针对医用乳腺X射线辐射源AGD测量数据处理过程中存在的难点问题,进行了试验研究,提出了2种有效的数据处理方法:近值法和线性拟合法。经过试验和比较得到以下结论:2种数据处理方法获得的测量结果及不确定度均符合相关技术规范要求,满足3 ...针对医用乳腺X射线辐射源AGD测量数据处理过程中存在的难点问题,进行了试验研究,提出了2种有效的数据处理方法:近值法和线性拟合法。经过试验和比较得到以下结论:2种数据处理方法获得的测量结果及不确定度均符合相关技术规范要求,满足3 U rel≤MPE的符合性判定准则。比较而言,线性拟合法获得的测量结果更加准确,其相对扩展不确定度(k=2)在5.7%~6.5%范围内,而近值法获得的相对扩展不确定度在6.4%~10%范围内。两种数据处理方法有效解决了医用乳腺X射线辐射源检定中不同模体厚度的转化因子和不同乳房成分修正因子如何确定的问题,为国家规程的下一步修订完善提供了参考,对其它同类测量数据的分析和处理也具有一定的借鉴作用。展开更多
A novel polyamide 6/silica nanocomposite containing epoxy resins(EPA6N) was prepared via in situ polymerization using tetraethoxysilane(TEOS) as the precursor of silica.The dynamic rheological properties of pure PA6 a...A novel polyamide 6/silica nanocomposite containing epoxy resins(EPA6N) was prepared via in situ polymerization using tetraethoxysilane(TEOS) as the precursor of silica.The dynamic rheological properties of pure PA6 and EPA6N at temperatures of 225 and 235 ℃ were investigated.The results of transmission electron microscopy(TEM) and atomic force microscopy(AFM) indicate that the silica particles are well dispersed in the polyamide 6 matrix on about 30 nm in diameter,which demonstrates that this method can effectively avoid agglomeration of the inorganic particles.The rheological results suggest that pure PA6 shows Newtonian behavior.However,the novel EPA6N exhibits a solid-like rheological behavior,which is due to the small size,large surface of silica particles and the stronger polyamide 6-silica chemical bond formed through the reactions of epoxy resins with end groups of PA6 molecular chains.The EPA6N also exhibits higher melt viscosity,storage modulus and loss modulus than those of pure PA6.展开更多
设计合成了4种不同结构类型的新型环境友好润滑油添加剂(LA1~LA4),采用1 H NMR和MALDI-TOF-MS确证了其分子结构。考察了4种添加剂的油溶性、热稳定性和抗腐蚀性;在四球摩擦机上考察了其在液体石蜡(LP)中的摩擦学性能;用扫描电子显微镜(S...设计合成了4种不同结构类型的新型环境友好润滑油添加剂(LA1~LA4),采用1 H NMR和MALDI-TOF-MS确证了其分子结构。考察了4种添加剂的油溶性、热稳定性和抗腐蚀性;在四球摩擦机上考察了其在液体石蜡(LP)中的摩擦学性能;用扫描电子显微镜(SEM)观察了钢球磨损的表面形貌,并用能谱分析仪(EDS)分析了钢球磨斑表面的元素组成,初步探讨了其摩擦作用机理。结果表明,4种添加剂具有优良的油溶性、热稳定性和抗腐蚀性,能够满足实际工况的要求;LP+1.0%LA2(质量分数,下同)的最大无卡咬负荷(PB)值比LP提高了87%,LP+1.0%LA3的烧结负荷(PD)值是LP的2倍,LP+1.0%LA3的钢球磨斑直径(WSD)只有LP的50%;SEM显示4种添加剂的加入能明显减小WSD,减少表面磨痕数量;EDS结果表明,添加剂在摩擦过程中形成复杂的反应膜。添加剂结构中的官能团会影响其性能,黄原酸酯基和羧酸酯基能够提高添加剂的极压抗磨性能。展开更多
文摘针对医用乳腺X射线辐射源AGD测量数据处理过程中存在的难点问题,进行了试验研究,提出了2种有效的数据处理方法:近值法和线性拟合法。经过试验和比较得到以下结论:2种数据处理方法获得的测量结果及不确定度均符合相关技术规范要求,满足3 U rel≤MPE的符合性判定准则。比较而言,线性拟合法获得的测量结果更加准确,其相对扩展不确定度(k=2)在5.7%~6.5%范围内,而近值法获得的相对扩展不确定度在6.4%~10%范围内。两种数据处理方法有效解决了医用乳腺X射线辐射源检定中不同模体厚度的转化因子和不同乳房成分修正因子如何确定的问题,为国家规程的下一步修订完善提供了参考,对其它同类测量数据的分析和处理也具有一定的借鉴作用。
基金Project(07A071) supported by the Scientific Research Foundation of Hunan Provincial Education Department
文摘A novel polyamide 6/silica nanocomposite containing epoxy resins(EPA6N) was prepared via in situ polymerization using tetraethoxysilane(TEOS) as the precursor of silica.The dynamic rheological properties of pure PA6 and EPA6N at temperatures of 225 and 235 ℃ were investigated.The results of transmission electron microscopy(TEM) and atomic force microscopy(AFM) indicate that the silica particles are well dispersed in the polyamide 6 matrix on about 30 nm in diameter,which demonstrates that this method can effectively avoid agglomeration of the inorganic particles.The rheological results suggest that pure PA6 shows Newtonian behavior.However,the novel EPA6N exhibits a solid-like rheological behavior,which is due to the small size,large surface of silica particles and the stronger polyamide 6-silica chemical bond formed through the reactions of epoxy resins with end groups of PA6 molecular chains.The EPA6N also exhibits higher melt viscosity,storage modulus and loss modulus than those of pure PA6.
文摘设计合成了4种不同结构类型的新型环境友好润滑油添加剂(LA1~LA4),采用1 H NMR和MALDI-TOF-MS确证了其分子结构。考察了4种添加剂的油溶性、热稳定性和抗腐蚀性;在四球摩擦机上考察了其在液体石蜡(LP)中的摩擦学性能;用扫描电子显微镜(SEM)观察了钢球磨损的表面形貌,并用能谱分析仪(EDS)分析了钢球磨斑表面的元素组成,初步探讨了其摩擦作用机理。结果表明,4种添加剂具有优良的油溶性、热稳定性和抗腐蚀性,能够满足实际工况的要求;LP+1.0%LA2(质量分数,下同)的最大无卡咬负荷(PB)值比LP提高了87%,LP+1.0%LA3的烧结负荷(PD)值是LP的2倍,LP+1.0%LA3的钢球磨斑直径(WSD)只有LP的50%;SEM显示4种添加剂的加入能明显减小WSD,减少表面磨痕数量;EDS结果表明,添加剂在摩擦过程中形成复杂的反应膜。添加剂结构中的官能团会影响其性能,黄原酸酯基和羧酸酯基能够提高添加剂的极压抗磨性能。
