scholarly journals Theoretical Estimation of Optimal Linear Cooling Rate for PK-15 Cell Suspension

2021 ◽  
Vol 31 (3) ◽  
pp. 214-222
Author(s):  
Olga Gordienko ◽  
◽  
Igor Kovalenko ◽  
Svitlana Kovalenko ◽  
Larysa Kuleshova ◽  
...  
Keyword(s):  
Cell Suspension ◽  
Cooling Rate ◽  
Thermodynamic Theory ◽  
Cooling Rates ◽  
Damage Rate ◽  
Optimal Linear ◽  
High Cooling Rates ◽  
Activation Type ◽  
Extracellular Environment ◽  
Reduced Time

Preservation of cells during crystallization of the cell suspension is influenced by two types of damaging factors. The first type of cryoinjury occurs during the crystallization of the extracellular environment and is caused by dehydration of cells, increasing the concentration and ionic strength of extracellular and intracellular solutions. As the cooling rate rises, the damage rate of the first type decreases as a result of the reduced time of action of damaging factors. The second type of cryoinjury is intracellular crystallization, the probability of which enhances at high cooling rates, is considered the most destructive to cells. The optimal linear cooling rate for PK-15 cells is determined using a physico-mathematical model, which describes the probability of cryoinjury of cells in the linear freezing mode and is based on the two-factor theory of cryoinjury, thermodynamic theory of homogeneous crystallization and general theory of activation-type processes. The findings have shown that within the range of cooling rates < 0.5 °C/min the cryoinjury of PK-15 cells occurs mainly due to the effects of the solution, and at cooling rates > 2.5 °C/min this was mainly resulted from an intracellular crystallization. The dependence of the percentage of damaged cells on the cooling rate has a relatively wide minimum within the range of cooling rates of 0.5 °C/min… 2.5 °C/min.

Structure and Properties of Leaded Tin Bronze under Different Crystallization Conditions

2013 ◽  
Vol 872 ◽  
pp. 89-93 ◽  
Author(s):  
Nikita Martyushev ◽  
Ilya V. Semenkov ◽  
Yuriy N. Petrenko
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Cooling Rate ◽  
Structure And Properties ◽  
Cooling Rates ◽  
Tin Bronze ◽  
Microstructure Parameters ◽  
Influence Of Crystallization ◽  
Crystallization Conditions ◽  
High Cooling Rates

The influence of crystallization conditions of leaded tin bronze on the obtained microstructure parameters is examined in the paper. Modification of crystallization conditions was realised by varying the cooling rate of the melt with preheating of the casting molds. Quantitative regularities of the influence of the cooling rate of bronze on its phase composition are presented. Data on mechanical properties of the material under investigation are also reported in the paper. It is demonstrated that high cooling rates (casting into mold at ambient temperature) enable obtaining higher mechanical properties in comparison with low cooling rates (casting into mold heated up to 800 °С).

Effect of Si Content on the Size of Fe-Rich Intermetallic Particles in Al-xSi-0.8Fe Alloys

2013 ◽  
Vol 765 ◽  
pp. 107-111 ◽  
Author(s):  
Tharmalingam Sivarupan ◽  
Carlos H. Caceres ◽  
John A. Taylor
Keyword(s):  
Cooling Rate ◽  
Directionally Solidified ◽  
Cooling Rates ◽  
Β Phase ◽  
Intermetallic Particles ◽  
High Cooling Rates ◽  
Si Content

Al-Si-Fe plates with Si contents of 4.5, 9 and 11 mass %, unmodified and Sr-modified, were quasi-directionally solidified in sand moulds with chills at one end. The size and nature of the Fe-rich intermetallics were determined along the plates. Two forms of the intermetallic were observed, α-Al8FeSi and β-Al5FeSi, in proportions and scale dependent on the cooling rate and the Si concentration. The size of the β-phase increased with the concentration of Si at low cooling rates. At high cooling rates the tendency to form α-Al8FeSi phase increased with increasing Si content reducing the size of the β-plates. Modification generally increased the size of the pre-eutectically formed plates while reducing the post eutectically formed ones.

