Study On The Effect Of Auxiliary Magnetic Field Quick Freezing Technology On Plasma Freezing

With the development of cryobiology,cryopreservation of various biomaterials has become an important research field.Plasma,as an important biomaterial in clinical medicine,plays an important role in the delivery of energy and substances,elimination of metabolism and so on in human life activities.At the same time,for some patients with congenital and acquired ischemic factors,we can carry out targeted clinical treatment through the delivery of plasma.Nowadays,with the rapid freezing process(air-cooled,air-cooled and plate contact)becoming more and more mature,it is difficult to achieve a substantial breakthrough in the improvement of the original process.Therefore,it leads to ultrasonic assisted,high-pressure assisted,magnetic field assisted and other auxiliary freezing means to further improve the freezing rate.This paper focuses on more efficient preservation of fresh frozen plasma as the research content,on the basis of air-cooled freezing,trying to achieve the purpose of further improving the quick freezing by magnetic field assisted freezing.The specific research contents are as follows:(Ⅰ).According to the empirical formula,the plasma physical parameters(density,specific heat capacity,thermal conductivity,etc.)are comprehensively calculated,the temperature gradient distribution of plasma under air cooling is simulated,and the temperature changes of different probe points in plasma freezing process and quick freezing process are obtained,which provides a certain numerical theoretical basis for future experiments.(Ⅱ).Taking pig plasma as the research object,the experimental temperature curves of pig plasma under 0-100 Gs magnetic field intensity were compared.The freezing process of plasma molecules was observed under the microscope,and the optimal magnetic field intensity was determined to improve the cooling rate.(Ⅲ).After the quick freezing experiment,the contents of plasma protein and coagulation factor VIII under 0-100 Gs magnetic field intensity were measured,and the contents of fresh frozen plasma components were compared to analyze and determine the quality effect of magnetic field assisted quick freezing.Through theoretical and numerical simulation analysis,the following results can be obtained:(Ⅰ).During the plasma freezing process,different measuring points have different effects on the plasma temperature,showing different temperature performance from the plasma bottle to the plasma center,mainly because the heat transfer mode on the surface of the plasma bottle is mainly natural convection,while the heat transfer mode inside the plasma is mainly heat conduction.At the same time point,the change of cooling rate from plasma bottle wall to plasma geometric center temperature changed from fast to slow.(Ⅱ).In the comparison of plasma freezing experiments under 0-100 Gs,the difference of plasma temperature drop curves under different magnetic field intensities mainly appears in the phase transition stage,and the maximum promotion effect is achieved when the magnetic field intensities are 60 Gs and 80 Gs.Under different magnetic field intensities,the freezing time,supercooling degree,freezing speed and plasma water content of the crystallization section are affected by the magnetic field,but there is no obvious correlation between the freezing time of the precooling section and the cryogenic section.(Ⅲ).When the magnetic field is frozen at 60 and 80 Gs,the ice crystals are smaller and have regular shape,which indicates that the magnetic field has an influence on the size and shape of nucleating ice crystals.The influence of magnetic field is mainly reflected in the effect of phase transition on the nucleation of ice crystals.Through the influence of magnetic field,more molecular clusters are easier to reach the minimum critical radius size,so that the crystallization is easier to occur and the phase transition is faster.(Ⅳ).The plasma protein content and coagulation factor VIII content decreased in different degrees under different magnetic field intensities,and the maximum decrease was 3.56% under 20 Gs.With the increase of magnetic field intensity,the active concentration under 60 Gs and 80 Gs magnetic field was higher than other magnetic field intensities,and the quality of frozen plasma was the best.