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This paper proposes a new analytical model to predict plastic deformation and strain distributions in aluminium-alloy plates under low velocity impact loading. The low velocity impact load on the fully clamped circular plate was idealized as a quasi-static normal point force acting at the centre of plate. Based on apt geometrical approximation and assumptions, governing equations were established to predict the out-of-plane deflection and the radial tensile, radial and circumferential flexure strains in fully clamped conditions. From the deformation theory of plasticity, a new formula was derived to estimate the impact load by incorporating strain-energy approach, bilinear strain-hardening constitutive model and the one-dimensional Tresca yield criterion. Low velocity impact tests were performed to confirm the proposed model and good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed model. [ABSTRACT FROM AUTHOR]

Objective: To investigate the feasibility and effect of human amniotic membrane in prevention of tendon adhension after tendon sheat defect repair., Methods: The amniotic membrane in size of 1.5 cm x 1.0 cm was harvested from human placenta which was voluntary donated from maternal after cesarean. Forty healthy male Leghorn chicken (aged 3-6 months) were selected, weighing (1.86 +/- 0.04) kg. The model of flexor digitorum profundus tendon and tendon sheath defects was established at the third toe. After repair of the flexor digitorum profundus tendon, the human amniotic membrane was used to repair the tendon sheath defect in the right foot (group A), but tendon sheath defect was not repaired in the left foot (group B) . At 1, 2, 4, and 6 weeks after operation, the gross and histological observations were done; the degree of tendon adhesions was graded according to Tang's tendon adhesion general observation grading standards; and the biomechanical properties (tendon slip length and total flexion angle) were tested., Results: All animals survived after operation and incisions healed. Gross and histological observations showed that the new tendon sheath formed with time passing after operation in groups A and B; new tendon sheath was more maturer and smoother in group A than in group B. The degree of tendon adhesions in group A was significantly less than that in group B (P < 0.05) at 1 and 6 weeks after operation. The biomechanical test results showed there was no significant difference in the tendon slip length between 2 groups at 1 and 2 weeks after operation (P > 0.05), but the tendon slip length of group A was significantly longer than that of group B at 4 and 6 weeks after operation (P < 0.05). The total flexion angle of group A was significantly smaller than that of group B at 1, 2, 4, and 6 weeks after operation (P < 0.05)., Conclusion: It is effective in the prevention of tendon adhesion to use the amniotic membrane for repairing the tendon sheath defect, which is beneficial to recovery of the tendon sliding function.

Objective: Triptolide can suppress immunological rejection reaction. To investigate the effect of triptolide on allogenic tendon transplantation in repairing tendon defect in chicken., Methods: The defect model of the third toes tendon was established in 64 healthy-cleaning male Leghorn chickens (4-month-old, weighing 1.9-2.3 kg), which underwent allogenic tendon transplantation for repairing and were divided into 2 groups randomly (n=32). Triptolide feeding [100 microg/(kg x d)] was given for 3 weeks in the experimental group and normal feeding in the control group. General condition of the chickens was observed after operation. The transplanted tendons were harvested from 4 chickens in each group for gross observation at 1, 2, 3, and 4 weeks after operation; the histological observation was performed at 1 and 3 weeks, and transmission electron microscope observation at 2 and 4 weeks. The blood and tendon were harvested from another 8 chickens in each group for flow cytometry and biomechanical tests respectively at 3 and 6 weeks., Results: All chickens survived to the experiment end. Gross observation: with time extending, hyperemia and edema around transplanted tendon were relieved. Rarefaction adhering zone was seen in experimental group, and pyknotic adhering zone in control group. Histological observation: inflammatory reaction in experimental group was slighter than that in control group at 1 and 3 weeks. Transmission electron microscope observation: at 2 and 4 weeks, fibroblasts had big cell nucleus, more euchromatin, and little heterochromatin in experimental group; however, there were small amount of rough endocytoplasmic reticulums with gentle expanded capsular space in control group, which contained sparse content. Flow cytometry test: at 3 and 6 weeks, peripheral blood contained less CD4+ and CD8+ T lymphocytes in experimental group than in control group, and the ratio of CD4+ to CD8+ T lymphocyte significantly decreased in experimental group when compared with control group (P < 0.05). Biomechanical examination: at 3 and 6 weeks, the maximum tensile strength in experimental group was bigger than that in control group, and tensile adhesion power in experimental group was smaller than that in control group. There were significant differences in the indexes between 2 groups (P < 0.05)., Conclusion: Triptolide can suppress immunological rejection reaction, strengthen tendon healing strength, and reduce tendon adhesion in allogenic tendon transplantation.