可见/近红外光谱的油茶籽油三元体系掺假检测模型优化

采用可见/近红外光谱技术结合化学计量学方法对油茶籽油三元体系掺假进行定量检测研究。将菜籽油和花生油按不同比例掺入纯油茶籽油中,获得掺假样本。采集纯油茶籽油及掺假样本在350~1 800 nm范围内的可见/近红外光谱数据,随机分为校正集和预测集,并从不同建模波段、预处理方法及建模方法角度对掺假预测模型进行优化。研究结果表明,菜籽油、花生油和总掺伪量的最优建模波段及预处理方法分别为750~1 770,900~1 770 ,870~1 770 nm和多元散射校正(MSC)、标准归一化处理(SNV)和二阶微分,而最优的建模方法均为最小二乘支持向量机(LSSVM)。对于最优掺假模型,菜籽油、花生油和总掺伪量的预测集相关系数(R_p)和预测均方根误差(RMSEP)分别为0.963,0.982,0.993和2.1%,1.5%,1.8%。由此可见,可见/近红外光谱技术结合化学计量学方法可以用于油茶籽油的三元体系掺假定量检测。     

A Note on Casoratian Solutions to Two-Dimensional Toda Lattice

In this short paper we generalize the conditions that Casoratian entries satisfy for the two-dlmenslonal Toda lattice. Although we finally conclude that our generalization is trivial in some sense for getting new solutions, our discussion is still helpful for the study of Wronskian technique.     

Near-Field Fluorescence and Topography Characterization of a Single Nanometre Fluorophore by Apertureless Tip-Enhanced Scanning Near-Field Microscopy

Tip-enhanced near-field fluorescence and topography characterization of a single nanometre fluorophore is conducted by using an apertureless scanning near-field microscopy system. A fluorophore with size 80hm is mapped with a spatial resolution of 10hm. The corresponding near-field fluorescence data shows significant signal enhancement due to the apertureless tip-enhanced effect. With the nanometre spatial resolution capability and nanometre local tip-enhanced effect, the apertureless tip-enhanced scanning near-field microscopy may be further used to characterize a single molecule by realizing the local near-field spectrum assignment corresponding to topography at nanometre scale.     

Effect of Laser Cooling on Frequency Standard of Single Ca^＋ Ion Trapped in a Radio-Frequency Paul Trap

The source of systematic frequency shift of single-ion optical frequency standard of^40 Ca^＋ ion trapped in endcap trap and laser-cooled to a few of mK is analysed and calculated. Second-order Doppler shift, Stark shift due to micromotion and thermal motion, blackbody Stark shift and ac Stark shift are calculated for the ground state and excited 3d ^2D5/2 state. The Hertz-level measurement of the optical clock frequency in a single ^40Ca^＋ ion can be performed.     

Total Dose Radiation Tolerance of Phase Change Memory Cell with GeSbTe Alloy

Phase change memory （PCM） cell array is fabricated by a standard complementary metal-oxide-semiconductor process and the subsequent special fabrication technique. A chalcogenide Ge2Sb2Te5 film in thickness 50hm deposited by rf magnetron sputtering is used as storage medium for the PCM cell. Large snap-back effect is observed in current-voltage characteristics, indicating the phase transition from an amorphous state （higher resistance state） to the crystalline state （lower resistance state）. The resistance of amorphous state is two orders of magnitude larger than that of the crystalline state from the resistance measurement, and the threshold current needed for phase transition of our fabricated PCM cell array is very low （only several μA）. An x-ray total dose radiation test is carried out on the PCM cell array and the results show that this kind of PCM cell has excellent total dose radiation tolerance with total dose up to 2 ×10^6 rad（Si）, which makes it attractive for space-based applications.     

快脉冲直线变压器驱动源模块的原理及实验

 介绍了直线型变压器驱动源（LTD）产生快脉冲的基本原理及技术优势,阐述了快脉冲LTD模块设计的要点,设计了输出脉冲上升时间小于100 ns的快脉冲LTD模块,并进行了初步的实验研究。实验得到该LTD模块充电±16 kV时,短路放电的电流峰值为23.7 kA,电流振荡1/4周期为69.6 ns;充电±50 kV驱动0.85 Ω负载时,电流峰值为41.4 kA,上升时间为36.8 ns（10%~90%）和60.8 ns（0~100%）。     

用于同步辐射光源的成像板粉末衍射系统

报道了我们研制的一套成像板粉末衍射装置,对其误差来源进行了详细的分析讨论,并与衍射仪进行了比较.该装置的半径为143.3mm,最大测量角度范围不160°，最大角度(2q )偏差小于0.03°,这些性能指标已被实验所证实,完全可应用于粉末衍射全谱的测量.     

荧光法研究对-二甲氨甲基-杯[8]芳烃与二苯胺磺酸钠包结作用

用荧光法研究了水溶性对-二甲氨甲基-杯[8]芳烃与二苯胺磺酸钠的相互作用。发现当对-二甲氨甲基-杯[8]芳烃加入到二苯胺磺酸钠溶液时,二苯胺磺酸钠的荧光峰发生了明显的蓝移,荧光增强,可能的作用机理是二苯胺磺酸钠中的磺酸根与对-二甲氨甲基-杯[8]芳烃中带正电的氮原子之间有较强的静电作用,二苯胺磺酸钠进入了对-二甲氨甲基-杯[8]芳烃的疏水空腔。同时研究了几种有机溶剂对包结物的荧光强度的影响,初步探讨了其作用机理。     

CO+分子离子彗尾带系在近红外区域的光谱研究

CO 分子离子是一种重要的瞬态自由基分子,许多研究者对该带系进行了大量的研究。文章采用光外差-磁旋转-速度调制光谱技术测量了12C16O 分子离子彗尾带系(A2Πi-X2Σ )在近红外区域的3个支带(0,3),(1,4)和(3,6)的振转吸收光谱。利用最小二乘法拟合,得到了上态A2Πi(ν′=0,1,3)的精确的分子常数。进一步验证了光外差-磁旋转-速度调制光谱技术在吸收光谱测量中的优越性。     

Dynamic Scaling of Ramified Clusters Formed on Liquid Surfaces

A comprehensive simulation model -deposition,diffusion, rotation, reaction and aggregation model is presented to simulate the formation processes of ramified clusters on liquid surfaces, where clusters can diffuse and rotate easily. The mobility (including diffusion and rotation) of clusters is related to its mass, which is given by Dm = Dos-γD and θm =′θos-γθ, respectively. The influence of the reaction probability on the kinetics and structure formation is included in the simulation model. We concentrate on revealing dynamic scaling during ramified cluster formation. For this purpose, the time evolution of the cluster density and the weight-average cluster size as well as the cluster-size distribution scaling function at different time are determined for various conditions. The dependence of the cluster density on the deposition flux and time-dependence of fractal dimension are also investigated. The obtained results are helpful in understanding the formation of clusters or thin film growth on liquid surfaces.