping;however,all currently used approaches fail to simultaneously provide flexible transportation of light,straightforward implementation,compatibility with waveguide circuitry,and strong ***,we demonstrate the design and 3D nanoprinting of an ultrahigh numerical aperture meta-fibre for highly flexible optical *** into account the peculiarities of the fibre environment,we implemented an ultrathin meta-lens on the facet of a modified single-mode optical fibre via direct laser writing,leading to a diffraction-limited focal spot with a recordhigh numerical aperture of up to NA≈*** unique capabilities of this flexible,cost-effective,bio-and fibre-circuitrycompatible meta-fibre device were demonstrated by optically trapping microbeads and bacteria for the first time with only one single-mode fibre in combination with diffractive *** study highlights the relevance of the unexplored but exciting field of meta-fibre optics to a multitude of fields,such as bioanalytics,quantum technology and life sciences.

关键词： optical waveguide fibre

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

Relation between half-cell and fuel cell activity and stability of feNC catalysts for the oxygen reduction reaction

引用

SusMat 2022年第5期2卷 630-645页

作者： Janik Scharf markus Kübler Vladislav Gridin William David Zacharias Wallace Lingmei Ni Stephen Daniel Paul Ulrike Ingrid Kramm Department of Chemistry Catalysts and ElectrocatalystsTechnical University of DarmstadtDarmstadtGermany Department of Materials and Earth Sciences Catalysts and ElectrocatalystsTechnical University of DarmstadtDarmstadtGermany BMW Group Munich MunichGermany

feNC catalysts are promising substitutes of platinum-type catalysts for the oxygen reduction reaction(ORR).While previous research disclosed that high pyrolysis temperatures are required to achieve good stability,it was identified that a trade-off needs to be made regarding the active site *** central question is,if a good stability can also be reached at milder pyrolysis conditions but longer duration retaining more active sites,while enabling the defect-rich carbon to heal during a long residence time?To address this,a variation of pyrolysis temperatures and durations is used in feNC *** morphology and iron species are characterized by Raman spectroscopy and Mössbauer spectroscopy,*** cell(fC)activity and stability data are *** results are compared to ORR activity and selectivity data from rotating ring disc electrode experiments and resulting durability in accelerated stress tests mimicking the load cycle and start-up and shut-down cycle *** is discussed how pyrolysis temperature and duration affect fC activity and ***,more important,the results connect the pyrolysis conditions to the required accelerated stress test protocol combination to enable a prediction of the catalyst stability in fuel cells.

关键词： accelerated stress tests feNC catalysts fuel cells Mössbauer spectroscopy oxygen reduction reaction

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

The Relationship between Dimensions of Emerging Adulthood and Behavioral Problems among Chinese Emerging Adults: The Mediating Role of Physical Activity and Self- Control

引用

International Journal of Mental Health Promotion 2023年第8期25卷 937-948页

作者： Jin Kuang Jeffrey Jensen Arnett Erle Chen Zsolt Demetrovics fabian Herold Rebecca Y.M.Cheung Daniel L.Hall Michaela Markwart markus Gerber Sebastian Ludyga Arthur f.Kramer Liye Zou Body-Brain-Mind Laboratory School of PsychologyShenzhen UniversityShenzhen518060China Department of Psychology Clark UniversityWorcesterMA 01610USA Shenzhen College of International Education Shenzhen518172China Centre of Excellence in Responsible Gaming University of GibraltarGX111AAGibraltar Institute of Psychology ELTE Eötvös Loránd UniversityBudapest1239Hungary Research Group Degenerative and Chronic Diseases MovementFaculty of Health Sciences BrandenburgUniversity of PotsdamPotsdam14476Germany School of Psychology and Clinical Language Sciences University of ReadingReadingRG1UK Massachusetts General Hospital and Harvard Medical School Boston02115USA Department of Sport Exercise&HealthUniversity of BaselBasel4091Switzerland Center for Cognitive&Brain Health Northeastern UniversityBoston02115USA Beckman Institute University of IllinoisIllinois60001USA

Emerging adulthood(EA)is a critical stage of life to develop and sustain a healthy lifestyle,which is also a time of vulnerability to poor physical and mental health *** this study,we conducted a path analysis(N=1326)to examine associations among four dimensions of EA,levels of regular physical activity(PA),self-control,MPA tendency and irrational *** found:1)higher levels of PA predicted both MPA tendency(β=−0.08,95%CI:−0.11 to−0.06,pf-control;2)Instability(β=0.13,95%CI:0.08 to 0.18,pffects on irrational procrastination and Instability also indirectly predicted irrational procrastination via MPA tendency(β=0.03,95%CI:0.02 to 0.05,pfindings proved that perceived features of EA are linked to behavioral problems and supported that regular PA plays a crucial role to protect mental health.

关键词： Emerging adulthood Chinese culture physical activity mobile phone addiction irrational procrastination self-control

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

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：