OBJECTIVE To investigate the effects of different sterilization methods on 3D-printed polylactic acid(PLA)guide plates for orthopedic surgery,and to analyze their physical properties,microbial contamination,structural performance and bio compatibility after sterilization.METHODS PLA guide plates for orthopedic surgery were prepared with 3D printing technology and divided into a blank group,a hydrogen peroxide plasma steriliza-tion group,an ethylene oxide sterilization group and a pressure steam sterilization group.Before and after sterili-zation,the changes in volume and weight of the surgical guide plates were measured,microbial detection was con-ducted,structural changes were observed with a laser scanning confocal microscope,and cell co-culture was con-ducted to evaluate biocompatibility,thereby the effects of different sterilization methods were assessed.RESULTS The three sterilization methods had no significant effect on the volume and weight of PLA surgical guide plates.Microbial detection showed that all three sterilization methods were effective in killing bacteria,and bacte-rial cultures were negative.Laser confocal scanning microscopy revealed that sterilization treatment caused certain changes to the microstructure of the surgical guide plates,but high-temperature sterilization had a more pro-nounced effect on the deformation of the guide plate edges.Cell co-culture results indicated that the surgical guide plates treated with the three sterilization methods exhibited acceptable cytotoxicity and had little effect on cell pro-liferation.CONCLUSIONS All three sterilization methods cause microstructural changes to the surgical guide plate.Among them,pressure steam sterilization significantly deforms the structure of the guide plate,directly af-fecting its precise positioning of mutual spatial distances,angular relationships and orientation during surgery.Al-though hydrogen peroxide plasma sterilization does not cause significant deformation,ethylene oxide sterilization has the least impact on material properties and structural stability while ensuring the sterilization effect of PLA surgical guide plates.

OBJECTIVE To investigate the effects of different sterilization methods on 3D-printed polylactic acid(PLA)guide plates for orthopedic surgery,and to analyze their physical properties,microbial contamination,structural performance and bio compatibility after sterilization.METHODS PLA guide plates for orthopedic surgery were prepared with 3D printing technology and divided into a blank group,a hydrogen peroxide plasma steriliza-tion group,an ethylene oxide sterilization group and a pressure steam sterilization group.Before and after sterili-zation,the changes in volume and weight of the surgical guide plates were measured,microbial detection was con-ducted,structural changes were observed with a laser scanning confocal microscope,and cell co-culture was con-ducted to evaluate biocompatibility,thereby the effects of different sterilization methods were assessed.RESULTS The three sterilization methods had no significant effect on the volume and weight of PLA surgical guide plates.Microbial detection showed that all three sterilization methods were effective in killing bacteria,and bacte-rial cultures were negative.Laser confocal scanning microscopy revealed that sterilization treatment caused certain changes to the microstructure of the surgical guide plates,but high-temperature sterilization had a more pro-nounced effect on the deformation of the guide plate edges.Cell co-culture results indicated that the surgical guide plates treated with the three sterilization methods exhibited acceptable cytotoxicity and had little effect on cell pro-liferation.CONCLUSIONS All three sterilization methods cause microstructural changes to the surgical guide plate.Among them,pressure steam sterilization significantly deforms the structure of the guide plate,directly af-fecting its precise positioning of mutual spatial distances,angular relationships and orientation during surgery.Al-though hydrogen peroxide plasma sterilization does not cause significant deformation,ethylene oxide sterilization has the least impact on material properties and structural stability while ensuring the sterilization effect of PLA surgical guide plates.

Objective:To investigate the intelligence status of children aged 10 - 12 in rural areas of Linxia Hui Autonomous Prefecture (referred to as Linxia) in Gansu Province.Methods:From September to November 2019, a cross-sectional study was carried out to investigate the intelligence status of children aged 10 to 12 in 8 counties (cities) of Linxia. Chinese Raven's Progressive Matrices (rural version) was used for intelligence test and children's intelligence quotient (IQ) was calculated by regular mold to evaluate children's intelligence level.Results:A total of 1 721 children in Linxia were tested for intelligence, with an average IQ of 103.2. Among them, low intelligence (≤69) accounted for 1.0% (18/1 721), borderline (70 - 79) accounted for 3.0% (52/1 721), middle and lower (80 - 89) accounted for 8.4% (144/1 721), moderate (90 - 109) accounted for 56.6% (974/1 721), middle and upper (110 - 119) accounted for 21.9% (377/1 721), excellent (120 - 129) accounted for 7.8% (135/1 721), extremely excellent (≥130) accounted for 1.2% (21/1 721). There were 635, 598 and 488 children aged 10, 11 and 12, respectively, with an average IQ of 106.1, 103.3 and 99.2. There were 919 males and 802 females, with an average IQ of 102.9 and 103.4, respectively.Conclusion:In 2019, the intelligence of children aged 10 to 12 in rural areas of Linxia has reached the moderate level.