Acoustic emission during cooling and heating of aqueous solutions of polyethylene glycols of molecular masses from 300 to 3000.

The object of this research is to study acoustic emissions (AE) in aqueous solutions of polyethylene glycols (PEGs) of molecular masses from 300 to 3000 during cooling at 100 degrees C/min and heating at 70 degrees C/min in the temperature range from 0 to -196 degrees C. The dependence of AE intensity on PEG concentration and molecular mass is analysed. The AE intensity correlated with the crystalline to amorphous phase ratio in the frozen system.

On phase transitions in the water-ethylene glycol system at subzero temperatures under non-isothermal conditions.

The dynamic phase diagrams of the water-ethylene glycol (EG) system have been plotted at the warming rate of 0.4 degrees C/min(-1) after cooling of samples down to -196 degrees C by quenching in liquid nitrogen or slow cooling at the rate of approximately 0.15 degrees C/min(-1). The melting of two stable eutectics at the temperatures of -42.7 degrees C and -48.7 degrees C and the metastable eutectic at -63 degrees C was observed. Hydrates 1:1 crystallized separately from ice during warming both after quenching and after slow cooling. Glass devitrification and EG:3H(2)O hydrate melting took place during warming of the samples after quenching but these thermal features were absent after slow cooling in the EG concentration range of 42.0 - 63.5 weight percent. The notions about two-stage mechanism of ice nucleation in EG aqueous solutions might be critically revised

[Functional status of cryopreserved rat liver mitochondria]. / Izuchenie funktsional'nogo sostoianiia kriokonservirovannykh mitokhondrii pecheni krysy.

Mitochondria from the rat liver have been frozen down to -196 degrees C under protection of dimethylsulfoxide, after which they were subjected to periodical increase and decrease in temperature (cycling) in the ranges of -105 degrees C to -196 degrees C or -135 degrees to -196 degrees C. There have been observed some non-lethal damages of mitochondria which were revealed in the decrease in the respiratory control and in the ADP/O ratio after the cycling. The damage rate increased with the increase of the number of temperature decrease-increase cycles. The damages were also greater in the case when the upper limit of cycling temperature was higher than the glass transition temperature of the freezing medium (Tg = -126 degrees C). The non-lethal damages of mitochondria are explained by the influence of electric fields, appearing in the frozen sample during the temperature increase or decrease.

[Metabolism macroergic compounds in erythrocytes in the initial forms of cerebrovascular diseases]. / Metabolizm makroérgicheskikh soedinenii v éritrotsitakh pri nachal'nykh formakh sosudistykh zabolevanii golovnogo mozga.

The spectra of 31P-NMR erythrocytes in patients with initial symptoms of cerebral circulation insufficiency compared to blood-donors were analysed. The expansion of 31P-NMR ATP and 2,3-DPG signals is observed in pathology. On these grounds the authors have come to a conclusion that the population of erythrocytes is more heterogeneous as to oxygen saturation than in normal state.

[Distribution of certain nonelectrolytes between intra- and extracellular parts of erythrocytes]. / Raspredelenie nekotorykh ne elektrolitov mezhdu vnutri- i vnekletochnoi sredo 'eritrotsitov.

Human red blood cells were balanced at 37 degrees C in 15% solution of the following nonelectrolytes (NE): methanol, ethanol, 1,2-propanediol, diethylene glycol, glycerol, polythelene glycols (PEGs) with molecular masses 300, 400, 600, 1000, 15000. The distribution coefficients (Q) equal to the ratio of the N concentration in cell to that in the intercellular medium, were determined by 1H-NMR technique. A monotonous decrease of the Q values with the increase of the molecular mass of the NE from 1.15 + 0.12 for methanol to 0.12 +/- 0.01 for PEG-1500 has been demonstrated. Results obtained demonstrate that the mixture (PEG) components with different molecular weights and 1,2-PD-PEG-1500 take negligible influence on the distribution coefficients of these substances between erythrocytes and extracellular environment.