检索结果-南通市图书馆

Thermal bleaching of optical absorption and photoluminescence spectra of γ-irradiated CaF_2:Dy:Pb:Na single crystals

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2010年第4期28卷 493-497页

作者： s.m. moses.kennedy Department of Physics S.S.N. College of Engineering Rajiv Gandhi Salai Kalavakkam-603 110 Chennai Tamil Nadu India

The variation of the optical absorption (OA) and photoluminescence (PL) spectra with temperature was studied on γ-irradiated CaF2:Dy:Pb:Na single crystals. The OA spectrum showed bands around 2.05, 3.20, 3.82 and 6.20 eV which could be attributed to different sodium associated (sA) colour centres (CCs) such as.m.a and RA+ . Heating the crystal indicated the annihilation and formation of different sACCs. The excitation spectrum for the characteristic Dy3+ emission at 2.14 eV immediately after irradiation was...

关键词： calcium fluoride optical absorption photoluminescence colour centres dysprosium lead sodium rare earths

Genetic analyses of ancient tea trees provide insights into the breeding history and diss.m.nation of Chinese Ass.m.tea(Camellia sinensis ***)

在线全文

学校读者我要写书评

暂无评论

Plant Diversity 2024年第2期46卷 229-237页

作者： miao-miao Li muditha K.meegahakumbura moses C.Wambulwa Kevin s.Burgess.m.chael möller Zong-Fang shen De-Zhu Li Lian-ming Gao CAs Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of BotanyChinese Academy of ScienceKunming650201China Germplasm Bank of Wild species Kunming Institute of BotanyChinese Academy of ScienceKunming650201China Kunming College of Life science University of Chinese Academy of SciencesKunming650201YunnanChina Department of Export Agriculture Faculty of Animal Science and Export AgricultureUva Wellassa UniversityBadulla90000Sri Lanka Department of Life sciences School of Science and ComputingSouth Eastern Kenya University170-90200KituiKenya Department of Biology Columbus State UniversityUniversity System of GeorgiaColumbusGA31907-5645USA Royal Botanic Garden Edinburgh 20A Inverleith RowEdinburghEH35LRScotlandUK Lijiang Forest Biodiversity National Observation and Research station Kunming Institute of BotanyChinese Academy of SciencesLijiang674100YunnanChina

Chinese Ass.m.tea(Camellia sinensis ***)is an important tea crop with a long history of cultivation in Yunnan,*** its potential value as a genetic resource,its genetic diversity and domestication/breeding history remain *** address this issue,we genotyped 469 ancient tea plant trees representing 26 *** *** populations,plus two of its wild relatives(six and three populations of *** and ***,respectively)using 16 nuclear microsatellite *** showed that Chinese Ass.m.tea has a relatively high,but comparatively lower gene diversity(H_(s)=0.638)than the wild relative ***(H_s=0.658).Clustering in sTRUCTURE indicated that Chinese Ass.m.tea and its two wild relatives formed distinct genetic groups,with considerable interspecific *** Chinese Ass.m.tea accessions clustered into three gene pools,corresponding well with their geographic ***,New Hybrids analysis indicated that 68.48%of ancient Chinese Ass.m.tea plants from Xishuangbanna were genetic intermediates between the Puer and Lincang gene *** addition,10%of the ancient Chinese Ass.m.tea individuals were found to be hybrids between Chinese Ass.m.tea and *** results suggest that Chinese Ass.m.tea was domesticated separately in three gene pools(Puer,Lincang and Xishuangbanna)in the mekong River valley and that the hybrids were subsequently selected during the domestication *** the domestication history of Chinese Ass.m.tea in southwestern Yunnan remains complex,our results will help to identify valuable genetic resources that may be useful in future tea breeding programs.

关键词： Tea plant Hybrid origin Genetic diversity Domestication history Camellia sinensis var.ass.m.ca Camellia taliensis

Engineering of efficient visible light photocatalysts:Ti_(1-x+y)Cu_(x)La_(y)O_(2)(x=0.03;y=0,0.005,0.01) compositions

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第3期42卷 497-505,I0003页

作者： s.m.Yakout A.m.Youssef Inorganic Chemistry Department National Research Centre(NRC)El Buhouth StDokkiCairo12622Egypt

