Synthesis and optical characterization of europium and samarium doped La2O3-Y2O3

Seskvioksidi kubične biksbitne strukture se često koriste kao matrice za fosfore na baziretkih zemalja. Posebno su važni za proizvodnju luminescentnih transparentnih keramikakoje se koriste za scintilatorske detektore i keramičke lasere. U tim slučajevima, kubičnastruktura i mala veličina čestica sinterovane keramike je krucijalna za postizanjetransparentnosti. Nanokristalinični La2O3−Y2O3 čvrsti rastvori sa visokim sadržajem La2O3su značajni zato što je La2O3 jako sredstvo za sinterovanje. Međutim, nanokristaliničnimaterijali imaju različite termodinamičke i kristalizacione osobine u odnosu naodgovarajuće kompaktne materijale. Stoga nanomaterijali mogu imati različite kristalnestrukture u odnosu na kompaktne materijale čak iako imaju isti hemijski sastav.U ovoj tezi su sintetisani nanostrukturni prahovi na bazi čvrstih rastvora Y2O3 i La2O3((Y1-xLax)2O3 (x = 0, 0,1; 0,2; 0,3; 0,4; 0,5; 1)) metodom polimerno−kompleksnog rastvora.Iako je Y2O3 seskvioksid C-kubičnog tipa, a La2O3 heksagonalne strukture, u slučajunanokristala kubična struktura je dobijena sa sadržajem La2O3 do 50%. Ovo je značajnoviše nego u kompaktnim materijalima iste strukture, gde sadržaj La2O3 ne prelazi 20%. Samaterijalima na bazi lantan-oksida mora da se postupa sa predostrožnošću zbog njegovogafiniteta da reaguje sa atmosferskom vodom formirajući novi stabilan La(OH)3..

Synthesis and optical characterization of europium and samarium doped La2O3-Y2O3

Seskvioksidi kubične biksbitne strukture se često koriste kao matrice za fosfore na baziretkih zemalja. Posebno su važni za proizvodnju luminescentnih transparentnih keramikakoje se koriste za scintilatorske detektore i keramičke lasere. U tim slučajevima, kubičnastruktura i mala veličina čestica sinterovane keramike je krucijalna za postizanjetransparentnosti. Nanokristalinični La2O3−Y2O3 čvrsti rastvori sa visokim sadržajem La2O3su značajni zato što je La2O3 jako sredstvo za sinterovanje. Međutim, nanokristaliničnimaterijali imaju različite termodinamičke i kristalizacione osobine u odnosu naodgovarajuće kompaktne materijale. Stoga nanomaterijali mogu imati različite kristalnestrukture u odnosu na kompaktne materijale čak iako imaju isti hemijski sastav.U ovoj tezi su sintetisani nanostrukturni prahovi na bazi čvrstih rastvora Y2O3 i La2O3((Y1-xLax)2O3 (x = 0, 0,1; 0,2; 0,3; 0,4; 0,5; 1)) metodom polimerno−kompleksnog rastvora.Iako je Y2O3 seskvioksid C-kubičnog tipa, a La2O3 heksagonalne strukture, u slučajunanokristala kubična struktura je dobijena sa sadržajem La2O3 do 50%. Ovo je značajnoviše nego u kompaktnim materijalima iste strukture, gde sadržaj La2O3 ne prelazi 20%. Samaterijalima na bazi lantan-oksida mora da se postupa sa predostrožnošću zbog njegovogafiniteta da reaguje sa atmosferskom vodom formirajući novi stabilan La(OH)3..

Annealing and Doping Concentration Effects on Y2O3: Sm3+ Nanopowder Obtained by Self-Propagation Room Temperature Reaction

In this report, structure, morphology and luminescence of Y2O3:Sm3+ nanoparticles prepared by self-propagating room temperature reaction are presented. This new, simple and cost effective synthesis allows obtaining desired phase composition by mixing appropriate amounts of yttrium and samarium nitrates together with sodium hydroxide. A set of samples is prepared with different Sm3+ concentrations (0.1, 0.2, 0.5, 1 and 2 at %) in order to observe changes of luminescence properties. Also, effects of post synthesis annealing at several temperatures (600 degrees C, 800 degrees C and 1100 degrees C) are analyzed. For all samples X-ray diffraction showed that powders have cubic bixbyite structure (I alpha-3), and TEM analysis showed particles of less than 100 nm. Luminescence emission spectra clearly show peaks characteristic for electronic spin-forbidden transition of Sm3+ ions (4)G(5/2)- GT H-6(5/2), H-6(7/2) and H-6(9/2) centered at 578, 607 and 654 nm, respectively. Emission lifetime values decrease with Sm3+ ion concentration increment, from 1.94 ms for 0.1 at% to 0.97 ms for 2 at%. In addition, enlargement of lifetime value is observed when thermal treatment is done at the highest temperature due to the elimination of luminescence quenching species from the surface of particles

