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Van Do P.,Dong - A University | Tuyen V.P.,Hanoi University of Science and Technology | Quang V.X.,The University of Da nang | Hung L.X.,The University of Da nang | And 4 more authors.
Optical Materials

The absorption, luminescence, Raman spectra and lifetimes of Sm-doped alkali telluroborate glasses (TB glasses) TB:Sm3+ have been investigated. The dual energy transfers including energy transfer between Sm3+ - Sm3+ pairs and Sm3+ - non-bridging oxygen (NBO) intrinsic defects were investigated. The concentration quenching of luminescence intensity was explained by the non-radiative energy transfer between the Sm3+ ions through the cross-relaxation mechanism. The decay curves are single exponentials with low concentrations (lower 0.10 mol%) and become non-exponentials at higher concentrations. The non-exponential decay curves are fitted to the Inokuti and Hirayama model to give the energy transfer parameters between Sm3+ ions. The dominant interaction mechanism for energy transfer process is dipole-dipole interaction. The energy transfer induced Sm3+ photoluminescence enhancement in tellurite glass was experimentally studied and confirmed. © 2016 Elsevier B.V. All rights reserved. Source

Zakharenko A.M.,RAS Pacific Institute of Bioorganic Chemistry | Kusaykin M.I.,RAS Pacific Institute of Bioorganic Chemistry | Kovalchuk S.N.,RAS Pacific Institute of Bioorganic Chemistry | Sova V.V.,RAS Pacific Institute of Bioorganic Chemistry | And 6 more authors.
Biochemistry (Moscow)

A specific 1→3-β-D-glucanase with molecular mass 37 kDa was isolated in homogeneous state from crystalline style of the commercial marine mollusk Tapes literata. It exhibits maximal activity within the pH range from 4.5 to 7.5 at 45°C. The 1→3-β-D-glucanase catalyzes hydrolysis of β-1?3 bonds in glucans as an endoenzyme with retention of bond configuration, and it has transglycosylating activity. The Km for hydrolysis of laminaran is 0.25 mg/ml. The enzyme is clas- sified as a glucan endo-(1→3)-β-D-glucosidase (EC The cDNA encoding this 1→3-β-D-glucanase from T. lit- erata was sequenced, and the amino acid sequence of the enzyme was determined. The endo-1→3-β-D-glucanase from T. literata was assigned to the 16th structural family (GHF 16) of O-glycoside hydrolases. © Pleiades Publishing, Ltd., 2012. Source

Thanh N.T.,Vietnam Academy of Science and Technology | Quang V.X.,Vietnam Academy of Science and Technology | Tuyen V.P.,Vietnam Academy of Science and Technology | Tam N.V.,Nha Trang Institute of Technology Research and Application | And 2 more authors.
Optical Materials

Judd-Ofelt parameters of Eu 3+-doped alkali and earth alkali fluoro-aluminoborate glasses are determined from the fluorescence spectra. The dependence of these parameters on the compositional changes of the materials is discussed. The glass containing sulphatecomponent shows the larger values of Ω compared with the fluoro-aluminoborate glasses because of higher DCT (Eu 3+-F -) values. The difference of ionic radius and electronegativity between Na and Ca lead to higher O 2 parameter of CaF 2-Al 2O 3-B 2O 3:Eu 3+ glass. Persistent spectral hole burning has been observed in Eu 3+ ions doped alkali-and earth alkali fluoro-aluminoborate glasses with the compositions of 16NaF·73B 2O 3· 8Al 2O 3·3Eu 2O 3 and 16CaF 2·73B 2O 3·8Al 2O 3·3Eu 2O 3, which have been prepared using conventional melting technique. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved. Source

Hanh H.K.,1 Tran Phu | Tuan T.D.,Nha Trang Institute of Technology Research and Application | Tuat T.V.,Nha Trang Institute of Technology Research and Application | Kinh D.V.,Nha Trang Institute of Technology Research and Application | Dung P.T.,Institute of Materials Science
Radiation Measurements

The thermoluminescence (TL) characteristics of natural zircons from Vietnam were studied for potential application to TL dating. All the glow curves of samples irradiated by gamma radiation or UV light showed a complex structure that consisted of a low temperature part (LTP) and a high temperature part (HTP). The TL emission spectra and monochromatic glow curves indicate that the two main impurities governing the TL emission are Dy3+ (LTP) and Tb3+ (HTP). The anomalous fading of the TL signal was assigned to the emission associated with Dy3+ whereas the 545 nm emission associated with Tb3+, exhibits significantly lower fading and consequently more suitable for TL dating. © 2012 Elsevier Ltd. All rights reserved. Source

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