Experimental and Numerical Evaluation of the Cavitation Performances of Self-Excited Oscillating Jets

Self-excited oscillating jets(SOJ)are used in several practical applications.Their performances are significantly affected by structural parameters and the target distance.In this study,a geometric model of the SOJ nozzle accounting for multiple structural parameters is introduced,then the related cavitation performances and the optimal target distance are investigated using a Large-Eddy Simulation(LES)approach.Results are also provided about an experiment,which was conducted to validate the simulation results.By analyzing the evolution of the vapor volume fraction at the nozzle outlet,a discussion is presented about the effect of the aforementioned structural parameters on the cavitation performances and the target distance.It is shown that the distribution of cavitation clouds at the outlet of the SOJ nozzle displays a non-monotonic trend(first increasing,then decreasing).Under working conditions with an inlet pressure of 4 MPa,a SOJ nozzle outlet/inlet diameter ratio(D_(1)/D_(2))of 1.2,and a chamber diameter ratio(D/L)close to 1.8,the nozzle outlet cavitation performance attains a maximum.The optimal structural parameters correspond to the optimal target distance,which is near 50 mm.The experiments have revealed that the SOJ nozzle with the above parameters displays a good cavitation erosion effect at the target distance of 50 mm,in satisfactory agreement with the numerical simulation results.

A bioactive glass functional hydrogel enhances bone augmentation via synergistic angiogenesis,self-swelling and osteogenesis

Bone augmentation materials usually cannot provide enough new bone for dental implants due to the material degradation and mucosal pressure.The use of hydrogels with self-swelling properties may provide a higher bone augmentation,although swelling is generally considered to be a disadvantage in tissue engineering.Herein,a double-crosslinked gelatin-hyaluronic acid hydrogels(GH)with self-swelling properties were utilized.Meanwhile,niobium doped bioactive glasses(NbBG)was dispersed in the hydrogel network to prepare the GH-NbBG hydrogel.The composite hydrogel exhibited excellent biocompatibility and the addition of NbBG significantly improved the mechanical properties of the hydrogel.In vivo results found that GH-NbBG synergistically promoted angiogenesis and increased bone augmentation by self-swelling at the early stage of implantation.In addition,at the late stage after implantation,GH-NbBG significantly promoted new bone formation by activating RUNX2/Bglap signaling pathway.Therefore,this study reverses the self-swelling disadvantage of hydrogels into advantage and provides novel ideas for the application of hydrogels in bone augmentation.

Bioactive glass promotes the barrier functional behaviors of keratinocytes and improves the Re-epithelialization in wound healing in diabetic rats

Upon skin injury,re-epithelialization must be triggered promptly to restore the integrity and barrier function of the epidermis.However,this process is often delayed or interrupted in chronic wounds like diabetic foot ulcers.Considering that BG particles can activate multiple genes in various cells,herein,we hypothesized that bioactive glass(BG)might be able to modulate the barrier functional behaviors of keratinocytes.By measuring the transepithelial electrical resistance(TEER)and the paracellular tracer flux,we found the 58S-BG extracts substantially enhanced the barrier function of keratinocyte monolayers.The BG extracts might exert such effects by promoting the keratinocyte differentiation and the formation of tight junctions,as evidenced by the increased expression of critical differentiation markers(K10 and involucrin)and TJ protein claudin-1,as well as the altered subcellular location of four major TJ proteins(claudin-1,occludin,JAM-A,and ZO-1).Besides,the cell scratch assay showed that BG extracts induced the collective migration of keratinocytes,though they did not accelerate the migration rate compared to the control.The in vivo study using a diabetic rat wound model demonstrated that the BG extracts accelerated the process of re-epithelialization,stimulated keratinocyte differentiation,and promoted the formation of tight junctions in the newly regenerated epidermis.Our findings revealed the crucial effects of BGs on keratinocytes and highlighted its potential application for chronic wound healing by restoring the barrier function of the wounded skin effectively.

Strontium-substituted sub-micron bioactive glasses inhibit ostoclastogenesis through suppression of RANKL-induced signaling pathway

Strontium-substituted bioactive glass(Sr-BG)has shown superior performance in bone regeneration.Sr-BG-induced osteogenesis has been extensively studied;however,Sr-BG-mediated osteoclastogenesis and the underlying molecular mechanism remain unclear.It is recognized that the balance of osteogenesis and osteoclastogenesis is closely related to bone repair,and the receptor activators of nuclear factor kappaB ligand(RANKL)signaling pathway plays a key role of in the regulation of osteoclastogenesis.Herein,we studied the potential impact and underling mechanism of strontium-substituted sub-micron bioactive glass(Sr-SBG)on RANKL-induced osteoclast activation and differentiation in vitro.As expected,Sr-SBG inhibited RANKL-mediated osteoclastogenesis significantly with the experimental performance of decreased mature osteoclasts formation and downregulation of osteoclastogenesis-related gene expression.Furthermore,it was found that Sr-SBG might suppress osteoclastogenesis by the combined effect of strontium and silicon released through inhibition of RANKL-induced activation of p38 and NF-κB pathway.These results elaborated the effect of Sr-SBG-based materials on osteoclastogenesis through RANKLinduced downstream pathway and might represent a significant guidance for designing better bone repair materials.

Design and evaluation of a novel sub-scaffold dental implant system based on the osteoinduction of micro-nano bioactive glass

Alveolar ridge atrophy brings great challenges for endosteal implantation due to the lack of adequate vertical bone mass to hold the implants.To overcome this limitation,we developed a novel dental implant design:sub-scaffold dental implant system(SDIS),which is composed of a metal implant and a micro-nano bioactive glass scaffold.This implant system can be directly implanted under mucous membranes without adding any biomolecules or destroying the alveolar ridge.To evaluate the performance of the novel implant system in vivo,SDISs were implanted into the subepicranial aponeurosis space of Sprague–Dawley rats.After 6 weeks,the SDIS and surrounding tissues were collected and analysed by micro-CT,scanning electron microscopy and histology.Our results showed that SDISs implanted into the sub-epicranial aponeurosis had integrated with the skull without any mobility and could stably support a denture.Moreover,this design achieved alveolar ridge augmentation,as active osteogenesis could be observed outside the cortical bone.Considering that the microenvironment of the sub-epicranial aponeurosis space is similar to that of the alveolar ridge,SDISs have great potential for clinical applications in the treatment of atrophic alveolar ridges.The study was approved by the Animal Care Committee of Guangdong Pharmaceutical University(approval No.2017370).