No abstract

No abstract

No abstract

Observing the structure and regeneration of the myelin sheath in peripheral nerves following injury and during repair would help in understanding the pathogenesis and treatment of neurological diseases caused by an abnormal myelin sheath. In the present study, transmission electron microscopy, immunofluorescence staining, and transcriptome analyses were used to investigate the structure and regeneration of the myelin sheath after end-to-end anastomosis, autologous nerve transplantation, and nerve tube transplantation in a rat model of sciatic nerve injury, with normal optic nerve, oculomotor nerve, sciatic nerve, and Schwann cells used as controls. The results suggested that the double-bilayer was the structural unit that constituted the myelin sheath. The major feature during regeneration was the compaction of the myelin sheath, wherein the distance between the 2 layers of cell membrane in the double-bilayer became shorter and the adjacent double-bilayers tightly closed together and formed the major dense line. The expression level of myelin basic protein was positively correlated with the formation of the major dense line, and the compacted myelin sheath could not be formed without the anchoring of the lipophilin particles to the myelin sheath.

Sandwich structures are important innovative multifunctional structures with the advantages of low density and high performance. Creative design for sandwich structures is a design process based on sandwich core structure evolution mechanisms, material design method, and panel (including core structure and facing sheets) performance prediction model. The review outlines recent research efforts on creative design for sandwich structures with different core constructions such as corrugated core, honeycomb core, foam core, truss core, and folded cores. The topics discussed in this review article include aspects of sandwich core structure design, material design, and mechanical properties, and panel performance and damage. In addition, examples of engineering applications of sandwich structures are discussed. Further research directions and potential applications are summarized.

4D printing deforms a 2D foldable structure to another shape evolve over time by using heterogeneous material. The deformation of the 2D foldable structure is stimulated by actuators that are fabricated by shape memory materials or bilayer structures. Therefore, the deformation programming method of actuators is a critical technology in 4D printing. This paper proposes a method for programming the deformation of a temperature-driven bilayer structure actuator in 4D printing. The thermo-mechanical mechanism of the bilayer structure actuator is analyzed and three kinds of deformation behavior are modeled. Then a constitutive model with five main deformation programming parameters including the line width, the print height, the print temperature, the filled form, and the stimulation temperature is fitted by the orthogonal experiment and response surface method. The permanent deformation of the bilayer structure actuator results from the programmed parameters and time evolution of the 3D printed structure upon heating. A typical temperature shape memory material polylactic acid is used as a case study to illustrate the methodology and a desired programmed deformation is achieved.

No abstract

No abstract