Исследовано мицеллообразование в растворах криопротекторов -оксиэтильных производных гли-церина со степенью полимеризации n=5 и n=25 (ОЭГ n=5 , ОЭГ n=25 ), а также в криозащитных средах на основе комбинации этих соединений с диметилацетамидом (ДМАЦ). Определены значения критиче-ской концентрации мицеллообразования (ККМ) растворов ОЭГ n=5 , ОЭГ n=25 и комбинированных сред на их основе сталагмометрическим методом. С увеличением степени полимеризации глицеринов от n=5 до n=25 повышаются значения ККМ за счет увеличения гидрофильности соединений. В комбини-рованных средах ОЭГ n=5 :ДМАЦ и ОЭГ n=25 :ДМАЦ значения ККМ уменьшаются за счет появления сме-шанных мицелл.Ключевые слова: мицеллообразование, критическая концентрация мицеллообразования, окси-этилированные глицерины, комбинированные криозащитные среды, поверхностное натяжение, изо-терма поверхностного натяжения. ВведениеПерспективным направлением создания эффективных криозащитных сред для низкотемпе-ратурного консервирования различных клеток и тканей в последние годы является использова-ние комбинации двух и более криопротекторов в криоконсервантах [1-2]. Такой подход позво-лил значительно улучшить результаты криоконсервирования различных биологических объек-тов, в том числе клеток крови, повысить суммарную концентрацию криопротекторов в крио-консервантах без увеличения их цитотоксического действия и т.д. Кроме того, во многих рабо-тах описывается эффект «нейтрализации токсичности криопротекторов» за счет использования разных комбинаций криозащитных соединений в средах [3].Комбинированные криозащитные среды имеют в своем составе два и более ПАВ (криопро-тектора), отличающихся химической структурой, физико-химическими свойствами, механиз-мом криозащитного действия и т.д. Определение ККМ растворов отдельных криопротекторов, комбинированных криозащитных сред и смесей ПАВ различных типов имеет важное значение для описания различных коллоидно-химических процессов и адсорбции. В смесях ПАВ сильно снижается поверхностное натяжение и ККМ [4][5].В наших исследованиях на протяжении многих лет большое внимание было уделено изуче-нию оксиэтильных производных глицерина -их синтезу, исследованию физико-химических свойств, токсичности, комплексному изучению криопротекторных свойств [1]. Оксиэтилиро-ванные глицерины являются хорошо растворимыми в воде полимергомологами и малотоксич-ными веществами. Исследование молекулярно-массового распределения оксиэтильных произ-водных глицерина со степенью полимеризации n=5 и n=25 (ОЭГ n=5 и ОЭГ n=25 ) показало, что синтезированные олигомеры являются полидисперсными соединениями, содержащими смесь полимергомологов с различной молекулярной массой. Установлена криозащитная эффектив-ность ОЭГ n=5 , ОЭГ n=25 и комбинированных сред на их основе при криоконсервировании клеток крови [6][7]. Так, ОЭГ n=5 проявил выраженную криопротекторную активность в отношении тромбоцитов, а ОЭГ n=25 обеспечивает высокую сохранность эритроцитов при их заморажива-нии.Цель настоящей работы -исследование процесса мицеллообразования в растворах оксиэти-лированных глиц...
