Standardization of milk infrared spectra for the retroactive application of calibration models

The objective of this study was to standardize the infrared spectra obtained over time and across 2 milk laboratories of Canada to create a uniform historical database and allow (1) the retroactive application of calibration models for prediction of fine milk composition; and (2) the direct use of spectral information for the development of indicators of animal health and efficiency. Spectral variation across laboratories and over time was inspected by principal components analysis (PCA). Shifts in the PCA scores were detected over time, leading to the definition of different subsets of spectra having homogeneous infrared signal. To evaluate the possibility of using common equations on spectra collected by the 2 instruments and over time, we developed a standardization (STD) method. For each subset of data having homogeneous infrared signal, a total of 99 spectra corresponding to the percentiles of the distribution of the absorbance at each wavenumber were created and used to build the STD matrices. Equations predicting contents of saturated fatty acids, short-chain fatty acids, and C18:0 were created and applied on different subsets of spectra, before and after STD. After STD, bias and root mean squared error of prediction decreased by 66% and 32%, respectively. When calibration equations were applied to the historical nonstandardized database of spectra, shifts in the predictions could be observed over time for all investigated traits. Shifts in the distribution of the predictions over time corresponded to the shifts identified by the inspection of the PCA scores. After STD, shifts in the predicted fatty acid contents were greatly reduced. Standardization reduced spectral variability between instruments and over time, allowing the merging of milk spectra data from different instruments into a common database, the retroactive use of calibrations equations, or the direct use of the spectral data without restrictions.     

表面修饰LaF3：Tb3＋纳米粒子的合成及敏化发光研究

以油酸（OA）作为表面修饰剂,在乙醇一水体系中合成了油酸修饰的LaF3：Tb3＋纳米粒子（OA—LaF3：Tb3＋）,用红外光谱（IR）、X-射线衍射分析（XRD）、透射电镜（TEM）、紫外光谱（UV）、荧光光谱（FS）对所合成的纳米粒子进行了表征和荧光性能研究,结果表明,OA与纳米粒子发生了化学键合作用;所制备的纳米粒子在三氯甲烷中的溶解性很好;纳米粒子大小均匀,粒径约为10nm;纳米粒子的晶相为LaF,的六方体结构;在312nm紫外光激发下,纳米粒子发射Tbn的特征荧光,表明表面修饰剂OA对Tbn具有较好的敏化作用。     

地震动加加速度反应谱的概念及特性研究

加加速度是加速度关于时间的变化率,反映了结构受力变化情况。地震动加加速度及其反应谱的研究可以加强人们对地震动非平稳性的认识。阐述了加加速度的力学意义及研究价值,探讨了计算加加速度的动力学方法并对其优缺点进行了比较。建立了地震动下弹性及弹塑性加加速度反应谱的求解方法。根据场地类型、放大系数、延性系数及折减系数等影响因素对加加速度反应谱的特性进行了研究,并提出了冲击折减系数的概念。结果表明加加速度对中短周期的建筑结构作用较明显,适当提高延性将有效降低加加速度造成的冲击效应。冲击折减系数随着结构周期增大明显增大,加加速度对于长周期结构的影响一般可以忽略。     

New Molecular Complex of Fullerene C60 with Porphyrin Dimer [FeTPP]2O: Synthesis and Crystal Structure

Abstract

New molecular complex of C₆₀ with covalently linked (Fe^IIITPP)₂O · C₆₀ dimer has been obtained. The complex has isolated packing of fullerenes in which fullerene molecule is embraced in a pocket built by porphyrins. (Fe^IIITPP)₂O preserves its initial geometry in the complex. The Fe···C(C₆₀) contacts are in the 3.239–3.513 Å range indicating the absence of Fe–C₆₀ coordination. This results in the similarity of the EPR spectra of the complex and parent (Fe^IIITPP)₂O.     

设计谱长周期段取值与能量特征研究

基于由随机振动理论得到的功率谱密度与加速度反应谱之间的关系,以及由傅里叶幅值谱精确计算输入能量反应谱方法,提出了建立与设计加速度反应谱匹配的输入能量谱方法。计算了与《建筑抗震设计规范》(GB50011-2010)设计反应谱匹配的输入能量谱,通过与实际强震记录输入能量谱特征对比,对设计反应谱长周期段输入能量特征进行了分析。结果表明,由于规范设计谱长周期段取值比较保守,在长周期段输入能量随着周期变长逐渐增加,与实际地震动记录输入能量谱长周期特征明显不同。根据实际强震记录输入能量谱特征,给出了设计反应谱长周期直线下降段的取值建议。     

矩形波冲击下瓦楞纸板缓冲包装衬垫的冲击响应

以已有的瓦楞纸板本构模型为基础,建立动力学方程,通过数值计算方法,着重研究了瓦楞纸板在矩形波激励下阻尼系数及线性参量对瓦楞纸板缓冲包装系统冲击谱和破损边界的影响.     

基于表面反射率的赤潮卫星荧光线高度算法比较

采用现场实测和室内培养两种方式测定了甲藻、赤潮异弯藻和叉角藻等赤潮藻以及新月菱形藻、海洋蓝绿藻、叉鞭金藻、塔胞藻、扁藻和小球藻等非赤潮藻类光谱曲线。采用的各卫星(MERIS,GLI,MODIS)的荧光波段数据按照其中心波长,从实际测定的高光谱反射率曲线提取而来,并按照荧光高度的计算公式得到其荧光高度。同时,采用统计分析方法建立荧光高度与叶绿素浓度的关系。10种藻类水体的荧光线高度与叶绿素α的回归分析结果显示了良好的线性关系,但部分藻种出现了负相关的结果。因为在高叶绿素浓度即赤潮条件下,浮游植物在荧光波段(685nm附近)和近红外波段(700～750nm)复杂的光谱行为,使得采用星载遥感器的叶绿素荧光波段探测某些藻类的赤潮时会出现偏差。同时,由于不同藻类的荧光高度与叶绿素浓度的关系也不一致,本文建议针对单独的赤潮种类应建立特定的荧光算法。相关问题还需要在实测的基础上进行更深入的研究。     

稀土配合物Eu(TTA)3Phen掺杂的PMMA树脂的制备及其发光性能研究

用新的合成方法合成了稀土配合物Eu(TTA) 3Phen。研究了该配合物的IR、UV、TGA、元素分析和荧光光谱。该配合物具有良好的发光性能和热稳定性。采用加热方法将Eu(TTA) 3Phen掺入PMMA树脂中 ,制成发光塑料树脂 ,并测定其发光性能。结果表明 ,Eu(TTA) 3Phen掺入PMMA树脂后仍保持该稀土配合物原有的发光特性 ,制成的Eu(TTA) 3Phen -PMMA树脂复合材料具有良好的发光性能 ,其发光强度与Eu(TTA) 3Phen掺入的含量有关。