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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

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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

Disjointed Equivalence of Gravitational and Inertial Mass

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Journal of Modern Physics 2023年第3期14卷 237-270页

作者： Dirk J. pons Department of Mechanical Engineering University of Canterbury Christchurch New Zealand

Problem—Contemporary physics offers no underlying reason for the equivalence of inertial and gravitational mass. Approach—The equivalence is examined from the new physics provided by the cordus theory, being a non-local hidden-variable (NLHV) theory. Mathematical formalisms are derived for masses and observers in different fabric densities. Findings—A disjointed equivalence is predicted, whereby inertial and gravitational masses are equivalent in any one situation, but a different equivalence holds when the fabric densities change. Consequently this theory predicts that the gravitational constant G varies with fabric density, and hence would be different across the universe and across time. Not only is the gravitational constant non-constant, but the formulation of gravitation changes with fabric density. Specifically, the theory predicts gravity is stronger at genesis (and the end of the universe) such that orbit velocity vB ∝ (where rB is orbit radius), compared to weaker gravitation at middle life epochs with rB ∝ . The current Earth location and epoch correspond to the latter case, i.e. Newtonian gravitation is recovered. The findings disfavour the existence of both dark energy and dark matter, and instead attribute these effects to differences in the fabric density. Originality—The work makes the contribution of deriving a mass equivalence relationship that includes fabric density, identifying a disjointed mass equivalence, and showing that the gravitation formulation itself changes with relative fabric densities.

关键词： Identity of Mass Gravitation Inertia General Relativity Quantum Mechanics

Temporal No-Linearity: An Alternative to Dark Energy

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Journal of Modern Physics 2022年第4期13卷 323-335页

作者： Bartolomé pons-Rullán University of the Balearic Islands Palma de Mallorca Spain

Mathematical compatibilities and constraints of a hypothetical 5D space-time with time referenced by two coordinates (3-2) have been revisited in detail in several recent papers. It has been prescribed from the GR the compatibility constraints of the FLRW metric in each temporal brane, to be restricted to Closed Universes, Smooth Initial Singularities, and “Open CTC”. In a first view, this leads to leaving these works considering mathematical games discarded by the Standard Candles data. However, if time would be referred by two coordinates, they would not be linearly related, and it will be mathematically stated that space-time may not be flat in any case because time-like branes geometry will never be. If so, the time scale “lived” over a two-time dimension geodesic necessarily is not constant over its linear projection on one of both coordinates. Consequently, the correlations between Redshift and Distance Modulus—Distance Ladder—may be corrected by a synchronization function (if a no-linear two-time geodesic trajectory over a “warped temporal geometry” is linearly divided into constant segments, then their projections are not linear in any case). We apply an example of time-trajectory over the time slices, matching the Standard Candle data for a Closed Universe dominated by matter (>90%) in a bulk 3-2 configuration, with open temporal branes and smooth singularity. If time can be referred by two coordinates, then there is no need of Darkness to explain astrophysical data and Universe can be closed.

关键词： Closed Universe Multidimensionality Time-Like Dimensions No-Linear Time Accelerated Expansion Smooth Big Bang

Building the World Wide Hypermap(WWH)with a RESTful architecture

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International Journal of Digital Earth 2014年第3期7卷 175-193页

作者： Joan Maso Xavier pons Alaitz Zabala Center for Ecological Research and Forestry Applications(CREAF) Universitat Autònoma de BarcelonaBarcelonaSpain Department of Geography Universitat Autònoma de BarcelonaBarcelonaSpain

