Polyether ether ketone(PEEK)-based continuous glass fiber reinforced thermoplastic composite offers advantages such as high strength,electrical insulation,and heat insulation.Parts manufactured using this composite an...Polyether ether ketone(PEEK)-based continuous glass fiber reinforced thermoplastic composite offers advantages such as high strength,electrical insulation,and heat insulation.Parts manufactured using this composite and 3D printing have promising applications in aerospace,automobile,rail transit,etc.In this paper,a high-temperature melt impregnation method was used to successfully prepare the 3D printing prepreg filaments of the aforementioned composite.In the FDM 3D printing equipment,a nozzle of high thermal conductivity and wear-resistant copper alloy and a PEEK-based carbon fiber thermoplastic composite build plate with uniform temperature control were innovatively introduced to effectively improve the quality of 3D printing.The porosity of the 3D printed samples produced from the composite prepreg filament was analyzed under different printing parameters,and the mechanical properties and fracture mechanism of the printed parts were studied.The results show that the printing layer thickness,printing speed,printing temperature and build plate temperature have varying effects on the porosity of printed parts,which in turn affects tensile strength and the interlaminar shear strength(ILSS).When the printing layer thickness is 0.4 mm,printing speed is 2 mm/s,nozzle temperature is 430℃ and build plate temperature is 150℃,the tensile strength and ILSS of the composite printed parts reach their maximum values of 463.76 and 24.95 MPa,respectively.Microscopic analysis of the fracture morphology of the tensile specimens reveals that the 3D printed CGF/PEEK composite sample has three types of fracture mode,which are single filament bundle fracture,fracture mode of delamination,and fracture failure of the sample at the cross-section.The essence of the above three kinds of fracture mode is the difference of the interface bonding force of 3D printed CGF/PEEK composites.The fracture failure at the cross-section is that the continuous glass fibers in the composite are pulled out until they break,which is the main form of the failure of the composite under tensile load.The interfacial region of the composite is prone to microscopic defects such as voids and delamination during 3D printing,which become the most vulnerable link of the composite.Understanding the relationship between voids and fracture behavior lays a foundation for defect suppression and performance improvement of subsequent printed parts.展开更多
目的分析2016—2022年云南省艾滋病自愿咨询检测(voluntary counselling and testing,VCT)和医疗机构医务人员主动提供人类免疫缺陷病毒(human immunodeficiency virus,HIV)检测咨询(provider initiated HIV testing and counselling,PI...目的分析2016—2022年云南省艾滋病自愿咨询检测(voluntary counselling and testing,VCT)和医疗机构医务人员主动提供人类免疫缺陷病毒(human immunodeficiency virus,HIV)检测咨询(provider initiated HIV testing and counselling,PITC)发现的HIV感染者和艾滋病患者(HIV感染者/艾滋病患者)特征的差异,为制定艾滋病检测策略提供依据。方法收集“中国疾病预防控制信息系统”中2016年1月1日—2022年12月31日通过VCT和PITC发现的新报告HIV感染者/艾滋病患者。利用非条件logistic回归分析比较不同途径发现的HIV感染者/艾滋病患者的特征、晚发现以及抗病毒治疗情况。结果2016—2022年云南省累计新报告VCT和PITC发现HIV感染者/艾滋病患者56378例,其中,VCT发现11750例(20.84%),PITC发现44628例(79.16%)。多因素logistic回归分析显示,女性(OR=0.84,95%CI:0.80~0.88)、配偶HIV阴性(OR=0.38,95%CI:0.35~0.41)及不清楚配偶HIV感染情况(OR=0.74,95%CI:0.61~0.89)者,通过PITC检测发现的可能性高。初中(OR=1.17,95%CI:1.11~1.24)、高中或中专(OR=1.31,95%CI:1.21~1.43)和大专及以上文化程度(OR=1.43,95%CI:1.30~1.57),通过男男同性性行为感染(OR=3.59,95%CI:3.29~3.92)、注射毒品感染(OR=1.63,95%CI:1.42~1.87)及配偶HIV阳性(OR=3.56,95%CI:3.38~3.75)者通过VCT门诊发现感染HIV的可能性高。与VCT相比,PITC中的其他就诊者检测(OR=1.41,95%CI:1.34~1.48)和术前/受血前检测(OR=1.20,95%CI:1.12~1.28)发现的HIV感染者/艾滋病患者晚发现的比例高,孕产期检测晚发现的比例低(OR=0.70,95%CI:0.60~0.81);与VCT相比,术前/受血(制品)前检测(OR=0.63,95%CI:0.57~0.70)、其他就诊者检测(OR=0.64,95%CI:0.59~0.69)发现的HIV感染者/艾滋病患者抗病毒治疗比例更低。结论VCT在早期发现病例、男男同性性行为筛查及抗病毒治疗促进方面有优势;PITC的推广有助于扩大普通人群的检测比例;可针对不同人群制定HIV感染者发现策略,促进早检测、早发现和早治疗。展开更多
基金supported by the National Key Research and Development Program Project of China(Grant No.2018YFB1106700).