Y3Al5O12:Re3+ (Re=Ce, Eu, and Sm) Nanocrystalline Powders Prepared by Modified Glycine Combustion Method

Yttrium aluminum garnet doped with rare earth ions (Ce3+, Eu3+ and Sm3+) was prepared by modified glycine method. Ce3+ as a dopant was used in four different concentrations (Y3-xCexAl5O12; x(%) = 1, 2, 3, 5), while doping concentration of Eu3+ and Sm3+ was Y3-xEuxAl5O12; x(%) = 3 and Y3-xSmxAl5O12; x(%) = 1, respectively. Phase composition of powders was investigated using XRD technique and expected target phase was confirmed. Photoluminescent characterization included measurements of excitation and emission spectra, as well as determination of emission decays. Y3-xCexAl5O12 shows intense broad-band emission, with maximum in green spectral region, at about 524 nm under ultraviolet or blue excitation. The origin of the luminescence is the 5d(1)- GT 4f(1) transition which is both parity and spin allowed. Ultraviolet and blue excitations of Eu3+ and Sm3+ doped Y3Al5O12 produce intense orange and red emissions. These emissions are phosphorescent in character and come from spin forbidden f-f electron transitions in Eu3+ and Sm3+ ions. For the case of Eu3+ doping emission comes mainly from D-5(0)- GT F-7(1) transitions with Stark components peaking at 590 nm and 590.75 nm, and with emission decay of 4.15 ms. In the case of Sm3+ doping, the emission spectrum, shows (4)G(5/2)- GT H-6(5/2), (4)G(5/2)- GT H-6(7/2), and (4)G(5/2)- GT H-6(9/2) transitions, with the most intense stark components positioned at 567.5 nm, 617 nm, and 650 nm, respectively and for transition centered at 617 nm, emission decay is 3.12 ms

Tims and maldi tof of endohedral 99mTc@C60 metallofullerene

Mass spectral studies (both TIMS – thermal ionization and MALDI TOF – matrixassisted laser desorption time-of-flight mass spectrometry) of the endohedral metallofullerenes, 99mTc@C60 and 99mTc@C70, provided detailed structural and reactivity information about these unusual species. MS experiment revealed that both fullerenes and endohedral metallofullerenes fragment by multiple C2 loss. However, a difference in the terminal fragmentation products was observed for metallofullerene relative to C60, suggesting that the encapsulation metal strongly impacts the fragmentation product. Singly charged cations of the metallofullerenes (M@Cn + ) were completely unreactive in the gas phase with oxygenated compounds such as ethylene oxide: however, the corresponding neutral species appear to react readily with oxygenated species. Collisional dissociation of the ionized endohedral fullerenes listed above revealed multiple C2 loss (either as sequential C2 loss or larger C2n eliminations) to generate similar terminal fragmentation products, which might be predicted due to the similar ionic radii of the encapsulated metals. The observed ionization energies of endohedral molecules were, 5.1 ± 0.1 eV and 5.3 ± 0.1 eV, respectively.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Photoluminescence of the Eu3+-Activated YxLu1−xNbO4 (x = 0, 0.25, 0.5, 0.75, 1) Solid-Solution Phosphors

Eu3+-doped YxLu1−xNbO4 (x = 0, 0.25, 0.5, 0.75, 1) were prepared by the solid-state reaction method. YNbO4:Eu3+ and LuNbO4:Eu3+ crystallize as beta-Fergusonite (SG no. 15) in 1–10 μm diameter particles. Photoluminescence emission spectra show a slight linear variation of emission energies and intensities with the solid-solution composition in terms of Y/Lu content. The energy difference between Stark sublevels of 5D0→7F1 emission increases, while the asymmetry ratio decreases with the composition. From the dispersion relations of pure YNbO4 and LuNbO4, the refractive index values for each concentration and emission wavelength are estimated. The Ω2 Judd–Ofelt parameter shows a linear increase from 6.75 to 7.48 × 10−20 cm2 from x = 0 to 1, respectively, and Ω4 from 2.69 to 2.95 × 10−20 cm2. The lowest non-radiative deexcitation rate was observed with x = 1, and thus LuNbO4:Eu3+ is more efficient phosphor than YNbO4:Eu3+