The Thermodynamics of Intracellular Ice Nucleation in the Freezing of Erythrocytes

1975 ◽  
Vol 97 (3) ◽  
pp. 326-332 ◽  
Author(s):  
W. M. Toscano ◽  
E. G. Cravalho ◽  
O. M. Silvares ◽  
C. E. Huggins
Keyword(s):  
Cooling Rate ◽  
Heterogeneous Nucleation ◽  
Numerical Solutions ◽  
Ice Nucleation ◽  
Nucleation Temperature ◽  
Extracellular Medium ◽  
Cooling Rates ◽  
Intracellular Ice ◽  
High Cooling Rates ◽  
Analytical Expressions

A theoretical model describing the thermodynamics of intracellular ice nucleation is developed for red blood cells as a model biomaterial. Analytical expressions based on current theories of ice nucleation by both homogeneous and heterogeneous nucleation processes are coupled with a thermodynamic model for the loss of intracellular water during freezing. Numerical solutions for both modes of nucleation identify two cooling regions—high cooling rates and low cooling rates—separated by a sharp demarcation zone. The nucleation temperature for high cooling rates is approximately 20° K higher than the nucleation temperature for low cooling rates and is essentially independent of cooling rate in each region. The nucleation temperatures for heterogeneous nucleation are approximately 30° K higher than the nucleation temperatures for homogeneous nucleation in the two regions. For the case of heterogeneous nucleation, it is possible to increase the nucleation temperature by packing of catalysts via the concentration polarization effect. If the cell suspension is allowed to supercool before nucleation occurs in the extracellular medium, the sharp transition from low cooling rates to high cooling rates for heterogeneous nucleation shifts to much lower cooling rates. The dependence of the transition cooling rate on the degree of supercooling has been established for a typical freezing situation.

The Effect of Grain Refinement and Cooling Rate on the Hot Tearing of Wrought Aluminium Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 1675-1680 ◽  
Author(s):  
Mark Easton ◽  
John F. Grandfield ◽  
David H. StJohn ◽  
Barbara Rinderer
Keyword(s):  
Grain Size ◽  
Cooling Rate ◽  
Grain Refinement ◽  
Aluminium Alloys ◽  
Grain Morphology ◽  
Hot Tearing ◽  
Grain Refiner ◽  
Cooling Rates ◽  
High Cooling Rates ◽  
Hot Tearing Susceptibility

Using modifications to the Rappaz-Drezet-Gremaud hot tearing model, and using empirical equations developed for grain size and dendrite arm spacing (DAS) on the addition of grain refiner for a range of cooling rates, the effect of grain refinement and cooling rate on hot tearing susceptibility has been analysed. It was found that grain refinement decreased the grain size and made the grain morphology more globular. Therefore refining the grain size of an equiaxed dendritic grain decreased the hot tearing susceptibility. However, when the alloy was grain refined such that globular grain morphologies where obtained, further grain refinement increased the hot tearing susceptibility. Increasing the cooling decreased the grain size and made the grain morphology more dendritic and therefore increased the likelihood of hot tearing. The effect was particularly strong for equiaxed dendritic grain morphologies; hence grain refinement is increasingly important at high cooling rates to obtain more globular grain morphologies to reduce the hot tearing susceptibility.

The effect of cooling rate on crystallization behavior and tensile properties of CF/PEEK composites

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Cooling Rate ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Crystalline Polymer ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Cooling Rates ◽  
Control Range ◽  
Temperature Range ◽  
Transverse Tensile

Abstract In this study, the differential scanning calorimetry (DSC) tests were performed to measure the nonisothermal crystallization behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites under different cooling rates. The characteristic parameters of crystallization were obtained, and the nonisothermal crystallization model was established. The crystallization temperature range of the material at different cooling rates was predicted by the model. The unidirectional laminates were fabricated at different cooling rates in the crystallization temperature range. The results showed that the crystallization temperature range shifted to a lower temperature with the increase of cooling rate, the established nonisothermal crystallization model was consistent with the DSC test results. It is feasible to shorten the cooling control range from the whole process to the crystallization range. The crystallinity and transverse tensile strength declined significantly with the increase of the cooling rate in the crystallization temperature range. The research results provided theoretical support for the selection of cooling conditions and temperature control range, which could be applied to the thermoforming process of semi-crystalline polymer matrixed composites to improve the manufacturing efficiency.

