Ludmila Yu. Minakova

The Influence of Zn3(PO4)2:Mn - Luminophores Synthesis Conditions on their Surface and Luminescent Features

A technology, that allows production effective x-ray luminescent phosphors Zn3(PO4)2:Mn2+ with nanosized particles from the water solution by sol-gel method, and directional regulated their luminescence color from green to red was developed. X-ray intensity and spectra, phase structure, and surface properties of synthesized samples depending on the synthesis conditions was studied. The conditions of synthesis which allow to obtain the samples according to the demands for the luminophores of medical assignment were determined.

Luminescent Materials on the Basis of Yttrium Oxide and Yttrium Aluminum Garnet Used for Photodynamic Therapy

Finely-dispersed phosphors of Y2O3:Eu and Y3Al5O12:Eu have been synthesized with the help of Pechini method and the method of self-propagating high-temperature synthesis (SHS). During the synthesis of phosphors on the basis of Y2O3 carried out with Pechini method the size of crystallites increases with the enlargement of concentration of yttrium, but it decreases when the method of SHS is applied. The structure of phosphors on the basis of Y3Al5O12 (YAG) is strongly amorphized. This fact agrees with the data of XRD and with the prevalence of the band with λmax = 613 nm in the spectra of this phosphor. The enlargement of yttrium concentration in it promotes the amorphisation of yttrium aluminum garnet and the decrease of a crystal phase content. The sample of Y3Al5O12:Eu synthesized with Pechini method has the maximum intensity, while in conditions of excitement with “high-level” X-ray radiation which corresponds to the radiation of industrial medical X-ray apparatus, the phosphor of Y2O3:Eu synthesized with the help of SHS showed the largest intensity. Colloid solutions prepared with the use of the samples synthesized by SHS method revealed a higher steadiness and a lower disposition to the sedimentation process. The samples of Y2O3:Eu phosphor possessing the smallest size of particles and the highest intensity of X-ray luminescence are the most suitable for the creation of pharmacological drugs used for photodynamic therapy.

Insights into Receptive Processing of Authentic Foreign Discourse by EFL Learners

Learning a foreign language nowadays is not just remembering words and grammar rules; it is a process of penetration into the hidden meaning of the message. Context plays a major role in the success of oral comprehension. This investigation looks at the issue of perception of authentic speech from the perspective of discourse approach. The authors study various factors influencing EFL learners’ comprehension of authentic English American speech. Our observations and empirical data have led us to believe that there are some major difficulties of comprehension in the level of discourse which include not only unknown words but also lack of cultural awareness and pragmatic competence. Problems arise when the learners cannot infer the right meaning of the utterance because their perception stays in the vocabulary or grammar level without integrating both linguistic and extra linguistic features of the context of communication.