为了深入理解纳米Al-Ni合金低温下的电子输运过程, 使用自主研发的电磁感应加热-自悬浮定向流法制备出Al, Ni和Al-Ni纳米合金粉末, 并采用真空热压设备将纳米粉末压制成纳米晶块体, 利用自主搭建的低温热电测量系统研究了Al-Ni纳米合金的电阻率随温度(8~300 K)的变化规律。研究结果表明: Al-Ni纳米合金由于形成有序晶相而仍然与Al, Ni纳米晶一样, 电阻率随温度的降低而降低。纳米Ni3Al-Ni和NiAl-Ni在居里温度点附近出现了电阻率随温度变化的极大值点, 因为单质Ni的影响, Ni3Al-Ni的居里温度比粗晶Ni3Al提高了20 K。由于磁子-电子散射作用和声子-电子散射作用, 纳米Ni3Al-Ni, NiAl-Ni和Ni的电阻率在低温下(8~40 K)与温度呈T2和T4关系。

The growth characteristics of Aspergillus parasiticus incubated on two culture media were examined using shortwave infrared (SWIR, 1000–2500 nm) hyperspectral imaging (HSI) in this work. HSI images of the A. parasiticus colonies growing on rose bengal medium (RBM) and maize agar medium (MAM) were recorded daily for 6 days. The growth phases of A. parasiticus were indicated through the pixel number and average spectra of colonies. On score plot of the first principal component (PC1 T and PC2, four growth zones with varying mycelium densities were identified. Eight characteristic wavelengths (1095, 1145, 1195, 1279, 1442, 1655, 1834 and 1929 nm) were selected from PC1 loading, average spectra of each colony as well as each growth zone. Furthermore, support vector machine (SVM) classifier based on the eight wavelengths was built, and the classification accuracies for the four zones (from outer to inner zones) on the colonies on RBM were 99.77%, 99.35%, 99.75% and 99.60% and 99.77%, 99.39%, 99.31% and 98.22% for colonies on MAM. In addition, a new score plot of PC2 and PC3 was used to differentiate the colonies incubated on RBM and MAM for 6 days. Then characteristic wavelengths of 1067, 1195, 1279, 1369, 1459, 1694, 1834 and 1929 nm were selected from the loading of PC2 and PC3. Based on them, a new SVM model was developed to differentiate colonies on RBM and MAM with accuracy of 100.00% and 99.99%, respectively. In conclusion, SWIR hyperspectral image is a powerful tool for evaluation of growth characteristics of A. parasiticus incubated in different culture media.