Injection molding of ultra-fine Si_3N_4 powder for gas-pressure sintering

The ceramic injection molding technique was used in the gas-pressure sintering of ultra-fine Si3N4 powder. The feedstock＇s flowability, debinding rate, defect evolution, and microstructural evolution during production were explored. The results show that the solid volume loading of less than 50vol% and the surfactant mass fraction of 6wt% result in a perfect flowability of feedstock; this feedstock is suitable for injection molding. When the debinding time is 8 h at 40°C, approximately 50% of the wax can be solvent debinded. Defects detected during the preparation are traced to improper injection parameters, mold design, debinding parameters, residual stress, or inhomogeneous composition distribution in the green body. The bulk density, Vickers hardness, and fracture toughness of the gas-pressure-sintered Si3N4 ceramic reach 3.2 g/cm^3, 16.5 GPa, and 7.2 MPa·m^1/2, respectively.

Advanced Hydrogel systems for mandibular reconstruction

Mandibular defect becomes a prevalent maxillofacial disease resulting in mandibular dysfunctions and huge psychological burdens to the patients.Considering the routine presence of oral contaminations and aesthetic restoration of facial structures,the current clinical treatments are however limited,incapable to reconstruct the structural integrity and regeneration,spurring the need for cost-effective mandibular tissue engineering.Hydrogel systems possess great merit for mandibular reconstruction with precise involvement of cells and bioactive factors.In this review,current clinical treatments and distinct mode(s)of mandible formation and pathological resorption are summarized,followed by a review of hydrogel-related mandibular tissue engineering,and an update on the advanced fabrication of hydrogels with improved mechanical property,antibacterial ability,injectable form,and 3D bioprinted hydrogel constructs.The exploration of advanced hydrogel systems will lay down a solid foundation for a bright future with more biocompatible,effective,and personalized treatment in mandibular reconstruction.

A review of hydrogels used in endoscopic submucosal dissection for intraoperative submucosal cushions and postoperative management

Endoscopic submucosal dissection(ESD)has been clinically proved to have prominent advantages in the treatment of early gastrointestinal cancers over traditional surgery,including less trauma,fewer complications,a quicker recovery and lower costs.During the procedure of ESD,appropriate and multifunctional submucosal injected materials(SIMs)as submucosal cushions play an important role,however,even with many advances in design strategies of SIMs over the past decades,the performance of the submucosal cushions with postoperative management function seems to be still unsatisfactory.In this review,we gave a brief historical recount about the clinical development of SIMs,then some common applications of hydrogels used as SIMs in ESD were summarized,while an account of the universal challenges during ESD procedure was also outlined.Going one step further,some cutting-edge functional strategies of hydrogels for novel applications in ESD were exhibited.Finally,we concluded the advantages of hydrogels as SIMs for ESD as well as the treatment dilemma clinicians faced when it comes to deeply infiltrated lesions,some technical perspectives about linking the clinical demand with commercial supply were also proposed.Encompassing the basic elements of SIMs used in ESD surgery and the corresponding postoperative management requirements,this review could be a good reference for relevant practitioners in expanding the research horizon and improving the well-being index of patients.