Effects of RE on Critical Cooling Rate of Bearing-B Steel

2012 ◽  
Vol 535-537 ◽  
pp. 761-763 ◽  
Author(s):  
Yi Sheng Zhao ◽  
Xin Ming Zhang ◽  
Zhi Guo Gao
Keyword(s):  
Phase Change ◽  
Cooling Rate ◽  
Experimental Results ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
The Law

The law of phase change of bearing-B steel during continual cooling was studied by adopting dilatometer. The CCT curves of bearing-B steel were drawn, and the effects of RE on critical cooling rates were studied. The experimental results show that the start temperatures of martensite TM was decreased from 438 to 404°C. The critical cooling rate was simultaneously decreased from 33 to 15°C/s.

Effects of the Cooling Rate on the Acoustic Properties of Pb-10Sn Solder

2012 ◽  
Vol 729 ◽  
pp. 356-360
Author(s):  
Endre Harkai ◽  
Tamás Hurtony ◽  
Péter Gordon
Keyword(s):  
Sound Velocity ◽  
Cooling Rate ◽  
Acoustic Microscopy ◽  
Acoustic Properties ◽  
Scanning Acoustic Microscopy ◽  
Cooling Rates ◽  
Reliability Parameters ◽  
Microscopy Characterization ◽  
The Given

Microhardness and sound velocity were measured in case of differently prepared solder samples. The used Pb-10Sn solder samples were melted then cooled down applying different cooling rates. These procedures caused variant microstructure thus different microhardness and sound velocity values. The sound velocity was measured by means of scanning acoustic microscopy. Characterization of solder materials by acoustic microscopy gives the possibility to non-destructively estimate mechanical and reliability parameters of the given material.

The effect of various cooling rates on the membrane ultrastructure of frozen human erythrocytes and its relation to the extent of haemolysis after thawing

1981 ◽  
Vol 49 (1) ◽  
pp. 369-382
Author(s):  
S. Fujikawa
Keyword(s):  
Cooling Rate ◽  
Human Erythrocytes ◽  
Ice Crystals ◽  
Erythrocyte Membranes ◽  
Ultrastructural Changes ◽  
Cooling Rates ◽  
Intracellular Ice ◽  
Frozen State ◽  
Membrane Ultrastructure ◽  
Fast Freezing

Human erythrocytes suspended in buffered isotonic saline were frozen to the temperature of liquid nitrogen at various cooling rates of 3, 140, 700, 1800, 3500, 8000 and 11 500 deg. C/min. The membrane ultrastructure in the frozen state and the extent of haemolysis after thawing were examined at each cooling rate. As the cooling rates increased from 3 to 3500 deg. C/min, the extent of lysis gradually decreased, but further increase in cooling rates in excess of 8000 deg. C/min resulted in an abrupt increase of lysis. Membrane-associated vesicles devoid of intramembrane particles (IMPs) were formed in the erythrocyte membranes frozen at cooling rates slower than 1800 deg. C/min. The frequency and size of these vesicles were highly cooling-rate-dependent and they were no longer formed in the erythrocyte membranes frozen at cooling rates faster than 3500 deg. C/min. Another membrane ultrastructural change associated closely with the formation of intracellular ice crystals appeared at cooling rates faster than 8000 deg. C/min. The membrane regions in direct contact with intracellular ice crystals were physically damaged and had an appearance resembling worm-eaten spots. The erythrocytes frozen at a cooling rate of 3500 deg. C/min exhibited ultrastructural integrity of the membrane by avoiding the membrane changes caused by either slow or fast freezing. It is suggested, from the close relation between membrane ultrastructure and the extent of haemolysis, that the ultrastructural integrity of membrane in the frozen state is important for avoiding haemolysis after thawing, and that the membrane ultrastructural changes caused by both slow and fast freezing were responsible for the lysis after thawing.

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