Chunming Wang

The use of fully premixed combustion in small gas boilers can improve denitrification efficiency. On the basis of fully premixed combustion, adding flame stabilizers inside the boiler can further reduce production of oxides of nitrogen. Four types of flame-stabilizing baffles were added at a certain position inside the furnace after the fully premixed burner. Experiments were conducted separately on the Noporous baffle, and numerical calculations were performed for 36 operating conditions of the four baffles. The experimental results and numerical calculations indicate that under experimental conditions, NO_x emissions were all below 40 mg/m³, and the net heat efficiency of the boiler was above 80%. Under a maximum firing rate, CO emissions are below 20 ppm, and the minimum error between the calculated and experimental values is 2.2%. The calculation error of CO emissions under various working conditions does not exceed 6.8%, indicating that the impact of different-shaped baffles on CO emissions is relatively small. When installing a Nonporous baffle, the error between the experimental and calculated exhaust temperature values under minimum firing rates is 6.6%, the error between the calculated and measured values under middle firing conditions is 2.9%, and the error between the calculated and measured values under maximum firing rate conditions is 3.0%. Among the four different partition conditions, the exhaust temperature of the Nonporous baffle is the lowest. Under the same excess air coefficient, the pressure in the furnace for the middle and maximum firing rate is higher than that of the minimum firing rate, and the experimental values are in good agreement with the calculated values. When installing the Strip baffle, the calculated CO₂ emission is the lowest. The experimental results show that the NO_x in the flue gas inside the furnace is mainly NO, and the NO content exceeds 75%, reaching a maximum of 85%. The experimental results show that the minimum NO_x emission value is 26.9 mg/m³. The error between the measured and calculated NO_x values when installing a Nonporous baffle is 20.4%. All of the above indicate that installing a flame-stabilizing baffle at an appropriate position in the furnace can further reduce NO_x emissions, and the optimization amplitude is related to the shape of the baffle.

Photodynamic therapy (PDT) is a widely used therapeutic approach for eradicating bacterial biofilms in infected wound, but its effectiveness is limited by the hypoxic environment within the biofilm. This study aimed to investigate whether the efficiency of photodynamic removing biofilm is improving by providing oxygen (O₂), as well as the expression of cytokines involved in infected wound healing. Manganese dioxide (MnO₂) nanoparticles with catalase-like activity were grown in situ on graphitic phase carbon nitride (g-C₃N₄, CN) nanosheets to construct an all-in-one CN-MnO₂ nanozyme, which was then incorporated into poly-L-lactic acid (PLLA) to prepare CN-MnO₂/PLLA wound dressing by electrospinning. Subsequently, the in vitro antibacterial biofilm ratio and antibacterial ratio of CN-MnO₂/PLLA wound dressing were examined by spread plate and crystal violet staining under irradiation with 808 nm near-infrared light and 660 nm visible light. Meanwhile, the rat skin injury model was established, and hematoxylin and eosin (H&E), Masson’s, tumor necrosis factor-α (TNF-α), Arginase 1 (Arg-1), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (BFGF) were evaluated in vivo to assess the effect of CN-MnO₂/PLLA wound dressing on wound healing. Biofilm density caused by Staphylococcus aureus and Pseudomonas aeruginosa had elimination rates of 83 and 62%, respectively, when treated with CN-MnO₂/PLLA dressing. Additionally, the dressing exhibited high antibacterial efficacy against both bacteria, achieving 99 and 98.7% elimination of Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Furthermore, in vivo experiments showed that the CN-MnO₂/PLLA wound dressing achieved complete healing of infected wounds on Day 14, with a wound healing rate of >99% by increasing collagen deposition, expression of anti-inflammatory cytokine Arg-1, vascularization cytokine VEGF, and epithelial cell BFGF, and inhibiting the expression of inflammatory cytokine TNF-α. The CN-MnO₂/PLLA wound dressing exhibited excellent antibacterial properties in vitro and in vivo. In addition, CN-MnO₂/PLLA wound dressing accelerated rapid wound healing through an anti-inflammatory, pro-vascular regeneration and skin tissue remodeling mechanism.

The nanograins (NG) on the top surface layer of alloy 690 were successfully prepared by ultrasonic surface rolling treatment (USRT). The average grain size of NG alloy 690 was 55 nm, and the thickness of the NG surface layer was about 1 μm. Meanwhile, the surface roughness was significantly reduced after surface nanocrystalliztion. The corrosion behavior of alloy 690 before and after USRT was studied in a secondary side environment containing chloride. Electrochemical corrosion experiments demonstrated that the passive film generated by USRT was denser than that formed on coarse-grained (CG) alloy 690. Pitting corrosion was prone to occur in grain boundaries of CG alloy 690, and the pits on the surface of NG alloy 690 were smaller than those generated on CG alloy 690 after 1000 h of an immersion experiment.