含氮类金刚石薄膜的力学和摩擦学性能的研究

利用脉冲等离子体增强化学气相沉积系统沉积了含氮类金刚石碳薄膜.利用X射线光电子能谱和红外光谱分析了薄膜的化学键状态,在UMT摩擦磨损试验机上考察了薄膜的摩擦学性能,利用扫描电子显微镜分析了摩擦对偶球表面的转移膜形貌.结果表明:随着薄膜中氮含量的增加,薄膜中的sp2C含量增加,硬度有所降低,薄膜的平均摩擦系数先减小后增加.     

ZY型单摆仪

ＺＹ型单摆仪王舟远（云南工学院基础部６５００５１）单摆测重力加速度是物理实验中的基础实验，要求学生用多种摆长进行振动周期的测定．现有仪器和方法是通过移动摆球位置实现改变摆长，这不仅费时费力，也难做到随意选取摆长和摆长测量的准确．由于摆球位置变动，需移...     

Microwave absorption properties of a double-layer absorber based on nanocomposite BaFe12O19/α-Fe and nanocrystalline α-Fe microfibers

The nanocomposite BaFe12O19/α-Fe and nanocrystalline α-Fe microfibers with diameters of 1–5 μm, high aspect ratios and large specific areas are prepared by the citrate gel transformation and reduction process. The nanocomposite BaFe12O19/α-Fe microfibers show some exchange–coupling interactions largely arising from the magnetization hard(BaFe12O19) and soft(α-Fe) nanoparticles. For the microwave absorptions, the double-layer structures consisting of the nanocomposite BaFe12O19/α-Fe and α-Fe microfibers each exhibit a wide band and strong absorption behavior. When the nanocomposite BaFe12O19/α-Fe microfibers are used as a matching layer of 2.3 mm in thickness and α-Fe microfibers as an absorbing layer of 1.2 mm in thickness, the optimal reflection loss(RL) achieves-47 dB at 15.6 GHz, the absorption bandwidth is about 12.7 GHz ranging from 5.3 to 18 GHz, exceeding-20 dB, which covers 72.5% C-band(4.2–8.2 GHz)and whole X-band(8.2–12.4 GHz) and Ku-band(12.4–18 GHz). The enhanced absorption properties of these double-layer absorbers are mainly ascribed to the improvement in impedance matching ability and microwave multi-reflection largely resulting from the dipolar polarization, interfacial polarization, exchange–coupling interaction, and small size effect.     

我国某城市市售食品中PCDD/Fs污染水平和人群二(噁)英膳食暴露量研究

近年来,国际上相继发生了多次二(噁)英污染食物和饲料的意外事件,引起各国政府的高度重视和公众的持续关注.(噁)2006年1月比利时又发生了猪肉、禽肉产品中致癌物质二(噁)英超标事件,导致许多国家停止进口比利时等国的猪肉和禽肉产品及动物源性饲料.     

汽车尾气净化器用活性氧化铝的研制

应用一种新的氧化铝制备方法-水合含碳氧化铝热解法, 通过引入模板导向剂和热稳定助剂, 制得了Al2O3纯度≥99.9%, 一次晶粒0.1 μm, 平均粒径0.2～3 μm, BET比表面积148.4 m2*g-1(900 ℃, 1 h焙烧)的活性氧化铝. 该方法所得产品性能稳定, 孔容大, 孔径分布合理, 纯度高. 样品经用户小批量试用认定 其新鲜态、老化后的比表面积和小杂质含量(P, S, Cl, Pb)指标均优于国内同类产品, Al2O3涂层粘结强度、涂层负载量等性能达到国际先进水平.     

A Search for Solar Axions and Anomalous Neutrino Magnetic Moment with the Complete Panda X-Ⅱ Data

We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^-12 for an axion mass less than 0.1 keV/c² and the neutrino magnetic moment μv<4.9×10^-11μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.     

几种4-取代-L-脯氨酸衍生物的合成

以Boc-(4R)-羟基-(2S)-脯氨酸为原料,在NaH作用下与苄位溴代试剂发生醚化反应,合成了几种4-取代-L-脯氨酸类手性催化剂,即在(4R)-羟基-(2S)-脯氨酸的4-位上引入不同的苄氧基以期提高其催化活性和脂溶性,并通过1 H NMR、13 C NMR和HRMS对合成产物的结构进行表征,确定其为目标产物.实验结果还表明,当苯环上连有强的吸电子基团时反应很难进行,而当连有给电子基团时反应相对较容易进行且反应条件较温和.