Surface Plasmon Enhancement of Eu3+ Emission Intensity in LaPO4/Ag Nanoparticles

A promising way to improve the performance of luminescent materials is to combine them with noble metal nanoparticles. Herein, a set of silver/europium-doped lanthanum orthophosphate (Ag/La0.95Eu0.05PO4) nanostructures with different concentrations of silver nanoparticles were prepared and investigated. The presented overlap between the strongest europium (Eu3+) excitation line and the broad silver nanoparticle surface plasmon resonance makes the combination prospective for coupling. X-ray powder diffraction confirmed the monoclinic monazite structure. The transmission electron microscopy revealed particles with a rod-like shape and ~4 aspect ratio. Photoluminescence spectra show characteristic Eu3+ ion red emission. One of the requirements for an enhanced luminescence effect is the precise control of the distance between the noble metal nanoparticles and the emitter ion. The distance is indirectly varied throughout the change of Ag nanoparticle concentration in the La0.95Eu0.05PO4 host. The emission intensity increases with the increase in Ag nanoparticles up to 0.6 mol %, after which the luminescence decreases due to the nanoparticles’ close packing and aggregation leading to the displacement of La0.95Eu0.05PO4 from the vicinity of the metal particles and reabsorption of the emitted light. The emission intensity of La0.95Eu0.05PO4 increases more than three times when the Eu3+ excitation is supported by the localized surface plasmon resonance in the Ag/La0.95Eu0.05PO4 nanostructures

ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF THE ESSENTIAL OIL AND SOLVENT EXTRACTS OF MENTHA PULEGIUM L.

We report the total phenolic (TPC; expressed as gallic acid equivalents, GAE, per milligram of dry extract weight) and the total flavonoid contents (TFC; expressed as quercetin equivalents, QE, per milligram of dry extract weight) and antimicrobial and antioxidant activities of the essential oil and hexane, diethyl ether, ethyl acetate and methanol extracts of Mentha pulegium L. (Lamiaceae) collected in Serbia. The total phenolic content was in the range of 129.43-388.29 μg GAE/mg, while TFC ranged from 57.81 to 160.94 QE/mg; the highest TPC and TFC were found in the methanol extract. The antimicrobial activity (against five bacteria and two fungi species) of the essential oil and solvent extracts was assessed using disc-diffusion method. However, the studied samples demonstrated a poor antimicrobial potential. The antioxidant activity was screened using five different tests: 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid radical cation decolorization assay (ABTS), total reducing power (TRP), ferric reducing antioxidant power (FRAP) and cupric reducing antioxidant capacity assay (CUPRAC); the methanol extract showed the strongest antioxidant potential. The results of the different antioxidant assays were correlated mutually and with the total flavonoid and total phenolic contents (regression analysis and agglomerative hierarchical clustering). ANTIOKSIDANTNA I ANTIMIKROBNA AKTIVNOST ETARSKOG ULJA I EKSTRAKATA BILJNE VRSTE MENTHA PULEGIUM L.U ovom radu je određen sadržaj ukupnih fenola (TPC; izražen u ekvivalentima galne kiseline, GAE, po miligramu suvog biljnog ekstrakta) i ukupnih flavonoida (TPC; izražen u ekvivalentima kvarcetina, QE, po miligramu suvog biljnog ekstrakta), kao i antimikrobna i antioksidantna aktivnost etarskog ulja i heksanskog, dietil-etarskog, etil-acetatnog i metanolnog ekstrakta biljne vrste Mentha pulegium L. (Lamiaceae; populacija iz Srbije). Sadržaj ukupnih fenola analiziranih uzoraka se kretao u opsegu od 129,43 do 388,29 μg GAE/mg, dok je TFC bio u interval od 57,81 do 160,94 QE/mg; najviše vrednosti za TPC i TFC nađene su za metanolni ekstrakt. Antimikrobna aktivnost (prema pet bakterijskih i dva soja gljivica) etarskog ulja i ekstrakata je određena disk-difuzionom metodom. Proučavani uzorci su imali slabu antimikrobnu aktivnost. Antioksidantna aktivnost je ispitivana pomoću DPPH (2,2-difenil-1-pikrilhidrazil radikal), ABTS (2,2'-azino-bis(3-etilbenzotijazolin-6-sulfonska kiselina radikal katjon), TRP (ukupna redukciona sposobnost), FRAP (sposobnost redukcije feri-jona) i CUPRAC (sposobnost redukcije Cu(II)-jona) metodama; najviši antioksidantni potencijal je imao metanolni ekstrakt. Rezultati različitih metoda za određivanje antioksidantnog potencijala su korelisani međusobno, kao i sa sadržajem ukupnih fenola i flavonoida (regresiona analiza i aglomerativna hijerarhijska klaster analiza). HIGHLIGHTSThe essential oil and hexane, diethyl ether, ethyl acetate and methanol extracts of Mentha pulegium L. collected in Serbia were studied.Their total phenolic content was in the range of 129.43-388.29 μg GAE/mg, while total flavonoid content ranged from 57.81 to 160.94 QE/mg.Solvent extracts (SE) and essential oil of the studied M. pulegium population were poor antimicrobials.Antioxidant activities of SE were studied using five different methods.Differences between the previous and the present results suggest M. pulegium metabolic profile might be influenced by both genetic and environmental factors

