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Spectroscopic investigations on Yb^3+ doped and Pr^3+/Yb^3+ codoped tellurite glasses for photonic applications

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Journal of Rare Earths 2021年第1期39卷 33-42,I0002页

作者： M.Seshadri M.J.v.Bell v.Anjos Y.Messaddeq Grupo de Engenharia e Espectroscopia de Materiais Departamento de Fisica-ICEUniversidade Federal de Juiz de ForaJuiz de ForaMG36036-900Brazil Centre d'Optique Photonique et Laser2375 Rue de la TerrasseUniversite LavalQuebecQCG1V 0A6Canada

In this work we repo rt on structural and spect roscopic properties of Yb^3+doped and Pr^3+/Yb^3+co-doped TeO2-Bi2 O3-ZnO-Li2 O-Nb2 O5(TBZLN)tellurite *** and stretching modes of TeO2 and Te-OH bond(strong and weak)were analysed from the deconvolution of observed Raman and FT-IR *** on the absorption measurements,the energy bands of Yb^3+and Pr^3+ions are *** spectroscopic properties for the radiative transitions of Yb^3+and Pr^3+ions were reported using McCumber and Judd-Ofelt *** emission bands originating from 3 P1 and 3 P0 to lower lying levels of Pr^3+were registered under 447 nm *** emission band around 1334 nm assigned to the Pr3:1 G4→3 H5 was observed when excited at 980 *** stimulated emission cross-section(σemi(λ))and effective linewidth(Δλeff)for the 3 P1→3 H6,3 P1→3 H5,3 P0→3 H6,3 P0→3 F2,3 P1→3 F3,3 P1→3 F4,3 P0→3 F4 and 1 G4→3 H5 transitions of Pr^3+are *** luminescence in Pr^3+/Yb^3+codoped glass upon 980 nm excitation was *** resonant transfer processes between Yb^3+and Pr^3+ions are presented and *** chromaticity co-ordinates were also evaluated from the visible emission spectra showing that Pr^3+/Yb^3+co-doped glass may be suitable for the development of yellow-orange(λexc=447 nm)and near white light(λexc=980 nm)emitting devices in photonics.

关键词： Rare earth ions Tellurite glass Spectroscopic properties Upconversion luminescence

Segments of spiral arms of the Galaxy traced by classical Cepheids:effects of age heterogeneity

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Research in Astronomy and Astrophysics 2020年第12期20卷 357-366页

作者： Angelina v.veselova Igor’I.Nikiforov Department of Celestial Mechanics Saint Petersburg State UniversityUniversitetskij Prospekt 28Staryj PeterhofSaint Petersburg198504 Russia

We investigated the dependence of the parameters of the segments of spiral arms of the Galaxy on the age of classical *** catalog of Cepheids(Mel’nik et al.)was divided into two samples—relatively young(P>9d)and relatively old(Peters of the spiral structure were determined both for two samples separately and jointly for the combination of two systems of segments traced by young and old *** most of the segments,their parameters for young and old objects differ *** into account the difference between the two segment systems,we obtained the estimate R0 equal to 7.23^+0.19/-0.18 kpc,which in the modern Large Magellanic Cloud(LMC)calibration corresponds to the value of R0=8.08^+0.2/-10.20|stat.^+0.38/-0.36|*** is shown that the displacement between the segments is not reduced to the effect of differential rotation *** interpret this displacement for objects of Perseus and Sagittarius-2 segments,we carried out a dynamic modeling of the change in the position of the segment points when moving in the smooth gravitational field of the *** the angular velocity of rotation of the spiral pattern Ωp=25.2±0.5 km s 1 kpc 1(Dambis et al.)the observed displacement between segments on young and old objects can be explained by the amplitude of spiral perturbations of the radial velocity of u=10±1.5 km s *** the constructed double system of spiral segments,it is demonstrated that the assumption of constancy of the pitch angles within each segment and the assumption that the pole of the spiral pattern is in the direction of the nominal center of the Galaxy do not contradict the data within the range of uncertainty.

