A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R...A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. <展开更多
A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R...A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. 【展开更多
Ar/CH3OH and Ar/N2/CH3OH plasma jets were generated at atmospheric pressure by dual-frequency excitations. Two different cases were studied with focus laid on the generation of CN radicals. In one case Ar gas passed t...Ar/CH3OH and Ar/N2/CH3OH plasma jets were generated at atmospheric pressure by dual-frequency excitations. Two different cases were studied with focus laid on the generation of CN radicals. In one case Ar gas passed through a bubbler with saturated methanol steam but without addition of N2 （Ar/CH3OH plasma）. In the other case N2 passed through the bubbler with saturated methanol steam （Ar/N2/CH3OH plasma）. The optical emission lines of CN radicals have been observed in these two cases of plasma discharges. The addition of N2 can significantly increase the optical emission intensity of CN bands.展开更多
为实现光谱技术对麦麸固体发酵过程中不同成分变化的在线监测,通过国家标准方法测定61份麦麸固体发酵饲料样本的蛋白质、水分、总酚和粗纤维含量,采集样本近红外光谱(NIR)和傅里叶变换红外光谱(FT-IR),经过标准正态变换(standard normal...为实现光谱技术对麦麸固体发酵过程中不同成分变化的在线监测,通过国家标准方法测定61份麦麸固体发酵饲料样本的蛋白质、水分、总酚和粗纤维含量,采集样本近红外光谱(NIR)和傅里叶变换红外光谱(FT-IR),经过标准正态变换(standard normal variate transformation,SNV)、多元散射校正(multiplicative scatter correction,MSC)、平滑(smoothing)等9种预处理方法对原始光谱进行校正,结合偏最小二乘法(partial least squares,PLS)建立4种成分的NIR和FT-IR定量分析模型并进行比较分析。结果表明:所建立的4种成分NIR和FT-IR模型的训练集决定系数(Rc^(2))和验证集决定系数(Rp^(2))均大于0.8,交叉验证均方根误差(root mean square error of cross validation,RMSECV)小于2.0,训练集均方根误差(root mean square error of calibration,RMSEC)和验证集均方根误差(root mean square error of prediction,RMSEP)小于1.0。因此,所建立的NIR和FT-IR定量分析模型具有较好的准确性和稳定性,能够对麦麸固体发酵过程中不同成分变化实行快速监测。展开更多
采用核磁共振方法检测肝硬化、肝细胞癌(简称肝癌)患者和健康人血清中代谢物,研究3组血清代谢物组的差异。利用偏最小二乘法-判别式分析(partial least square-discriminant analysis,PLS-DA)对NMR谱数据进行模式识别分析,探讨利用基于1...采用核磁共振方法检测肝硬化、肝细胞癌(简称肝癌)患者和健康人血清中代谢物,研究3组血清代谢物组的差异。利用偏最小二乘法-判别式分析(partial least square-discriminant analysis,PLS-DA)对NMR谱数据进行模式识别分析,探讨利用基于1HNMR代谢组学技术诊断肝癌的可行性。结果表明,与健康人相比,肝硬化、肝癌患者血清中脂质(低密度脂蛋白和极低密度脂蛋白)、胆碱、乙酰乙酸等含量减少,谷氨酰胺、丙酮酸、苯丙氨酸、酪氨酸等含量增加。PLS-DA分析结果显示肝癌患者可与健康人、肝硬化患者鉴别开来,肝癌诊断灵敏度达92.1%,假阳性率为5.7%,优于血清甲胎蛋白(alpha-fetoprotein,AFP)检测。研究结果表明,基于1HNMR代谢组学技术结合PLS-DA的方法具有灵敏、准确、重复性好等优点,有助于肝癌早期诊断。展开更多
文摘A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. <
文摘A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. 【
基金supported by National Natural Science Foundation of China(No.11165012)China Postdoctoral Science Foundation Funded Project(Nos.2011M501494,2012T50831)+1 种基金Project of Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province,ChinaProject of Northwest Normal University of China(NWNU-LKQN-11-9)
文摘Ar/CH3OH and Ar/N2/CH3OH plasma jets were generated at atmospheric pressure by dual-frequency excitations. Two different cases were studied with focus laid on the generation of CN radicals. In one case Ar gas passed through a bubbler with saturated methanol steam but without addition of N2 （Ar/CH3OH plasma）. In the other case N2 passed through the bubbler with saturated methanol steam （Ar/N2/CH3OH plasma）. The optical emission lines of CN radicals have been observed in these two cases of plasma discharges. The addition of N2 can significantly increase the optical emission intensity of CN bands.
文摘为实现光谱技术对麦麸固体发酵过程中不同成分变化的在线监测,通过国家标准方法测定61份麦麸固体发酵饲料样本的蛋白质、水分、总酚和粗纤维含量,采集样本近红外光谱(NIR)和傅里叶变换红外光谱(FT-IR),经过标准正态变换(standard normal variate transformation,SNV)、多元散射校正(multiplicative scatter correction,MSC)、平滑(smoothing)等9种预处理方法对原始光谱进行校正,结合偏最小二乘法(partial least squares,PLS)建立4种成分的NIR和FT-IR定量分析模型并进行比较分析。结果表明:所建立的4种成分NIR和FT-IR模型的训练集决定系数(Rc^(2))和验证集决定系数(Rp^(2))均大于0.8,交叉验证均方根误差(root mean square error of cross validation,RMSECV)小于2.0,训练集均方根误差(root mean square error of calibration,RMSEC)和验证集均方根误差(root mean square error of prediction,RMSEP)小于1.0。因此,所建立的NIR和FT-IR定量分析模型具有较好的准确性和稳定性,能够对麦麸固体发酵过程中不同成分变化实行快速监测。
文摘采用核磁共振方法检测肝硬化、肝细胞癌(简称肝癌)患者和健康人血清中代谢物,研究3组血清代谢物组的差异。利用偏最小二乘法-判别式分析(partial least square-discriminant analysis,PLS-DA)对NMR谱数据进行模式识别分析,探讨利用基于1HNMR代谢组学技术诊断肝癌的可行性。结果表明,与健康人相比,肝硬化、肝癌患者血清中脂质(低密度脂蛋白和极低密度脂蛋白)、胆碱、乙酰乙酸等含量减少,谷氨酰胺、丙酮酸、苯丙氨酸、酪氨酸等含量增加。PLS-DA分析结果显示肝癌患者可与健康人、肝硬化患者鉴别开来,肝癌诊断灵敏度达92.1%,假阳性率为5.7%,优于血清甲胎蛋白(alpha-fetoprotein,AFP)检测。研究结果表明,基于1HNMR代谢组学技术结合PLS-DA的方法具有灵敏、准确、重复性好等优点,有助于肝癌早期诊断。