The physicochemical properties (surface tension, dynamic viscosity, crystallization and melting temperatures) of polyvinyl alcohol solutions of molecular weight 9, 31 and 72 kDa have been studied. The surface tension and the critical concentration of micelle formation were determined by the method of stalogometry, and the dynamic viscosity was determined using an Oswald viscometer. The crystallization and melting temperatures were determined in a cooled modified chamber of the UOP-6 software freezer at a rate of 2°C/min. Cryomicroscopic studies were carried out on a polarizing microscope "MIN-8". The surface tension reflects the interaction of PVA solutions with the lipid layer of biomembranes and indicates the hydrophobic properties of substances. The viscosity of PVA solutions characterizes their interaction with water molecules and reflects hydrophilic interactions. The purpose of the study is to determine the physicochemical properties of PVS that characterize the hydrophilic-hydrophobic interactions in the studied solutions and the micelle formation of PVА solutions of different molecular weights. Materials and methods. Studies of the dynamic viscosity and density of 0.1%-1% PVA solutions of molecular weight 9, 31 kDa showed that these parameters increase with increasing PVA concentration, which leads to increased hydrophilicity of the solutions. Results and discussion. It was shown that the surface tension of PVA solutions decreases with increasing concentration, which leads to a decrease in the hydrophobic properties of the polymer. It was found that in 0.5% PVА solutions of molecular weight 9 and 31 kDa the crystallization and melting temperatures decrease from -5 to -6°C. At these temperatures, crystallization and melting of the solutions begin. Conclusion. The study of micelle formation in PVА solutions of different molecular masses was carried out, surface tension isotherms were constructed, and the break point on the isotherm corresponding to the CCM was determined. The values of the critical concentration of micelle formation of PVА of molecular masses 9, 31, 72 kDa were determined. Hydrophobic links of PVА of molecular masses 9 and 31 kDa form hydrophobic cavities in the micelle structure, which can reduce recrystallization activity
Preventing crystallization of the liquid phase during freeze-thawing of cells is one of the main problems that need to be solved for the successful preservation of biomaterial at low temperatures. One highly effective recrystallization inhibitor is polyvinyl alcohol (PVA). However, the mechanisms of its cryoprotective effect have not been finally elucidated. In particular, it is not clear which structural features contribute to the realization of the antirecrystallization properties of PVA in the region of its cryoprotective concentrations. The influence of PVA on solvent crystallization and structural rearrangements of associations of PVA molecules in phosphate-buffered saline (PBS) was experimentally investigated. Solutions of PVA (molecular weight 9 kDa) in PBS were studied by cryomicroscopy and fluorescence spectroscopy methods. It was shown that molecular associations of PVA in PBS undergo a rearrangement of about 0.5−1 wt%, which is accompanied by a change in their size and hydrophilic-hydrophobic properties. PVA also changes the morphological structure of ice upon cooling and prevents crystallization upon heating. It is suggested that the mechanism of the antirecrystallization activity of PVA may be due to the formation of its complexes with the surface of ice crystals.
An equipment and method are proposed for displacing hot loads on account of their heat. Applications are considered for container pipe transportation in nonferrous metallurgy.To save energy from external sources in the transportation of hot loads, it is proposed to displace them on account of their heat. A device for this 2 includes the container 1 (Fig. 1a ) with sleeve seal 2 moving in the pipeline 3. In the front of the container in the vessel 4 containing the hot load there is a sealed vessel 5 filled for example with water. Vessel 5 communicates with the water jacket 6 ( Fig. 1b ), which serves to preheat the water on contact with the hot load and to reduce the heat transfer by the load-bearing structure 7 in the container. The water jacket in turn communicates with the heat exchanger 8, which is located in the hot load. At the output from the heat exchanger there is the valve 9 adjusted to the design pressure in the pipe 3. To reduce the dynamic and thermal loads on the load-bearing structure 7, the container is suspended by the rollers 10 with gap to the load-bearing structure.The container 1 placed in the inclined part 11 (Fig. 1c ) in the receiving station is retained by the pin 12 and filled with water. After slide valve 13 is opened, the container is freed from the pin and passes into the part 14, and the next container replaces it. In the loading section, the container is loaded with the transported material with steam formation temperature, after which the lid 15 of the loading section 16 and the slide valve 13 are closed, while slide valve 17 is opened. The water poured into vessel 5 (Fig. 1, a -c) of the container 1 and the water in the jacket 6 are heated by the hot material to the evaporation temperature and pass into the heat exchanger 8, in which they are transformed into steam. The steam acts on the valve 9 adjusted to the design pressure and enters the closed cavity between the container 1 and the slide valve 13 in the loading section. The compressed steam acts on the sleeve seal 2 and the container begins to move. After the container has passed the gate valve 17, it is closed, and the container continues to move through the pipe 3.
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