The hypermap concept was introduced in 1992 as a way to hyperlink geospatial features to text,multimedia or other geospatial *** then,the concept has been used in several applications,although it has been found to have some *** the other hand,Spatial Data Infrastructures(SDIs)adopt diverse and heterogeneous service oriented architectures(SOAs).They are developed by different standard bodies and are generally disconnected from mass market web *** work expands the hypermap concept to overcome its limitations and harmonise it with geospatial resource oriented architecture(ROA),connecting it to the semantic web and generalising it to the World Wide Hypermap(WWH)as a tool for building a single‘Digital Earth’.Global identifiers,dynamic links,link purposes and resource management capabilities are introduced as a solution that orchestrates data,metadata and data access services in a homogeneous *** is achieved by providing a set of rules using the current Internet paradigm formalised in the REpresentational State Transfer(REST)architecture and combining it with existing Open Geospatial Consortium(OGC)and International Organization for Standardization(ISO)standards.A reference implementation is also presented and the strategies needed to implement the WWH,which mainly consist in a set of additions to current Geographic Information System(GIS)products and a RESTful server that mediates between the Internet and the local GIS applications.

关键词： SDI URI standards hypermap RESTful

Developing spatially and thematically detailed backdated maps for land cover studies

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International Journal of Digital Earth 2017年第2期10卷 175-206页

作者： Juan JoséVidal-Macua Alaitz Zabala Miquel Ninyerola Xavier pons Dep Geografia Grumets Research GroupUniversitat Autònoma de BarcelonaBellaterraCataloniaSpain Dep Biologia Animal Vegetal i EcologiaGrumets Research GroupUniversitat Autònoma de BarcelonaBellaterraCataloniaSpain

Global or regional land cover change on a decadal time scale can be studied at a high level of detail using the availability of remote sensing data such as that provided by ***,there are three main technical challenges in this ***,the generation of land cover maps without reference data is problematic(backdating).Second,it is important to maintain high accuracies in land cover change map products,requiring a reasonably rich legend within each ***,a high level of automation is necessary to aid the management of large volumes of *** paper describes a robust methodology for processing time series of satellite data over large spatial *** methodology includes a retrospective analysis used for the generation of training and test data for historical periods lacking reference *** methodology was developed in the context of research on global change in the Iberian *** this study we selected two scenes covering geographic regions that are representative of the Iberian *** each scene,we present the results of two classifications(1985-1989 and 2000-2004 quinquennia),each with a legend of 13 *** overall accuracy of over 92%was obtained for all 4 maps.

关键词： Land cover mapping Landsat statistical classifiers backdating Iberian Peninsula

Visual and ocular effects from the use of flat-panel displays

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International Journal of Ophthalmology(English edition) 2016年第6期9卷 881-885页

作者： Esteban Porcar Alvaro M.pons Amalia Lorente Department of Optics Optometry and Vision Science UnitPhysics CollegeUniversity of ValenciaBux~assotValencia 46100Spain Department of OpticsⅡ Optometry CollegeComplutense University of MadridMadrid 28040Spain

AIM： To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit （VDU） users with flat-panel displays. METHODS： One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a VDU. RESULTS： Seventy-two percent of participants reported eye symptoms related to VDU use. Eye symptoms from moderate-to-severe were found in 23% of participants. The main symptom was moderate-to- severe tired eyes （14%）; followed by sensitivity to bright lights （12%）, blurred vision at far distances （10%）, eyestrain or dry eye or irritated or burning eyes （9%）, difficulty in refocusing from one distance to another or headache （8%） and blurred vision at near or intermediate distances （〈4%）. Eye symptoms were greater among females （P=0.005） and increased with VDU use, markedly above 6h spent using a VDU in a typical day （P=0.01）. CONCLUSION： Significant eye symptoms relate to VDU use often occur and should not be underestimated. The increasing use of electronic devices with flat-panel display should prompt users to take appropriate measures to prevent or to relieve the eye symptoms arising from their use.

