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为提高蛋白基Pickering乳液稳定性，采用美拉德反应制备乳清分离蛋白（WPI）-葡聚糖（Dex）接枝物，然后利用该接枝物制得蛋白基固体颗粒，再与中链甘油三酯制备Pickering乳液，考察WPI-Dex接枝物对蛋白基固体颗粒乳化活性、乳化稳定性和蛋白基Pickering乳液乳析指数的影响，以及Pickering乳液在不同pH、加热温度、贮藏时间下粒径的变化。结果表明：扫描电镜观察到共价接枝Dex将WPI形貌结构由球状转变为片状，十二烷基硫酸钠-聚丙烯酰胺凝胶电泳证实干法美拉德反应成功制备了WPI-Dex接枝物；与WPI相比，WPI-Dex接枝物的乳化活性和乳化稳定性分别增加了57.8%和138.5%；WPI和WPI-Dex接枝物Pickering乳液贮藏30 d时的乳析指数分别为52.3%和36.0%，WPI-Dex接枝物使Pickering乳液的乳析稳定性提高了31.2%；WPI-Dex接枝物Pickering乳液具有良好的pH稳定性、热稳定性和贮藏稳定性。综上，蛋白质糖基化接枝修饰是提高天然蛋白质Pickering乳液稳定性的有效方法。In order to improve the stability of protein-based Pickering emulsion, Maillard reaction was used to prepare the whey protein isolate(WPI)-dextran(Dex) conjugate. The WPI-Dex conjugate was used to prepare protein-based solid particles, and then Pickering emulsion was prepared with medium-chain triglyceride. The effects of the WPI-Dex conjugate on the emulsification activity, emulsion stability of protein-base solid particles and creaming index of Pickering emulsion were investigated, as well as the change of diameter of Pickering emulsion under different pH, heating temperature and storage time. The results showed that scanning electron microscopy (SEM) observed the covalently grafted Dex transformed the morphologic structure of WPI from globular to flake. The WPI-Dex conjugate was successfully prepared by the dry state Maillard reaction, which was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Compared with WPI, the emulsification activity and emulsion stability of WPI-Dex conjugate increased by 57.8% and 138.5%, respectively. The creaming indexes of WPI and WPI-Dex conjugate Pickering emulsion stored for 30 d were 52.3% and 36.0%, respectively, and the creaming stability of WPI-Dex conjugate Pickering emulsion increased by 31.2%. WPI-Dex conjugate Pickering emulsion had good pH stability, thermal stability and storage stability. In conclusion, the glycosylation graft modification of protein is an effective method to improve the stability of natural protein Pickering emulsions.

The locking mechanism between bracket and shape memory alloy (SMA) archwire in the newly developed domestic orthodontic device is the key to controlling the precise alignment of the teeth. To meet the demand of locking force in clinical treatment, the tightening torque angle of the locking bolt and the required torque magnitude need to be precisely designed. For this purpose, a design study of the locking mechanism is carried out to analyze the correspondence between the tightening torque angle and the locking force and to determine the effective torque value, which involves complex coupling of contact, material and geometric nonlinear characteristics. Firstly, a simulation analysis based on parametric orthogonal experimental design is carried out to determine the SMA hyperelastic material parameters for the experimental data of SMA archwire with three-point bending. Secondly, a two-stage fine finite-element simulation model for bolt tightening and archwire pulling is established, and the nonlinear analysis is converged through the optimization of key contact parameters. Finally, multiple sets of calibration experiments are carried out for three tightening torsion angles. The comparison results between the design analysis and the calibration experiments show that the deviation between the design analysis and the calibration mean value of the locking force in each case is within 10%, and the design analysis method is valid and reliable. The final tightening torque angle for clinical application is determined to be 10° and the rated torque is 2.8 N∙mm. The key data obtained can be used in the design of clinical protocols and subsequent mechanical optimization of novel orthodontic devices, and the research methodology can provide a valuable reference for force analysis of medical devices containing SMA materials.

Induced pluripotent stem cells (iPSCs) are obtained by introducing exogenous genes or adding chemicals to the culture medium to induce somatic cell differentiation. Similarly to embryonic stem cells, iPSCs have the ability to differentiate into all three embryonic cell lines. iPSCs can differentiate into cardiac muscle cells through two-dimensional differentiation methods such as monolayer cell culture and co-culture, or through embryoid body and scaffold-based three-dimensional differentiation methods. In addition, the process of iPSCs differentiation into cardiac muscle cells also requires activation or inhibition of specific signaling pathways,such as Wnt, BMP, Notch signaling pathways to mimic the development of the heart in vivo . In recent years, suspension culturing in bioreactors has been shown to produce large number of iPSCs derived cardiac muscle cells (iPSC-CMs). Before transplantation, it is necessary to purify iPSC-CMs through metabolic regulation or cell sorting to eliminate undifferentiated iPSCs, which may lead to teratoma formation. The transplantation methods for iPSC-CMs are mainly injection of cell suspension and transplantation of cell patches into the infarcted myocardium. Animal studies have shown that transplantation of iPSC-CMs into the infarcted myocardium can improve cardiac function. This article reviews the progress in preclinical studies on iPSC-CMs therapy for acute myocardial infarction and discusses the limitations and challenges of its clinical application to provide references for further clinical research and application.

In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.