关键词： Galaxy:fundamental parameters Galaxy:structure

The kinematical and space structures of IC 2391 open cluster and moving group with Gaia-DR2

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Research in Astronomy and Astrophysics 2020年第2期20卷 21-30页

作者： E.S.Postnikova W.H.Elsanhoury Devesh P.Sariya N.v.Chupina S.v.vereshchagin Ing-Guey Jiang Institute of Astronomy of Russian Academy of Sciences(INASAN) 48 Pyatnitskaya st.MoscowRussia Astronomy Department National Research Institute of Astronomy and Geophysics(NRIAG)11421HelwanCairoEgypt(Affiliation ID:60030681) Physics Department Faculty of Science and ArtsNorthern Border UniversityTuraif BranchSaudi Arabia Department of Physics and Institute of Astronomy “National Tsing Hua University”Hsinchu 30013

The kinematical parameters,spatial shape and structure of the open cluster IC 2391 and the associated stellar stream are studied here using Gaia Data Release 2(GDR2) astrometry *** apex positions are determined for the open cluster IC 2391(data taken from Cantat-Gaudin et al.) and for the kinematical stream’s stars mentioned in Montes et *** both convergent point and AD-diagram *** values of apex coordinates are:(A,D)CP=(6.~h17 ± 0.~h004,-6.°88 ± 0.°381;for cluster) and(6.~h07 ± 0.~h007,-5.°00 ± 0.°447;stream),and(A0,D0) =(6.~h12 ± 0.~h004,-3.°4 ± 0.°3;cluster) and(6.~h21 ±0.~h007,-11.°895 ± 0.°290;stream).The results are in good agreement with the previously calculated *** positions of the stars in the disk and the spatial dispersion velocities are *** paths of cluster and associated stream are traced in the disk by orbit calculation back in time to their places of formation.A possible genetic relationship between the cluster and stream has been *** approximation of the spatial and kinematical shape of the stream and the cluster is *** to this study,even though currently the cluster and stream seem to have a spatial difference in their locations,they appear to have formed in the same region of the Galactic disk.

关键词： Stars:kinematics and dynamics Galaxy:stellar content (Galaxy:)open clusters and associations:individual:IC 2391

Down-and up-conversion processes in Nd^(3+)/Yb^(3+)co-doped sodium calcium silicate glasses with concomitant Yb^(2+)assessment

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Journal of Rare Earths 2023年第3期41卷 342-348,I0001页

作者： R.F.Muniz v.S.Zanuto M.S.Gibin J.v.Gunha A.Novatski J.H.Rohling A.N.Medina M.L.Baesso Departament of Science State University of MaringáAv.Reitor Zeferino Vaz s/nGoioerê87360-000PRBrazil Departament of Physics State University of MaringáAv.Colombo 5790Maringá87020-900PRBrazil Departament of Physics State University of Ponta GrossaAv.Carlos Cavalcanti4748Ponta Grossa 84030-900PRBrazil

Novel Nd^(3+)/Yb^(3+)co-doped sodium calcium silicate glasses were prepared by melting quenching method:Spectroscopic study was carried out as a function of doping content by fixing sensitizer(Nd^(3+))concentration to 0.2 mol%and adjusting activator(Yb^(3+))from 0 to 1.0 mol%.The energy transfer(et)mechanisms between Nd^(3+)and Yb^(3+)are discussed based on their energy levels and excitation powerdependence emission *** show that the presence of Yb^(2+)might be considered for the Nd^(3+)-free and co-doped *** et was confirmed by the down-conversion NIR emission spectra of the doped and co-doped samples under excitation at 808 *** mechanisms observed seem to involve only one vIS absorbed photon for each NIR emitted via direct energy transfer between^(4)F_(3/2)of Nd^(2+)and^(2)F_(5/2)of Yb^(3+)compensated by phonon assistance due to energy gap between these *** efficiency of et increases with the ytterbium content up to almost 90%for the sample with 1 mol%of Yb2O3,which was evaluated by lifetime ***-conversion photoluminescence by exciting trivalent ions of neodymium(808 nm)and ytterbium(975 nm)is *** observed up-converted emission bands are related to the 4f-4f transitions of Nd^(3+)and the spin-forbidden 5d-4f transition of Yb^(2+).Nd^(3+)upconversion emission is observed under 975 nm excitation,presenting an almost quadratic emission dependence with power excitation,which suggests that two laser photons participate in the up-conversion(UC)process,showing that et occurs by a phonon-assisted energy transfer and cooperative energy transfer.

