ABSTRACT
Polyethylene glycol is a synthetic, biodegradable, and water-soluble polyether. Owing to its good biological and material properties, polyethylene glycol shows promise in spinal cord tissue engineering applications. Although studies have examined repairing spinal cord injury with polyethylene glycol, these compelling findings have not been recently reviewed or evaluated as a whole. Thus, we herein review and summarize the findings of studies conducted both within and beyond China that have examined the repair of spinal cord injury using polyethylene glycol. The following summarizes the results of studies using polyethylene glycol alone as well as coupled with polymers or hydrogels: (1) polyethylene glycol as an adjustable biomolecule carrier resists nerve fiber degeneration, reduces the inflammatory response, inhibits vacuole and scar formation, and protects nerve membranes in the acute stage of spinal cord injury. (2) Polyethylene glycol-coupled polymers not only promote angiogenesis but also carry drugs or bioactive molecules to the injury site. Because such polymers cross both the blood-spinal cord and blood-brain barriers, they have been widely used as drug carriers. (3) Polyethylene glycol hydrogels have been used as supporting substrates for the growth of stem cells after injury, inducing cell migration, proliferation, and differentiation. Simultaneously, polyethylene glycol hydrogels isolate or reduce local glial scar invasion, promote and guide axonal regeneration, cross the transplanted area, and re-establish synaptic connections with target tissue, thereby promoting spinal cord repair. On the basis of the reviewed studies, we conclude that polyethylene glycol is a promising synthetic material for use in the repair of spinal cord injury.
ABSTRACT
Satellite platform vibrations make dispersive imaging spectrometer and objects generate relative movement in exposure time, which seriously affects the quality of spectral data. PHI was made as the model of dispersive spectrometer, the impact of pitch, roll, yaw and three-axis vibrations on spectral data were studied chiefly, and distorted spectral data cubes under various vibrations were simulated, then the general law of distortion spectral cube caused by satellite platform vibration was gained. The results show that the dispersive imaging spectrometer has high requirements for reduction of vibration amplitude. A small amplitude also can generate great influence on spectrum. The spectral data must be corrected and the vibration of satellite platform must be reduced to ensure the authenticity of spectrum.
ABSTRACT
During the spectral imaging course of interference imaging spectrometers, satellite platform's instability will bring serious impact on the imaging quality. Based on studying the degradation mechanism, a differential dynamic imaging simulation method is proposed here to simulate the process of spectral imaging degradation. And in this method, the mean ratio of doping is put forward, which combines the satellite motion parameters with the impacts on spectral imaging. And the quantitative relationship between them is deduced in detail With environmental resources satellite as an example, the degraded result is simulated, showing that the vibration affects the spectral imaging not only in the spatial resolution but also in spectrum, with the region of rich species having more serious influence. And through the simulation and analysis, the satellite attitudes' stability is requested accurately, below which the impacts of satellite vibration on spectral imaging should be significant and it's necessary to adopt corresponding compensation measures.
