Search

Objective: In order to explore the effect of an external electrostatic field on the growth of ice crystals during food freezing. Methods: Based on the classic Kobayashi model of phase field method, the free energy density of electric field was introduced into the phase field model. Used the five-point difference scheme in the finite difference method to discretize the partial differential equation, the simulation and visualization of ice crystal growth were realized by programming. Results: The results showed that the simulation results were consistent with other simulation results and experimental results, and the ice crystal morphology had a typical sixfold symmetry; With the increase of electric field intensity, the growth rate of main branches and nucleation growth of ice crystals were inhibited. Conclusion: In the process of quick-frozen food preservation, adding a certain electric field strength will reduce the formation of ice crystals, and retain the quality and flavor of food as much as possible.

Objective: To explore metabolite profiling changes in serum of rats with pi-qi deficiency syndrome (PQDS) and pi-yang deficiency syndrome (PYDS) based on liquid chromatograph-mass spectrometer (LC-MS) technique, and to explore the essence of Pi-deficiency syndrome (PDS) from small molecule metabolite level., Methods: Totally 21 male SD rats of SPF grade were randomly divided into three groups, the normal control group, the PQDS group, and the PYDS group, 7 in each group. Rats in the PQDS group overate for 1 day and fasted for 2 days. They drank freely and then swam to be exhausted in water at 35 degrees C - 37 degrees C for 15 successive days. The PYDS model was established by the same method for PQDS rats plus drenching 20% Folium sennae water extract (2 mL/100 g), once in the morning and once in the evening for one successive week. After modeling, models were evaluated according to rat general state, changes in body weight and rectal temperature. Serum metabonomic profiles were detected using LC-MS technique. Difference in inter-group metabolite spectrograms was analyzed using orthogonal partial least squares discriminant analysis (OPLS-DA). Potential biomarkers related to syndrome types in rat serum were selected via the parameter of variable importance in the projection (VIP)., Results: The weight of rats in the PQDS group and the PYDS group decreased more significantly after modeling. The difference in prepost weight was statistically significant from that of the normal control group (P < 0.01). It was more obviously lowered in the PYDS group than in the PQDS group (P < 0.05). Compared with the normal control group, the rectal temperature of rats in the PYDS group and the PQDS group decreased (P < 0.05, P < 0.01). It decresed more in the PYDS group than in the PQDS group (P < 0.05, P < 0.01). Compared with the normal control group, levels of PC(19:0)/PE(22:0), PC(17:0)/PE(20:0), capric acid, oleic acid, stearic acid, succinic acid, fumaric acid, malic acid, glucose increased; arachidonic acid, linolenic acid, lauric acid, androsterone, 4-heptanone, dihydroxyacetonephosphate (DHAP) (6:0), and uridine decreased in the PYDS group and the PQDS group. Compared with the PQDS group, levels of PC(22:1), PC (22:6), PE (18:0)/PC (15:0), retinol, and deoxycytidine increased significantly in the PYDS group; PC (18:1), PC(19 :3), PC (20:3), PC (17:0)/PE (20:0), PC (19:1)/PE (22:1), PC (19:0)/PE (22:0), PC (17:1)/PE (20: 1), PC (16:1)/PE (19:1), cholic acid, hippuric acid, furoic acid, undecanedicarboxylic acid, palmitoleic acid, hydroxy stearic acid, eicosatrienoic acid, phenylalanine, tyrosine, glutamic acid, serine, carbamoyl aspartic acid, palmitoyl carnitine, tetradecanoyl carnitine, acetylcarnitine, and linoleylcarnitine decreased more significantly in the PYDS group., Conclusions: Comparative contents of various serum metabolites changed significantly in PQDS and PYQS model groups. Some potential small molecular biomarkers related to PDS were preliminarily identified. These results might provide some data reference for exploring scientific connotation and pathological mechanisms of PDS.