Comparison of Three Ratiometric Temperature Readings from the Er3+ Upconversion Emission

The emission of Er3+ provides three combinations of emission bands suitable for ratiometric luminescence thermometry. Two combinations utilize ratios of visible emissions (2H11/2→4I15/2 at 523 nm/ 4S3/2→4I15/2 at 542 nm and 4F7/2→4I15/2 at 485 nm/ 4S3/2→4I15/2 at 545 nm), while emissions from the third combination are located in near-infrared, e.g., in the first biological window (2H11/2→4I13/2 at 793 nm/ 4S3/2→4I13/2 at 840 nm). Herein, we aimed to compare thermometric performances of these three different ratiometric readouts on account of their relative sensitivities, resolutions, and repeatability of measurements. For this aim, we prepared Yb3+,Er3+:YF3 nanopowders by oxide fluorination. The structure of the materials was confirmed by X-ray diffraction analysis and particle morphology was evaluated from FE-SEM measurements. Upconversion emission spectra were measured over the 293–473 K range upon excitation by 980 nm radiation. The obtained relative sensitivities on temperature for 523/542, 485/542, and 793/840 emission intensity ratios were 1.06 ± 0.02, 2.03 ± 0.23, and 0.98 ± 0.10%K−1 with temperature resolutions of 0.3, 0.7, and 1.8 K, respectively. The study showed that the higher relative temperature sensitivity does not necessarily lead to the more precise temperature measurement and better resolution, since it may be compromised by a larger uncertainty in measurement of low-intensity emission bands

Endonuclease heteroduplex mismatch cleavage for detecting mutation genetic variation of trypsin inhibitors in soybean

The objective of this work was to evaluate the genetic variation of trypsin inhibitor in cultivated (Glycine max L.) and wild (Glycine sofa Siebold & Zucc.) soybean varieties. Genetic variations of the Kunitz trypsin inhibitor, represented by a 21-kD protein (KTI), and of the Bowman-Birk trypsin chymotrypsin inhibitor (BBI) were evaluated in cultivated (G. max) and wild (G. sofa) soybean varieties. Endonuclease heteroduplex mismatch cleavage assays were performed to detect mutations in the KTI gene, with a single-stranded specific nuclease obtained from celery extracts (CEL I). The investigated soybean varieties showed low level of genetic variation in KTI and BBI. PCR-RFLP analysis divided the BBI-A type into subtypes A1 and A2, and showed that Tib type of KTI is the dominant type. Digestion with restriction enzymes was not able to detect differences between ti-null and other types of Ti alleles, while the endonuclease heteroduplex mismatch cleavage assay with CEL I could detect ti-null type. The digestion method with CEL I provides a simple and useful genetic tool for SNP analysis. The presented method can be used as a tool for fast and useful screening of desired genotypes in future breeding programs of soybean