In dye-photocatalysis, widening the wavelengths absorption range of catalysts as well as aborting the recombination of the photoexcited charge carriers(electrons-holes pairs) are of paramount *** the current study, we report the photocatalytic characteristics of four compositions composed of TiO_(2),Ti_(0.97)Cu_(0.03)O_(2), Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)powders for two harmful dyes(Congo red and methylene blue). The X-ray diffraction technique verified the configuration of mixed anatase and rutile phases in pure TiO_(2)and Ti_(0.97)Cu_(0.03)O_(2)powders while Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)powders possess anatase phase only. The changes of the band gap structure and dimensions of the unit cell volume of TiO_(2)confirm the substitution of Ti^(4+)sites by Cu^(2+)and La^(3+)ions. Remarkable widening of wavelengths absorption with formation of long absorption tails were found in TiO_(2)(3.13 e V) through insertion of La^(3+)plus Cu^(2+)ions. Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)s.m.les exhibit a visible light band gap of 2.3 and 2.7 e V, respectively. Based on s.m.images, incorporation of Cu^(2+)and La^(3+)ions influences the surface morphology of TiO_(2). The resulting Ti_(0.97)Cu_(0.03)O_(2), Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)powders present enhanced photocatalytic activity towards Congo red dye degradation compared to pure one under natural solar spectrum. The best Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)catalyst exhibits superior photocatalytic activity of 96% for 10 ppm CR dye in 20 min as well as above average photocatalytic efficiency of 63% for 30 ppm CR dye in 120 min. As well, it showed acceptable photodegradation activity of 52% for 30 ppm mB solution in 140 min of sunlight irradiation. The heightened photodegradation efficiency of Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)catalyst can be clarified in terms of higher ch

关键词： s.m.conductor TiO_(2) Rare earths Congo red methylene blue solar spectrum Photodegradation

Effect of radiative loss.m.chanisms on FIR thermometric parameters of Nd^(3+)-doped lithium tellurite glasses

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第7期42卷 1250-1257,I0002页

作者： C.Y.morassuti A.P.L silva L.A.O.Nunes s.m.Lima L.H.C.Andrade Optical and Photothermal spectroscopy Group(GEOF) Center for Studies in Natural Resources(CERNA)State University of Mato Grosso do Sul(UEMS)C.P.351DouradosMSBrazil Renato Archer Information Technology Center Dom Pedro I Highway(SP-65)Km 1436-Chácaras Campos dos AmaraisCampinasSPBrazil Institute of Physics of são Carlos University of São PauloSão CarlosSPBrazil

Nd^(3+)-doped tellurite glasses are promising materials for thermometers based on the fluorescence intensity ratio(FIR)***,at high Nd^(3+)concentrations,energy transfer(ET)processes such as optical reabsorption and cross-relaxation can affect the Nd^(3+)emission,which has been little explored in the ***,the present work investigated the use of Nd^(3+)-doped tellurite glass(s.m.les doped with Nd^(3+)at 0.2 mol%,0.5 mol%,2.0 mol%,and 4.0 mol%)in fluorescence thermometers,in the temperature range from 299 to 371 *** results indicate a strong dependence of the FIR parameters on the Nd^(3+)concentration,due to changes in the emission band profiles caused by optical reabsorption of the Nd^(3+)emissions and cross-relaxation processes.A decrease of the relative sensitivity of the ratio^(4)F_(5/2)→^(4)I_(9/2)/^(4)F_(3/2)→^(4)I_(9/2)is observed for s.m.les doped with higher amounts of Nd^(3+).The maximum relative sensitivity at 299 K is 3.00%/K,which is the highest value among the reported Nd^(3+)ions.

关键词： Nd^(3+)-doped tellurite glass Fluorescence intensity ratio Optical thermometry Judd-Ofelt Rare earths

^(4)He monolayer on graphene:a quantum monte Carlo study

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第9期76卷 149-157页

作者： s Yu m Boninsegni Department of Physics University of AlbertaEdmontonAlbertaT6G 2H5Canada

We revisit the problem of adsorption of a single^(4)He layer on graphene,focusing on the commensurate(C_(1/3))crystalline phase,specifically on whether it may possess a nonzero superfluid response,and on the existence of superfluid phases,either(metastable)liquid or vacancy-doped *** make use of canonical quantum monte Carlo s.m.lations at zero and finite temperature,based on a realistic microscopic model of the *** results confirm the absence of any superfluid response in the commensurate crystal,and that no thermodynamically stable uniform phase exists at lower *** evidence of a possibly long-lived,metastable superfluid phase at C_(1/3)coverage is ***,the results of ground-state projection methods and finite-temperature s.m.lations are entirely consistent.

