Paju A.,Tallinn University of Technology |
Pari M.,Tallinn University of Technology |
Selyutina A.,University of Tartu |
Zusinaite E.,University of Tartu |
And 6 more authors.
Nucleosides, Nucleotides and Nucleic Acids | Year: 2010
A series of novel acyclic thymine nucleoside analogues were prepared by the Mitsunobu reaction from appropriately protected chiral triols. The enantiomeric triols were obtained from substituted-lactone acids, prepared by asymmetric oxidation of 3-substituted-1,2-cyclopentanediones. The cytotoxic activity of new analogues was evaluated on MCF-7 human breast cancer and HeLa cells, and antiviral activities on human immunodeficiency virus type 1 and hepatitis C virus models. The synthesized compounds revealed specific anti-retroviral activity and no cytotoxic side effects. © Taylor and Francis Group, LLC.
Tatte T.,University of Tartu |
Hussainov M.,University of Tartu |
Paalo M.,University of Tartu |
Part M.,University of Tartu |
And 10 more authors.
Science and Technology of Advanced Materials | Year: 2011
The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO2, TiO2, ZrO2, HfO2 and CeO2) fibres with a high aspect ratio (up to 10 000) and a diameter as small as 200 nm. The sol-gel processing includes consumption of precursors obtained from alkoxides by aqueous or non-aqueous polymerization. Shear thinning of the precursors enables pulling a material into a fibre. This rheological behaviour can be explained by sliding of particles owing to external forces. Transmission (propagation) of light along microscaled fibres and their excellent surface morphology suggest that metal oxide nanofibres can be directly drawn from sol precursors for use in integrated photonic systems. © 2011 National Institute for Materials Science.
Rebane A.,Montana State University |
Rebane A.,National Institute of Chemical and Biological Physics |
Drobizhev M.,Montana State University |
Makarov N.S.,Montana State University |
And 3 more authors.
Journal of Luminescence | Year: 2010
Stark effect, in combination with spectral hole burning and single-molecule spectroscopy, has been a fruitful technique to study permanent electric dipole moment of molecules in condensed phase. However, because measuring Stark shifts relies on external fields and narrow line- or hole-widths, the applicability of this method at ambient conditions required by most biological systems has remained limited. Here we demonstrate a new all-optical method for measuring the molecular dipole moment difference between ground and excited states using two-photon absorption (2PA) spectroscopy. We show that the value and orientation of the static dipole moment difference can be determined from the corresponding absolute 2PA cross-section. We use this new method to determine for the first time the strength of local electric field Eloc=0.11.0×10 8 V/cm inside beta-barrel of Fruit series of red fluorescent proteins. Because our method does not rely on external field and is applicable in liquid solutions, it is well suited for the study of biological systems. © 2009 Elsevier B.V.
Siimer K.,Tallinn University of Technology |
Kaljuvee T.,Tallinn University of Technology |
Pehk T.,National Institute of Chemical and Biological Physics |
Lasn I.,Parnu Plaaditehas AS
Journal of Thermal Analysis and Calorimetry | Year: 2010
Thermal behaviour of industrial UF resins modified by low level of melamine was followed by TG-DTA technique on the labsys TM instrument Setaram together with the 13C NMR analysis of resin structure and testing boards in current production at Estonian particleboard factory Pärnu Plaaditehas AS. DTA curve of UF resin which has been cocondensed during synthesis with even low level of melamine shows the shift of condensation exotherm and water evaporation endotherm to considerable higher temperatures. The effect of melamine monomer introduced to UF resin just before curing was compared. The effect of addition of urea as formaldehyde scavenger was studied. © 2009 Akadémiai Kiadó, Budapest, Hungary.