High-performance yttrium oxide-phenolic resin(Y_(2)O_(3)-PF)alternating coating was prepared on epoxy resin-based composite material using supersonic plasma spraying and dual-channel powder feeding technique.Y_(2)O_(3...High-performance yttrium oxide-phenolic resin(Y_(2)O_(3)-PF)alternating coating was prepared on epoxy resin-based composite material using supersonic plasma spraying and dual-channel powder feeding technique.Y_(2)O_(3)-coated PF(Y_(2)O_(3)/PF)powder was firstly sprayed onto the substrate,forming a transition layer,and then the spherical Y_(2)O_(3) powder and Y_(2)O_(3)/PF powder were alternately deposited to form the composite alternating coating.Results show that the alternating coating is mainly composed of deposited Y_(2)O_(3)/PF powder.The bonding strength between coating and substrate is as high as 26.48 MPa with the single-test maximum bonding strength of 28.10 MPa,and shear strength reaches 24.30 MPa.Additionally,the heat transfer effect caused by external Y_(2)O_(3) particles gradually softens and even melts PF,thus effectively avoiding the damage of high temperature to molecular structure and thereby promoting the crosslinking and curing effects of resin during the deposition process.In the meantime,the unmelted Y_(2)O_(3) powder results in the shot peening effect,which washes out and eliminates the powder particles with inferior deposition effect,ultimately improving the physical and chemical properties of the alternating coating.展开更多
目的:分析儿童体质测试成绩与粗大动作技能发展之间的关系,对不同儿童进行有针对性的指导和帮助。方法:北京市4所幼儿园共1 928名儿童,按照《国民体质测定标准手册》(幼儿部分)进行体质测试。随机整群选取了8个班作为整群对照(CG,n=244)...目的:分析儿童体质测试成绩与粗大动作技能发展之间的关系,对不同儿童进行有针对性的指导和帮助。方法:北京市4所幼儿园共1 928名儿童,按照《国民体质测定标准手册》(幼儿部分)进行体质测试。随机整群选取了8个班作为整群对照(CG,n=244),并根据体质测试成绩,选取成绩前10%的儿童(TG,n=203)和后10%儿童(BG,n=203),采用Test of Gross Motor Development-3(TGMD-3)对儿童粗大动作发展进行评估,对移动类和球类技能两大类基本动作的动作技能进行评估。结果:1)男童移动动作分值与女童无明显差别;2)男童球类动作技能好于女童,且随年龄增加其优势更加明显;3)体质测试成绩差的儿童,动作发展低于整体水平,特别是其球类动作技能的发展;4)随着年龄的增长,儿童动作发展的差距随年龄增长有逐渐扩大的趋势;5)粗大动作发展与体质测试结果中等相关。结论:针对3~6岁儿童,促进其体质发展,必须重视儿童动作技能的发展,对动作技能发展滞后的儿童应在教学活动中给予更多关注和指导。展开更多
基金National Natural Science Foundation of China(52130509,52275211,52075542)Supported by 145 Project+1 种基金Science and Technology New Star Project of Shaanxi Innovation Capability Support Program(2021KJXX-38)China Postdoctoral Science Foundation(2021M693883)。
文摘High-performance yttrium oxide-phenolic resin(Y_(2)O_(3)-PF)alternating coating was prepared on epoxy resin-based composite material using supersonic plasma spraying and dual-channel powder feeding technique.Y_(2)O_(3)-coated PF(Y_(2)O_(3)/PF)powder was firstly sprayed onto the substrate,forming a transition layer,and then the spherical Y_(2)O_(3) powder and Y_(2)O_(3)/PF powder were alternately deposited to form the composite alternating coating.Results show that the alternating coating is mainly composed of deposited Y_(2)O_(3)/PF powder.The bonding strength between coating and substrate is as high as 26.48 MPa with the single-test maximum bonding strength of 28.10 MPa,and shear strength reaches 24.30 MPa.Additionally,the heat transfer effect caused by external Y_(2)O_(3) particles gradually softens and even melts PF,thus effectively avoiding the damage of high temperature to molecular structure and thereby promoting the crosslinking and curing effects of resin during the deposition process.In the meantime,the unmelted Y_(2)O_(3) powder results in the shot peening effect,which washes out and eliminates the powder particles with inferior deposition effect,ultimately improving the physical and chemical properties of the alternating coating.
文摘目的:分析儿童体质测试成绩与粗大动作技能发展之间的关系,对不同儿童进行有针对性的指导和帮助。方法:北京市4所幼儿园共1 928名儿童,按照《国民体质测定标准手册》(幼儿部分)进行体质测试。随机整群选取了8个班作为整群对照(CG,n=244),并根据体质测试成绩,选取成绩前10%的儿童(TG,n=203)和后10%儿童(BG,n=203),采用Test of Gross Motor Development-3(TGMD-3)对儿童粗大动作发展进行评估,对移动类和球类技能两大类基本动作的动作技能进行评估。结果:1)男童移动动作分值与女童无明显差别;2)男童球类动作技能好于女童,且随年龄增加其优势更加明显;3)体质测试成绩差的儿童,动作发展低于整体水平,特别是其球类动作技能的发展;4)随着年龄的增长,儿童动作发展的差距随年龄增长有逐渐扩大的趋势;5)粗大动作发展与体质测试结果中等相关。结论:针对3~6岁儿童,促进其体质发展,必须重视儿童动作技能的发展,对动作技能发展滞后的儿童应在教学活动中给予更多关注和指导。