关键词： asthenopia eye symptoms computerterminals computer vision syndrome

LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals

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Nano Research 2021年第3期14卷 797-806页

作者： Frederike Carl Leonie Birk Bettina Grauel Monica.pons Christian Würth Ute Resch-Genger Markus Haase Institute of Chemistry of New Materials Department Biology/ChemistryUniversity OsnabrueckBarbarastr.749076OsnabrueckGermany Division 1.2 Biophotonics Federal Institute for Materials Research and Testing(BAM)Richard-Willstaetter-Str.1112489BerlinGermany

We developed a procedure to prepare luminescent LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF_(4):Yb(Yb:YLF)and LiYF_(4):Yb,Er(Yb,Er:YLF)with identical doping *** the luminescence decay times of Yb^(3+)and Er^(3+)are known to be very sensitive to the presence of quenchers,the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell *** improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based ***,the shell was prepared via a newly developed method characterized by a very low nucleation rate for particles of pure LiYF_(4) shell ***,anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH−in the crystal lattice,known to quench the emission of Yb^(3+)*** power density(P)-dependent absolute measurements of the upconversion luminescence quantum yield(ΦUC)of LiYF_(4):Yb,Er/LiYF_(4) core/shell particles reveal a maximum value of 1.25%at P of 180 W·cm^(−2).Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes,theseΦUC values are the highest reported so far for LiYF_(4):18%Yb,2%Er/LiYF_(4) nanocrystals without additional *** improvements may nevertheless be possible by optimizing the dopant concentrations in the LiYF_(4) nanocrystals.

关键词： nanocrystal decay time luminescence LiYF_(4) quantum yield upconversion

Ecto-F_1-ATPase: A moonlighting protein complex and an unexpected apoA-I receptor

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World Journal of Gastroenterology 2010年第47期16卷 5925-5935页

作者： Pierre Vantourout Claudia Radojkovic Laeticia Lichtenstein Véronique pons Eric Champagne Laurent O Martinez Institut national de la santé et de la recherche médicale U1048 Institute of Metabolic and Cardiovascular Diseases Université Toulouse III Paul-Sabatier

Mitochondrial ATP synthase has been recently detected at the surface of different cell types, where it is a high affinity receptor for apoA-I, the major protein component in high density lipoproteins (HDL). Cell surface ATP synthase (namely ecto-F1-ATPase) expression is related to different biological effects, such as regulation of HDL uptake by hepatocytes, endothelial cell proliferation or antitumor activity of Vγ9/Vδ2 T lymphocytes. This paper reviews the recently discovered functions and regulations of ecto-F1-ATPase. Particularly, the role of the F1-ATPase pathway(s) in HDL-cholesterol uptake and apoA-Imediated endothelial protection suggests its potential importance in reverse cholesterol transport and its regulation might represent a potential therapeutic target for HDL-related therapy for cardiovascular diseases. Therefore, it is timely for us to better understand how this ecto-enzyme and downstream pathways are regulated and to develop pharmacologic interventions.

关键词： F1Fo ATP synthase High density lipoproteins receptor Apolipoprotein A-I Purinergic receptor P2Y13 Adenylate kinase Nucleotide Endothelium Antitumor immunity

Prevention of late complications with coverage agents in endoscopic resection of colorectal lesions: Current landscape in gastrointestinal endoscopy

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World Journal of Gastroenterology 2021年第15期27卷 1563-1568页

作者： Vicente Lorenzo-Zúñiga Marco Bustamante-Balén Vicente pons-Beltrán Endoscopy Unit Department of GastroenterologyHospital Universitari i Politècnic La FeValencia 46026Spain Digestive Diseases Department La Fe Polytechnic University HospitalValencia 46026Spain

Endoscopic removal of large(≥20 mm)non-pedunculated colorectal lesions(LNPCLs)may result in major adverse events,such as delayed bleeding(DB)and delayed perforation(DP),despite closure of the mucosal defects with *** application of a coverage agent refers to the creation of a shield with a biocompatible medical device(tissue or hydrogel)with proven bioactive *** of the eschar after endoscopic resection provides shielding protection to prevent delayed *** aim of the present review was to systematically collect and review the currently available literature regarding the prevention of DB and DP with coverage agents after endoscopic mucosal resection or endoscopic submucosal dissection of LNPCLs.

关键词： Large colorectal lesions Delayed bleeding Topical application Endoscopic mucosal resection Endoscopic submucosal dissection