关键词： superfluidity low-dimensional systems quantum monte Carlo helium supersolids

Direct microwave leaching conditions of rare earth elements in fluorescent wastes

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第6期42卷 1165-1174,I0007页

作者： A.Bilen B.Birol m.N.saridede s.s.Kaplan m.s.sonmez Department of metallurgical and materials Engineering Yildiz Technical UniversityIstanbulTurkey Department of Chemical Engineering and materials science Stevens Institute of TechnologyNew JereyUSA Department of metallurgical and materials Engineering Istanbul Technical UniversityIstanbulTurkey

The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s *** can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth *** the present study,microwave leaching process was conducted to dissolve rare earth elements yttrium(Y),europium(Eu),and remaining rare earth elements(REEs)present in the phosphor powder of the fluorescent *** the yields were *** the microwave leaching process,the effects of the temperature(80-160℃),acid type(hydrochloric acid(HCl),nitric acid(HNO_(3)),sulphuric acid(H_(2)sO_(4))),acid concentration(0.5-6 mol/L),solid to liquid ratio(0.1:10-0.5:10)and reaction time(5-90 min)parameters on leaching efficiencies of varying rare earth elements and calcium were *** highest yield was obtained in the direct microwave leaching of fluorescent waste with the experimental conditions of 6 mol/L HCl,160℃,0.1:10 solid-to-liquid ratio(s:L),and 90 *** energy calculations were made,and kinetic models of the reactions were obtained,and it is observed that Y and Eu dissolution is diffusion-controlled,on the other hand,lanthanum(La),cerium(Ce),and terbium(Tb)were examined to be chemical reaction ***,calcium(Ca)and gadolinium(Gd)seem coherent with the mixed ***,mathematical models of all experimental studies are created with the response surface Box-Behnken method and the correlation coefficients of all the models are over 90%.

关键词： Rare earth elements(REEs) Direct microwave leaching Fluorescent waste Kinetic models Response surface method

Parametric investigation on the novel and cost-effective nano fly ash impregnated geopolymer system for sustainable construction

在线全文

学校读者我要写书评

暂无评论

Frontiers of structural and Civil Engineering 2024年第2期18卷 170-183页

作者： R.mOHANA s.m.Leela BHARATHI Department of Civil Engineering Mepco Schlenk Engineering CollegeSivakasi 626123India

The hazardous environmental effects of greenhouse gas emissions and climate change demand alternative sources for cementitious.m.terials in the construction *** development of geopolymer structures provides a way of producing 100%cement-free *** this research work,a novel and s.m.le way of deriving nano particles from waste fly ash particles is *** effect of adding the synthesized nano fly ash particles as a filler medium in geopolymer mortars was investigated by considering strength and durability *** optimization was done by using regression analysis on the geopolymer mortar and the impact of adding nano fly ash particles was studied by varying different percentages of addition ranging from 0 to 7.5%by weight of binder *** the results,it was observed that 1%nano fly ash acted not only as a filler but also as nano-sized precursors of the polymerization process,resulting in denser geopolymer *** can explain the extraordinary gain in strength of 72.11 mPa as well as the denser core with negligible level of chloride ion penetration,making the material suitable for the development of structures susceptible to marine environment.

关键词： geopolymer nano fly ash chloride ion penetration durability polymerization fillers

QCD s.m.rule study of J^(P)=1^(±)exotic states with two heavy quarks in the molecular picture

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

Chinese Physics C 2024年第6期48卷 31-37页

作者： T.m.Aliev s.Bilmis.m.savcı Department of Physics Middle East Technical UniversityAnkara06800Turkey TUBITAK ULAKBIm Ankara06510Turkey

In this study,the spectroscopic parameters of exotic molecular states composed of mesons containing two heavy quarks(scalar-axial and pseudoscalar-axial meson combinations)are investigated within the QCD s.m.*** findings reveal that molecular states containing charm quarks do not form bound states,whereas states with b-quarks can form exotic molecular *** observation has significant implications for understanding the structure of these exotic states.

关键词： QCD s.m.rules exotic mesons molecular states

Analysis of strong decays of sU(3)partners ofΩ(2012)baryon

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第8期48卷 34-41页

作者： T.m.Aliev s.Bilmis.m.savci Department of Physics Middle East Technical UniversityAnkara 06800Turkey TUBITAK ULAKBIm Ankara 06510Turkey

We estimate the coupling constants and decay widths of the sU(3)partners of theΩ(2012)hyperon,as discovered by the BELLE Collaboration,using the distribution amplitudes of the octet baryons within the light cone s.m.rules *** study includes a comparison of the obtained results for the relevant decay widths with those derived within the framework of the flavor sU(3)*** observe a good agreement between the predictions of both ***,our result on the decay width ofΩ→ΞK is compatible with the existing experimental result within the uncertainties of the model *** results can provide helpful insights for determining the nature of the sU(3)partners of theΩ(2012)baryon.

关键词： coupling constants light cone s.m.rule hyperon