云南烤烟特征化学成分分析

采用偏最小二乘法对云南省内159个与省外30个种植点生产的烤烟烟叶中102种主要化学成分和致香成分进行了比较分析。结果表明云南省内生产的烤烟烟叶与省外生产的烤烟烟叶能够得到良好地区分,进一步数据分析显示云南烤烟的特征化学成分为草酸、十四酸、棕榈酸、十八酸、油酸、亚油酸、亚麻酸、新绿原酸、芸香苷、山奈酚苷、3-甲基-2-丁烯醛、糠醇、2-乙酰吡啶、巨豆三烯酮。     

不同烟草种质腺毛密度鉴定分析

为筛选高腺毛密度种质资源供烟草育种利用,加快香气性状遗传改良步伐,本研究共观察了110份材料的长短柄腺毛,并统计其密度。结果表明,各品种长短柄腺毛的长短、腺头大小、密度均不一致;短柄腺毛、长柄腺毛和总腺毛密度的变异系数分别为25.4%、29.3%和23.4%,试验材料存在广泛变异;短柄腺毛密度、长柄腺毛密度和总腺毛密度比对照MSK326多的材料数分别为34份、17份和19份,其中共有的材料数为11份;总体上,叶片上表面的短柄腺毛密度大于下表面,叶片下表面的长柄腺毛密度大于上表面,上下表面的总腺毛密度差异没有一致规律,叶片长柄腺毛密度要大于短柄腺毛,但存在个别特异材料与该规律相反,这些材料基本为地方种质;聚类分析结果显示,在阈值为4时,可以将110份材料分为5类,除特殊的B类外,其他几类的腺毛密度大小为A > C > E > D;云烟116、V2、红花大金元、席娄烟等可以作为高腺毛密度材料,为育种利用提供参考。     

多光谱数据融合技术对绒柄牛肝菌产地的鉴别

采集5?个产地96?份绒柄牛肝菌样品的红外光谱和紫外光谱,结合多光谱信息融合策略,建立快速、有效鉴别绒柄牛肝菌产地的方法。运用多元散射校正、标准正态变量、二阶导数等预处理方法对原始光谱数据进行优化处理,减少噪音干扰。选取具有指纹特性的光谱信息进行初级数据融合;通过偏最小二乘判别分析（partial least squares-discriminant analysis,PLS-DA）筛选光谱数据中变量在投影方向重要程度大于1的波段,进行中级数据融合。利用优化处理后的单一光谱数据及多光谱融合数据建立PLS-DA模型和支持向量机（support vector machine,SVM）判别模型,比较两种判别模型对绒柄牛肝菌产地的鉴别效果。结果显示,通过红外光谱、紫外光谱、初级融合和中级融合数据分别建立PLS-DA模型,对绒柄牛肝菌产地的预测正确率为56.25%、56.25%、62.50%和81.25%;建立SVM判别模型,产地预测正确率分别为90.63%、65.63%、87.50%和96.88%,表明中级融合技术对绒柄牛肝菌产地鉴别效果显著,优于其他技术;并且SVM判别模型对牛肝菌产地区分效果优于PLS-DA模型。采用中级融合技术建立SVM判别模型,能够快速、有效鉴别不同产地绒柄牛肝菌,同时为食品质量监控提供有效方法和理论基础。     

加热非燃烧烟草薄片的热解特征研究

采用热重技术结合标准均方根误差,研究8种烟草薄片、3种非烟草纤维以及烟草自身纤维的热解特性及差异度。结果表明:传统卷烟用薄片的热重曲线与加热非燃烧烟草薄片的热重曲线存在很大的差异,热解差异度为37.97%。主要表现在加热非燃烧烟草薄片的热重曲线上增加了1个保润剂的峰,且水分、提取液和木质素的含量相对较高,而半纤维素、纤维素和残留物的质量明显较低。     

天然维生素E的提取工艺与检测技术

简要介绍了维生素E的分布和生理作用,重点综述了天然维生素E提取工艺及维生素E的检测技术。     

Piezoelectric formation mechanisms and phase transformation of poly(vinylidene fluoride)/graphite nanosheets nanocomposites

The β-phase of poly(vinylidene fluoride) (PVDF) is of great technical importance because of its high dielectric constant and piezoelectric effect. In this work, we exfoliated and dispersed natural graphite to prepare 2D-graphite nanosheets (GNS) and prepared PVDF/GNS nanocomposites with different GNS volumes from 1 to 7 ml as film via solution casting method. The concentration of the supernatant was about 0.3 mg/mL. The effect of GNS on the β-phase formation and mechanisms of piezoelectric formation in the PVDF/GNS nanocomposites were investigated. The results showed that with the varying amounts of GNS, the crystalline structure, the morphology, and the dielectric and piezoelectric properties of PVDF/GNS nanocomposites changed. GNS acts as an effective nucleation agent with the orientation almost parallel to the surface of the film meanwhile increasing the amount of beta phase in the PVDF matrix with increasing amount of GNS, also the relative dielectric constant and dielectric loss of the nanocomposites increased with increasing amount of GNS. The value d₃₃ also increased with increasing amount of GNS, and reached a maximum (6.7 pC/N) with 6 ml GNS. The mechanism of piezoelectric formation was proposed based on experiment results of PVDF/GNS nanocomposites.     

Deep knowledge tracking algorithm based on forgetting law

Knowledge tracking(KT) algorithm, which can model the cognitive level of learners, is a fundamental artificial intelligence approach to solve the personalized learning problem in the field of education. The recently presented separated self-attentive neural knowledge tracing(SAINT) algorithm has got a great improvement on predictingthe accuracy of students’ answers in comparison with the present other methods.However there is still potential to enhance its performance for it fails to effectively...