| Ice temperature preservation is a newly developed technology in recent years. Thispaper takes the prolonging of complex biological organs preservation as its background andstudies heat value transfer process which occurs during ice temperature preservation byapplying biology, thermal physics, clinical medicine, etc. The study targets of this thesisconsist of low temperature preservation of the most basic biologic unit–cell as well as theice temperature preservation and transplantation of an entire organ. Both under micro andmacro level, and through comparison with current clinical preservation methods, the heatand mass transfer mechanism of ice temperature preservation technology, when applied tocomplex biological tissue, were explored.This thesis targets on kidney epidermis cell and studies its permeability characteristics,which include non-permeable volume of cell, osmotic coefficient of cell membrane againstwater and low temperature protective agent, etc., under different temperature and osmoticpressure by microscope image analytical method. As the result shows, the average cellisosmotic volume Viso=2472.58μm3when put in isosmotic solution; the non-permeablevolume Vb=0.22Viso. The osmosis coefficient of kidney epidermis cell to waster (Lp) andthat to low temperature protective agent (Ps) as well as to activation energy (Ea) in dimethylsulfoxide, ethylene glycol and glycerite under different temperature were got throughobserving the osmosis response of cells in low temperature protective agent and furtherapplying parametric model.Among various biological heat transfer models, porous medium model, which consistsof porous framework that is constructed by cell and humoral channels that are composed ofblood capillary, lymph-vessels and for blood flow, can best represent characteristics of akidney. To study porous medium model, the physical property of porous medium shall bemeasured. Two basic characteristic parameters of kidney as porous medium were analyzedin this paper, namely porosity and permeability. As it turned out, the porosity of swinekidney Φ=15.64%, permeability K=14.5μm2. These data provide experimental basis fornumerical simulation of kidney cold perfusion.The cold perfusion process of detached kidney is a crucial step in ice temperaturepreservation, and thus studies about changes of temperature field during that process bearsimportant clinical significance. In kidney cold perfusion, surface and internal temperatureof kidney were overall monitored, on the basis of which, kidney vein vessel and shape werethree-dimensionally reconstructed by vessel molding. After getting the physical model ofkidney, which was later imported in Fluent, the three-dimensional temperature field can be reconstructed with the combination of laminar flow model and porous medium model.Through comparing simulated result and experimental result, the thermodynamics effectcaused by cooling function under cold stimulation was explored, with simulated results oftemperature field applied in various ways.At last, on the basis of above research, clinical experiment of autoplastictransplantation was conducted practically. After36hours of ice temperature preservationunder-0.8℃, the kidney was re-implanted into swine’s body. Four days later, all of itsphysical signs returned to normal. The experiment shows that ice temperature preservationcould restrain basic metabolic rate of cell and reduce cellular energy consumption. Whencompared with traditional clinical preservation methods, ice temperature preservation couldfurther lower storage temperature by4to5℃and prolong preservation time from thetheoretical16hours to a practical36hours, making this method a quite promising one infuture low temperature preservation.This thesis is funded by Natural Science Foundation of China (Project Number: No.51076117)... |
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