关键词： Solar cells Energy transfer Glassy systems Rare earths

Monte Carlo study of nanowire magnetic properties

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Chinese Physics B 2013年第5期22卷 514-518页

作者： R. Masrour L. Bahmad A. Benyoussef Laboratoire de Magnétisme et Physique des Hautes Energies URAC 12Université Mohammed V-AgdalFaculté des Sciences Laboratory of Materials ProcessEnvironment and QualityCady Ayyad UniversityNational School of Applied Sciences

In this work, we use Monte Carlo simulations to study the magnetic properties of a nanowire system based on a honeycomb lattice, in the absence as well as in the presence of both an external magnetic field and crystal field. The system is formed with NL layers having spins that can take the values σ= ± 1/2 and S =±1,0. The blocking temperature is deduced, for each spin configuration, depending on the crystal field A. The effect of the exchange interaction coupling Jp between the spin configurations σ and S is studied for different values of temperature at fixed crystal field. The established ground-state phase diagram, in the plane （Jp, △）, shows that the only stable configurations are：（1/2,0）, （1/2, ＋1）, and （1/2,- 1）. The thermal magnetization and susceptibility are investigated for the two spin configurations, in the absence as well as in the presence of a crystal field. Finally, we establish the hysteresis cycle for different temperature values, showing that there is almost no remaining magnetization in the absence of the external magnetic field, and that the studied system exhibits a super-paramagnetic behavior.

关键词： Monte Carlo simulations nanowire magnetic field crystal field

Modelling reference evapotranspiration using gene expression programming and artificial neural network at Pantnagar,India

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Information Processing in Agriculture 2023年第4期10卷 547-563页

作者： Pangam Heramb Pramod Kumar Singh K.v.Ramana Rao A.Subeesh Division of Irrigation and Drainage Engineering ICAR-Central Institute of Agricultural EngineeringBhopal 462038India Department of Irrigation and Drainage Engineering G.B.Pant University of Agriculture and TechnologyPantnagar 263145India Division of Agricultural Mechanization ICAR-Central Institute of Agricultural EngineeringBhopal 462038India

Evapotranspiration is an essential component of the hydrological cycle that is of particular interest for water resource *** quantification is helpful in irrigation scheduling,water balance studies,water allocation,*** of reference evapotranspiration(et0)using both gene expression programming(GEP)and artificial neural network(ANN)techniques was done using the daily meteorological data of the Pantnagar region,India,from 2010 to 2019.A total of 15 combinations of inputs were used in developing the et0 *** model with the least number of inputs consisted of maximum and minimum air temperatures,whereas the model with the highest number of inputs consisted of maximum air temperature,minimum air temperature,mean relative humidity,number of sunshine hours,wind speed at 2mheight and extra-terrestrial radiation as inputs and with et0 as the output for all the *** the GEP models were developed for a single functional set and pre-defined genetic operator values,while the best structure in each ANN model was found based on the performance during the testing *** was found that ANN models were superior to GEP models for the estimation *** was evident from the reduction in RMSE values ranging from 2%to 56%during training and testing phases in all the ANN models compared with GEP *** ANN models showed an increase of about 0.96%to 9.72%of R2 value compared to the respective GEP *** comparative study of these models with multiple linear regression(MLR)depicted that the ANN and GEP models were superior to MLR models.

关键词： Artificial Neural Networks Evolutionary algorithms Gene Expression Programming Machine Learning Regression Analysis Reference evapotranspiration models

Can glucagon-like peptide-1(GLP-1) analogues make neuroprotection a reality?

