Effect of temperature and humidity on mechanical properties and constitutive modeling of pressure-sensitive adhesives.

Pressure-sensitive adhesives (PSAs) are crucial for the structural and functional integrity of flexible displays. Investigating the intricate mechanical properties of PSAs can help enhance product quality and performance. This study conducts systematic mechanical tests, including uniaxial tensile, compression, planar shear, and stress relaxation, on PSAs at temperatures ranging from - 25 to 85 â„ƒ and relative humidity levels from 0 to 90%. Our findings reveal that the Anssari-Benam model accurately describes the hyperelastic behavior of PSA materials under large deformation, outperforming the Ogden model by requiring fewer parameters and better preserving convexity. Moreover the results show that temperature markedly affects PSA properties, particularly near the glass transition temperature (Tg), with lower temperatures leading to decreased elasticity and higher temperatures aiding in stress relaxation. Similarly, humidity impacts PSA behavior, increasing elasticity and decreasing stiffness, especially noticeable in stress relaxation tests. These findings highlight the substantial influence of environmental conditions on the material properties of PSAs and underscore the necessity of understanding both hyperelastic and viscoelastic responses for their application in flexible technologies. This research provides critical insights for the optimal utilization of PSAs in the rapidly evolving field of flexible electronics, including OLED displays.

Protocol for modeling and simulating lithiation-induced stress in largely deformed spherical nanoparticles using COMSOL.

Here, we present a finite element method-based scheme for solving coupled partial differential equations (PDEs) for the analysis of lithiation-induced stress in largely deformed spherical nanoparticles via the PDE module in COMSOL. We describe steps for software installation and setting PDEs, initial/boundary conditions, and mesh parameters. We then detail procedures for dividing the mesh and analyzing lithium trapping during electrochemical cycling. This protocol can also be extended to analyze a wide range of problems involving diffusion-induced stress. For complete details on the use and execution of this protocol, please refer to Li et al.1.

[Surgical approach of internal fixation of maxillofacial fracture].

OBJECTIVE: By summary and analysis of rigid internal fixation for the treatment of maxillofacial fractures incision and exposure, investigate the plate reasonable surgical approach of fracture reduction and fixation titanium. METHOD: Summary of the 76 surgical cases, Counting the statistics of the number that the surgery ways choose by facial incision and fractures location, analysis of the indications for surgery and the advantages and disadvantages of various surgical approaches. Followed up for more than six months, in order to observe the recovery of occlusal function and the facial cosmetic results. RESULT: The upper jaw or cheek bone has the more possibility in facial fracture, which used of a small incision hidden under the lip gingival sulcus and lower eyelid. After six months, the facial wound healing recover in good occlusal with no obvious scarring. CONCLUSION: Reasonable choice of surgical incision can make the fracture site exposure and the facial aesthetic effect into account.

Construction of tissue-engineered cartilage using human placenta-derived stem cells.

Human placenta-derived stem cells (hPDSCs) were isolated by trypsinization and further induced into cartilage cells in vitro. The engineered cartilage was constructed by combining hPDSCs with collagen sponge and the cartilage formation was observed by implantation into nude mice. Results showed that hPDSCs featured mesenchymal stem cells and maintained proliferation in vitro for over 30 passages while remaining undifferentiated. All results indicated that hPDSCs have the potential to differentiate into functional cartilage cells in vitro when combined with collagen sponge, which provided experimental evidence for prospective clinical application.