文摘Polyether ether ketone(PEEK)-based continuous glass fiber reinforced thermoplastic composite offers advantages such as high strength,electrical insulation,and heat insulation.Parts manufactured using this composite and 3D printing have promising applications in aerospace,automobile,rail transit,etc.In this paper,a high-temperature melt impregnation method was used to successfully prepare the 3D printing prepreg filaments of the aforementioned composite.In the FDM 3D printing equipment,a nozzle of high thermal conductivity and wear-resistant copper alloy and a PEEK-based carbon fiber thermoplastic composite build plate with uniform temperature control were innovatively introduced to effectively improve the quality of 3D printing.The porosity of the 3D printed samples produced from the composite prepreg filament was analyzed under different printing parameters,and the mechanical properties and fracture mechanism of the printed parts were studied.The results show that the printing layer thickness,printing speed,printing temperature and build plate temperature have varying effects on the porosity of printed parts,which in turn affects tensile strength and the interlaminar shear strength(ILSS).When the printing layer thickness is 0.4 mm,printing speed is 2 mm/s,nozzle temperature is 430℃ and build plate temperature is 150℃,the tensile strength and ILSS of the composite printed parts reach their maximum values of 463.76 and 24.95 MPa,respectively.Microscopic analysis of the fracture morphology of the tensile specimens reveals that the 3D printed CGF/PEEK composite sample has three types of fracture mode,which are single filament bundle fracture,fracture mode of delamination,and fracture failure of the sample at the cross-section.The essence of the above three kinds of fracture mode is the difference of the interface bonding force of 3D printed CGF/PEEK composites.The fracture failure at the cross-section is that the continuous glass fibers in the composite are pulled out until they break,which is the main form of the failure of the composite under tensile load.The interfacial region of the composite is prone to microscopic defects such as voids and delamination during 3D printing,which become the most vulnerable link of the composite.Understanding the relationship between voids and fracture behavior lays a foundation for defect suppression and performance improvement of subsequent printed parts.
文摘目的分析2016—2022年云南省艾滋病自愿咨询检测(voluntary counselling and testing,VCT)和医疗机构医务人员主动提供人类免疫缺陷病毒(human immunodeficiency virus,HIV)检测咨询(provider initiated HIV testing and counselling,PITC)发现的HIV感染者和艾滋病患者(HIV感染者/艾滋病患者)特征的差异,为制定艾滋病检测策略提供依据。方法收集“中国疾病预防控制信息系统”中2016年1月1日—2022年12月31日通过VCT和PITC发现的新报告HIV感染者/艾滋病患者。利用非条件logistic回归分析比较不同途径发现的HIV感染者/艾滋病患者的特征、晚发现以及抗病毒治疗情况。结果2016—2022年云南省累计新报告VCT和PITC发现HIV感染者/艾滋病患者56378例,其中,VCT发现11750例(20.84%),PITC发现44628例(79.16%)。多因素logistic回归分析显示,女性(OR=0.84,95%CI:0.80~0.88)、配偶HIV阴性(OR=0.38,95%CI:0.35~0.41)及不清楚配偶HIV感染情况(OR=0.74,95%CI:0.61~0.89)者,通过PITC检测发现的可能性高。初中(OR=1.17,95%CI:1.11~1.24)、高中或中专(OR=1.31,95%CI:1.21~1.43)和大专及以上文化程度(OR=1.43,95%CI:1.30~1.57),通过男男同性性行为感染(OR=3.59,95%CI:3.29~3.92)、注射毒品感染(OR=1.63,95%CI:1.42~1.87)及配偶HIV阳性(OR=3.56,95%CI:3.38~3.75)者通过VCT门诊发现感染HIV的可能性高。与VCT相比,PITC中的其他就诊者检测(OR=1.41,95%CI:1.34~1.48)和术前/受血前检测(OR=1.20,95%CI:1.12~1.28)发现的HIV感染者/艾滋病患者晚发现的比例高,孕产期检测晚发现的比例低(OR=0.70,95%CI:0.60~0.81);与VCT相比,术前/受血(制品)前检测(OR=0.63,95%CI:0.57~0.70)、其他就诊者检测(OR=0.64,95%CI:0.59~0.69)发现的HIV感染者/艾滋病患者抗病毒治疗比例更低。结论VCT在早期发现病例、男男同性性行为筛查及抗病毒治疗促进方面有优势;PITC的推广有助于扩大普通人群的检测比例;可针对不同人群制定HIV感染者发现策略,促进早检测、早发现和早治疗。