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Neural Regeneration Research 2020年第10期15卷 1852-1853页

作者： Maryna v.Basalay Sean M.davidson Derek M.Yellon The Hatter Cardiovascular Institute University College London

Currently,ischemic stroke remains one of the most costly and devastating clinical syndromes,accounting for 9%of all deaths and being the second leading cause of death in the world(davidson et al.,2018).Approximately 20%of strokes are caused by intracerebral hemorrhage,while the other^80%are classified as *** the discovery of thrombolysis,reperfusion therapy became an option for the treatment of ischemic *** recently,endovascular recanalization with mechanical thrombectomy has brought about a paradigm shift in the optimal management of patients with large vessel ***,early reperfusion is the only therapy that is proven to limit infarct size in patients with acute ischemic ***,despite a successful recanalization being achieved in more than 70% of patients treated with mechanical thrombectomy+/–intravenous tissue recombinant plasminogen activator,functional independence(modified Rankin score 0–2 at 3 months after ischemic stroke)is obtained only in^45% of *** reveals the further need to develop new adjunctive neuroprotective treatment strategies alongside reperfusion therapy.

关键词： protective treatment independence

最大无氧功率、速度和力与无氧能力的关系探讨

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体育科学 1992年第2期13卷 54-56,95页

作者：谢克刚南京师范大学体育系南京210024

实验对象为接受专业和业余训练的运动员68名(男),采用MONARK868功率自行车作为测试仪器,以vandewall(1987年)建立的F—v方法测定最大功率。实验结果表明,受试者力(P_o),速度(v_o)值的大小及其组合模式与他们所具有的无氧能力强弱和他们... 详细信息

实验对象为接受专业和业余训练的运动员68名(男),采用MONARK868功率自行车作为测试仪器,以vandewall(1987年)建立的F—v方法测定最大功率。实验结果表明,受试者力(P_o),速度(v_o)值的大小及其组合模式与他们所具有的无氧能力强弱和他们从事的项目有关。同时也提示,利用F—v测试方法提供的P_o,v_o值信息可以在一定程度上分析评定不同对象的无氧能力。

关键词：最大无氧功率(Wmax) 速度(v_o) 力(P_o) 无氧能力

Partial Beclin 1 silencing aggravates doxorubicin-and Fasinduced apoptosis in HepG2 cells

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World Journal of Gastroenterology 2006年第18期12卷 2895-2900页

作者： Fanny Daniel Agnès Legrand Dominique Pessayre Nathalie vadrot véronique Descatoire Dominique Bernuau Institut National de la Santé et de la Recherche Médicale INSERMU773Centre de Recherche Bichat Beaujon CRB3BP 416F-75018ParisFrance Université paris 7 Denis Diderot site BichatBP 416F-75018ParisFrance

AIM： To investigate the role of Beclin 1 on the susceptibility of HepG2 cells to undergo apoptosis after anti-Fas antibody or doxorubicin treatment. MetHODS： Beclin 1 silencing was achieved using RNA interference. DNA ploidy, the percentage of apoptotic cells and the mitochondrial membrane potential were assessed by flow cytometry. Levels of Beclin 1, BCI-XL and cytochrome c, and the cleavage of poly （ADP-ribose） polymerase （PARP） were assayed by using Western blots. RESULTS： Beclin 1 expression decreased by 75% 72 h after Beclin 1 siRNA transfection. Partial Beclin 1 silencing significantly increased the percentage of subG1 cells 24 and 40 h after treatment with doxorubicin or anti-Fas antibody, respectively, and this potentiation was abrogated by treatment with a pan-caspase inhibitor. Partial Beclin 1 silencing also increased PARP cleavage, mitochondrial membrane depolarization and cytosolic cytochrome c. The pro-apoptotic consequences of partial Beclin 1 silencing were not associated with a decline in Bcl-XL expression.CONCLUSION： Partial Beclin 1 silencing aggravates mitochondrial permeabilization and apoptosis in HepG2 cells treated with an anti-Fas antibody or with doxorubicin.

关键词： Beclin 1 Apoptosis HepG2 cells Anti-Fas antibody Doxorubicin