Kazakh State University
Kazakh State University
Batyrbekov Y.O.,Bekturov Institute of Chemical Sciences |
Rakhimbaeva D.,Kazakh State University |
Musabekov K.,Kazakh State University |
Zhubanov B.,Bekturov Institute of Chemical Sciences
Materials Research Society Symposium Proceedings | Year: 2010
Alginate based microparticle drug delivery systems were prepared for the sustained release of antitumor drugs. Two drugs, cyclophosphane and 5-fluorouracil, were encapsulated into the microparticles. The drug loaded microparticles were fabricated using a very convenient method under very mild conditions by the gelation of alginate with calcium cation. Modified microparticles were obtained by syringed dropwise a solution of drugs in sodium alginate into chitosan solution in calcium chloride. The effect of polymers concentration and the drug loading (1.0, 5.0 and 10%) on the release profile of drugs were investigated. The amount of drug release was much higher initially (approximately 25%), followed by a constant slow release profile. All the release data show the typical pattern for a matrix controlled mechanism. The cumulative amount of drug released from alginate gels was linearly related to the square root of the time and the release rate decreased this time. The process is controlled by the diffusion of antitumor drugs through the chitosan coating. Scanning electron microscopy (SEM) and particle size analysis revealed differences between the formulations as to their appearance and size distribution. The experiments for anticancer action of alginate microparticles were determined at 120 inbreeded white rats (females, weight 120-125 g, age 2-3 month) infected by malignant Rhabdomyoma strain at the dose of 10 000 cells. Medical-biological tests show that the duration of anticancer activity for the drug-containing alginate microparticles increases at 5-8 times in comparison of free drugs. Such systems may have potential for controlled delivery of antitumor drugs for the treatment of eye cancer. © 2010 Materials Research Society.
Mamilov A.,Kazakh State University |
Dilly O.,University of Hamburg
Geomicrobiology Journal | Year: 2011
Geochemical shifts in carbon cycling induced by agriculture in arid and semiarid ecosystems are closely linked to global climate. Here, we evaluated (i) how different agricultural practices in arid steppe ecosystems of north Kazakhstan influenced CO 2/O 2 exchange rate, respiratory quotient (RQ), and C-transformation efficiency and (ii) shifts in δ 13C-CO 2 signature induced by longterm and uniform agricultural practices when a natural C3-plant community was infstituted with a C3-crop. Conservation tillage and intensive mold-board ploughing were compared with soil that had never been tilled. The content of microbial C was significantly lower in soil infjected to tillage. For all tilled treatments RQ was close to 1.0 and higher than in never tilled soil suggesting complete oxidation of soil organic matter. δ 13C-CO 2 value for never tilled soil was significantly lower (-26%) than in all tilled treatments (around -20%), suggesting that agricultural soils produce CO 2 with heavier isotope composition compared with undisturbed soil. © Taylor & Francis Group, LLC.
Tazhibayeva I.,RAS Research Center Kurchatov Institute |
Beckman I.,Moscow State University |
Shestakov V.,Kazakh State University |
Kulsartov T.,RAS Research Center Kurchatov Institute |
And 5 more authors.
Journal of Nuclear Materials | Year: 2011
Proposed mathematical and software analysis of reactor experiments allowed interpretation of the experimental results of a tritium release study. Tritium was continuously generated by the reaction of lithium-6 with thermal neutrons for various thermal conditions of lithium metatitanate (Li2TiO 3). The main gas release parameters were calculated in order to assess the potential use of lithium metatitanate in tritium breeders. These parameters were: gas release rate, tritium retention, retention time, activation energy for thermal desorption as HT, activation energy for volume diffusion as +, and the corresponding pre-exponential (frequency) indexes. © 2010 Elsevier B.V. All rights reserved.