Developments in Antibacterial Therapy: Focus on Physical Stimuli Approaches.

At present, various antibacterial therapeutic modalities are available in the clinic. However, due to the rampant abuse of antibiotics over the past few decades and the consequent emergence of innumerable drug-resistant strains of bacteria, it is imperative to develop new and effective antibacterial therapeutic strategies. In recent years, the physical stimuli-based approach to antibacterial therapy has aroused much interest as an alternative to antibiotics and has become a major focus of antibacterial research. In this review, the application of different physical stimuli, including electricity, magnetism, light, ultrasound and thermal stimulation, in antibacterial research is critically examined in order to provide new ideas and directions for the further development of antibacterial therapy in clinical dentistry.

Mechanical performance of polymer-infiltrated zirconia ceramics.

OBJECTIVE: The aim of this study was to evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of pre-sintering temperature (1000-1150°C). METHODS: Polymer-infiltrated zirconia ceramics were prepared by combining the porous zirconia networks and polymer through infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism were observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively. A nanoindentation system was employed to determine elastic modulus and hardness. RESULTS: Different porosities and polymer contents can be obtained by tuning the pre-sintered temperature of zirconia ceramic precursors. Zirconia network porosity varies from 46.3% to 34.7% and the relevant polymer content ranges from 18.4wt.% to 12.3wt.% when the pre-sintered temperature is set from 1000°C to 1150°C. The flexural strength, fracture toughness, hardness, and elastic modulus values of the specimen pre-sintered at 1150°C are 240.9MPa, 3.69MPam1/2, 3.1GPa, and 58.8GPa, respectively. CONCLUSION: The pre-sintering temperature has a significant effect on the microstructure and mechanical properties of polymer-infiltrated zirconia ceramics and the optimal pre-sintering temperature is 1150°C. CLINICAL SIGNIFICANCE: Specimen pre-sintered at 1150°C shows tooth-like mechanical properties, suggesting a promising restorative material in dental clinic. Moreover, the synthesis process is simple and can be easily performed in a prosthesis laboratory.

[Experiment study on carriers in moving bed biofilm reactor].

Two methods of mixture modified and corona discharge were used to modify hydrophilic performance of the surface of the carriers. By mixture modified, the contact angle reduced from 108 degrees to 88 degrees, which showed carriers were hydrophilic; corona discharge could strengthen the effect and contact angle could reduce to 72 degrees further, although the effect lasted short time. To compare two carriers modified by corona discharge or not, evaluation system for biological quality of carries were established from two aspects: monitor indexes and monitor methods. Experiment lasted for 20 days. The results showed that the reactor filled with the former started up more quickly. On the 2nd day, removal rate of COD and NH4(+) -N was 80% and 97%, respectively; while removal rate of the reactor filled with the latter only reached 61% and 63%, respectively. But soon, the removal rate of the both pollutants was nearly the same. It confirmed that the modified effect by corona discharge lasted short time, and indicated this evaluation system was fast, feasible and reliable.